Jean-luc Polleux - Academia.edu (original) (raw)

Papers by Jean-luc Polleux

2021 International Topical Meeting on Microwave Photonics (MWP), 2021

Radio over Fiber systems based on 850nm Vertical Cavity Surface Emitting Lasers constitute an att... more Radio over Fiber systems based on 850nm Vertical Cavity Surface Emitting Lasers constitute an attractive solution to realize cost-and-consumption-efficient 4G/5G Front Hauls while reusing the existing in-building G.652 fiber infrastructures. In view of such application, the mitigation of the nonlinearities of these systems through an effective local predistortion loop is demonstrated for a transmission distance of 2Km.

Journal of Lightwave Technology, 2021

This paper describes a compact and low cost optically fed antenna for using as a receiver in 5G c... more This paper describes a compact and low cost optically fed antenna for using as a receiver in 5G cellular networks and in distributed antenna systems. It compares the performance of two different topologies of patch antennas tightly integrated with vertical-cavity surface-emitting lasers (VCSELs), without the need for an amplifier stage or matching circuit. Opto-microwave (OM) gain of −21.5 dB at 5.15 GHz for the Microstrip patch antenna (MPA), and −24.2 dB at 4.8 GHz for the Grounded Coplanar patch antenna (GCPA) are achieved. The MPA architecture is quite original as it removes the need for RF feed lines through a direct injection of the signal from the patch to the VCSEL. The paper evaluates the different contributions to the total gain due to the VCSEL responsivity, the coupling between the optical fiber and the VCSEL, the wire-bonding losses and the antenna gain, with the goal of optimizing the steps at which major losses occur.

Journal of Lightwave Technology, 2021

The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, sho... more The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, showing how, particularly within In-Building scenarios, it allows to combine the pervasiveness of the first technique with the beam-steering capability of the second. A cost-effective 3-element RoF-TMA system is presented and investigated, to realize a solution for small offices / private houses (SoHos). It is confirmed that bringing the feed to the antennas through the RoF system keeps the possibility for the TMA to radiate power at different frequencies, in each case with a steerable maximum direction. Referring to mobile signals with RF carriers of few GHz, it is shown that to guarantee, for each of the multiple beams emitted by the TMA, a maximum deviation of 5 from its ideal direction, it is sufficient that among the output branches of the 1:3 optical splitter utilized the length difference is maintained in the range of a few millimeters.

2018 International Topical Meeting on Microwave Photonics (MWP), 2018

This paper presents for the first time the transmission of LTE signal based-on Radio-over-Fiber (... more This paper presents for the first time the transmission of LTE signal based-on Radio-over-Fiber (RoF) scheme by using SiGe Hetero-junction Photo-Transistor as photo-receiver. The photo-transistor is fabricated based-on the commercial bipolar transistor technology. An 850 nm single mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fiber (SSMF) are used to complete the link so that makes the total cost of the system very low. The transmission of 20 MHz bandwidth LTE signal with high modulation format is achieved. The performance of the system is evaluated through the measurement of Error Vector Magnitude (EVM) under different operation conditions of the photo-transistor (in photodiode mode, photo-transistor mode and two terminals mode). We reach an EVM below 8% for the input power of -25 dBm to -2 dBm when the photo-transistor operates under two terminals condition. This EVM value fulfills the requirements of the LTE standard for 64-QAM modulation. The stability of the system with regard temperature variation and modal noise is also presented.

2020 Italian Conference on Optics and Photonics (ICOP), 2020

Commercial couplers designed for 1550nm are conveniently adopted for realizing efficient Radio-ov... more Commercial couplers designed for 1550nm are conveniently adopted for realizing efficient Radio-over-Fiber links operating at 850nm on the standard G.652 single mode fiber. In particular, exploiting the mode filtering properties observed in these couplers when excited at 850nm, a multi-wavelength system over the standard G.652 fiber is obtained, opening the possibility to easily integrate in currently developed infrastructures such low cost systems operating in the first optical window.

Fifth Conference on Sensors, MEMS, and Electro-Optic Systems, 2019

A novel silicon SiGe edge light emitting diode (SiGe ELED) was realized in standard RF bipolar Si... more A novel silicon SiGe edge light emitting diode (SiGe ELED) was realized in standard RF bipolar SiGe technology process that uses a p-n junction either in reverse and forward bias mode configurations. A vertical cubical columnar SiGe/Si HBT like structure was used. The light emitting process in the reverse bias mode is by means of an avalanche breakdown process. The reverse biased device emits light in the wavelength range of 450–650 nm, with operating voltage and current of 1.3 V and 8 mA respectively, while the forward biased mode emitted at about 850nm. In the forward biased mode, it operates in a two junction mode with the first n+p junction emitting low energy electrons into a lowly doped p region. The SiGe ELED is intended to be implemented in an optical interconnect with an external detector via a lateral optical waveguide coupling. Because the LED emit in a broad spectrum, localizing the emission source point is of paramount importance. Two techniques were used to attempt to realise this objective. Optical Probe measurement and Optical Power Meter Mapping technique. Localization of the emission source point process was performed through scanning a lensed fiber coupled to an optical power meter, over the edge surface profile of the diced device. The side edge of the diced device structure was interface with the lens fibre in other to ascertain the maximum emission point and the nature of light emitting process. This was done using a smooth dicing of the LED device close to its emitting edge and scanning its edge surface through a multimode lensed fiber coupled to an optical power meter. The mapping area scanned was 40μm x 40μm and 60μ x 60μ to localize the emitting source point region. A total emitted optical power as measured from the Led was 2.86nW as measured by the optical power meter connected to the lensed optical fibre. This was confirmed with a light-current-voltage (LIV) characteristics power measurement curve obtained from the device by means of the edge mapping techniques. A rough estimated localization of the source point was approximately 0.3mW optical power with a current of 8mA was realized with this technique. These results can be used to design accurate electro-optical conversions in integrated photonic circuitry as well as designing well coupled optical interconnects from the chip to the environment.

2016 46th European Microwave Conference (EuMC), 2016

In this paper, we focus on the study of large bandwidth wireless signal transmission following a ... more In this paper, we focus on the study of large bandwidth wireless signal transmission following a 60 GHz standard over a multimode fiber link used to cover optical distribution for the last mile. To reduce the multimode effects within the fiber, a single mode fiber is first added to play a role of mode filter, and then replaced by a Mandrel as a filter. Error vector magnitude (EVM) is used as a metrics to analyze the signal degradation. Simulation results are confirmed by measurements. The EVM of the RoF links on single mode fiber, multimode fiber with and without filtering are compared.

2020 International Topical Meeting on Microwave Photonics (MWP), 2020

An efficient solution capable to meet the growing wireless traffic demand, particularly within in... more An efficient solution capable to meet the growing wireless traffic demand, particularly within in-building scenarios, is here proposed. The system matches the Radio-over-Fiber (RoF) and the Time Modulated Array (TMA) technologies, in order to achieve a capillary distribution of the radio antenna units while being able to perform an efficient beamforming to improve the wireless coverage efficiency.

IEEE Journal of Quantum Electronics, 2020

Optical transitions in silicon avalanche mode silcon LEDs were modeled, using the energy band str... more Optical transitions in silicon avalanche mode silcon LEDs were modeled, using the energy band structure, available carrier energy and momentum spreads. Based on previous experimental observations, it was hypothesized that emissions at these wavelengths can be enhanced by using a combination of excitation of carriers in high electric fields and scattering of excited carriers in compensated, high dopant impurity p+n+ environments, optical emissions at 650 and 750-850 nm wavelength emission regimes could be stimulated. A number of p+np+ devices were subsequently designed and realized using a 0.35-micron RF bipolar fabrication process that provided control over both carrier energy and carrier balancing. The optical emission characteristics of the devices was analyzed using an optical fiber lensed probe spectrophotometer and high-resolution optical microscopy. Clear evidence is obtained that 650 nm emissions can be enhanced in nano dimensioned emission spots by using these technologies. The devices operated in the 5-10V and 0.08–10mA regime. External emission intensities of up to 100 nW mutextm2\mu \text{m}^{2}mutextm2 were observed. Furthermore, using the same modeling, light emission was observed at nano-dimensioned regions emitting in the 750 - 850 nm emission region by placing high dopant impurity regions next to lowly doped high E fleld regions, and relaxing and scattering carriers in these zones. The 750 - 850 nm emissions may find application in both short haul and long haul integrated Si AMLEDs coupled to silicon nitride waveguide structures.

Journal of Lightwave Technology, 2018

In view of the realization of short and medium range Mobile Front-Haul (MFH) connections for pres... more In view of the realization of short and medium range Mobile Front-Haul (MFH) connections for present (LTE) and future (5G) cellular networks, a cost effective, low consumption Radio over Fiber system is proposed, based on 850 nm Single Mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fibers (SSMFs). An efficient countermeasure to possible impairments due to the bi-modal behavior of SSMFs at 850 nm allows even in critical cases to maintain at high level the quality of the received signal. The performances are evaluated with reference to the Physical Downlink Shared Channel of an entire LTE frame with 20 MHz bandwidth centered in band 20 of the standard. In terms of Error Vector Magnitude and outage probability under temperature stress the system is able to transmit 256-QAM signals in compliance with the LTE standard, which corresponds to a raw data rate transmission of 134.4 Mbit/s, up to distances of 1.5 km.

Electronics Letters, 2019

This Letter presents the impact of silicon substrate resistivity on SiGe phototransistors. SiGe p... more This Letter presents the impact of silicon substrate resistivity on SiGe phototransistors. SiGe phototransistors were fabricated on the commercially available SiGe/Si bipolar technology. The performances of the phototransistors fabricated based on low-and the high-resistive silicon substrate are compared. The phototransistor based on lowresistivity (LR) silicon substrate provides a responsivity of more than double compared to the phototransistor based on a high-resistivity silicon substrate that is fabricated by using the same bipolar transistor technology. The phototransistor fabricated on LR substrate exhibits low-frequency responsivity up to 1.35 A/W (at 50 MHz).

Optical Engineering, 2019

Abstract. A two-junction micro p+np+ silicon avalanche-mode light-emitting device (Si AMLED) is a... more Abstract. A two-junction micro p+np+ silicon avalanche-mode light-emitting device (Si AMLED) is analyzed for its dispersion characteristics, which generally resulted in different wavelengths of light (colors) being emitted at different angles from the surface of the device. The SiAMLED is integrated into on-chip bipolar radio frequency-integrated circuitry at micron dimensions. LEDs have high-frequency modulation frequencies reaching into the GHz range. Such devices, which are of micron dimension, operate at 8 to 10 V, 1 μA to 2 mA. The emission wavelength is in the 450- to 850-nm range, emission spot sizes are about 1 μm2, and emission intensities are up to 200 nW . μm − 2. The observed geometrical-chromatic dispersion characteristics range from 0.01 deg / nm wavelength for green radiation at a 5 deg exit angle to the normal of the device to 0.16 deg / nm wavelength for blue radiation at a 60 deg exit angle to the normal of the surface of the device. The high dispersion characteristics of the emitted radiation are attributed to the positioning of the optical source ∼1 μm subsurface to the silicon–silicon oxide interface, as well as to the high-refractive index differences between silicon and the surrounding lower refractive index silicon oxide layers. It is believed that the identified dispersion characteristics will have interesting and futuristic on-chip electro-optic applications for on-chip micro-optical wavelength dispersers, futuristic optical communication demultiplexers, along with on-chip microgas and biosensor applications.

IEEE Microwave and Wireless Components Letters, 2019

This letter unfolds a digital predistortion (DPD) technique that improves the linearity of limite... more This letter unfolds a digital predistortion (DPD) technique that improves the linearity of limited range mobile front haul links for the contemporary long-term evolution (LTE) and future (5G) networks. In particular, the proposed technique is applied to radio-over-fiber links based on single-mode (SM) vertical cavity surface emitting lasers emitting at 850 nm and standard SM fibers. Both the memory and generalized memory polynomial models are exploited for the predistorter and identified by utilizing indirect learning architecture. The impact of the DPD technique is observed by the link performance improvement in terms of normalized mean square error and adjacent channel power ratio, referring to complete LTE frames of 10 ms occupying 5-MHz bandwidth and having 64-quadrature amplitude modulation format. Furthermore, the effectiveness of the DPD approach, when varying input power levels, is investigated. The experimental results demonstrate the capability of the proposed DPD technique to achieve promising linearization performance.

Fourth Conference on Sensors, MEMS, and Electro-Optic Systems, 2017

Si Av LEDs are easily integrated in on-chip integrated circuitry. They have high modulation frequ... more Si Av LEDs are easily integrated in on-chip integrated circuitry. They have high modulation frequencies into the GHz range and can be fabricated to sub-micron dimensions. Due to subsurface light generation in the silicon device itself, and the high refractive index differences between silicon and the device environment, the exiting light radiation has interesting dispersion characteristics. Three junction micro p+-np+ Silicon Avalanche based Light Emitting Devices (Si Av LEDs) have been analyzed in terms of dispersion characteristics, generally resulting in different wavelengths of light (colors) being emitted at different angles and solid angles from the surfaces of these devices. The emission wavelength is in the 450 - 850 nm range. The devices are of micron dimension and operate at 8 - 10V, 1μA - 2mA. The emission spot sizes are about 1 micron square. Emission intensities are up to 500 nW.μm-2. The observed dispersion characteristics range from 0.05 degrees per nm per degree at emission angle of 5 degrees, to 0.15 degrees per nm at emission angles of 30 degrees. It is believed that the dispersion characteristics can find interesting and futuristic on-chip electro-optic applications involving particularly a ranging from on chip micro optical wavelength dispersers, communication de-multiplexers, and novel bio-sensor applications. All of these could penetrate into the nanoscale dimensions.

Journal of Physics: Conference Series, 2017

View the article online for updates and enhancements. Related content Optimized Pixel Design to R... more View the article online for updates and enhancements. Related content Optimized Pixel Design to Remove Disclination Lines in a Homogeneously Aligned Liquid Crystal Microdisplay Driven by a Fringe-Electric Field Je Hoon Song, Jae-Hyung Kim, Sang-Hee Nam et al.-Cmos spdt switch for wlan applications M A S Bhuiyan, M B I Reaz, L F Rahman et al.-Ultrabroadband Emission Spectrum from a Reverse-Biased 4H-SiC p-n Junction Diode

IEEE Transactions on Electron Devices, 2017

This paper proposes a novel type of compact circuit model for silicon germanium (SiGe) heterojunc... more This paper proposes a novel type of compact circuit model for silicon germanium (SiGe) heterojunction phototransistor (HPT) that is justified from the distributed nature of both its electrical and optical behaviors. The proposed model is based on a modified Ebers-Model structure and contains 28 different parameters. It is independent of the nature of the base bias (current or voltage), as opposed to existing models. The method to identify that the architecture of the model is original as it makes use of a drift-diffusion numerical simulation of a SiGe HPT adjusted to experimental data. A good fit of the model both in amplitude and phase is obtained through the nine optomicrowave S-parameters.

IEEE Journal of Quantum Electronics, 2017

600-650 nm wavelengths optical emission at have been stimulated in two-junction, monolithically i... more 600-650 nm wavelengths optical emission at have been stimulated in two-junction, monolithically integrated circuit p+-np+ Injection-Avalanche Silicon Light Emitting Devices. This has been achieved after extensive modelling of potential light emitting mechanisms that could stimulate light emission at these wavelengths. Evidence has been obtained that the optical emissions occur through short range phonon assisted inter-band transitions that occur when low energy holes are injected into avalanching junction's electrons and low energy holes recombine in energetic electrons in a high impurity/ defect density environment. Particularly, it is shown that the emission intensity depends on the balancing of densities of energetic electrons and low energy holes in this environment. The devices are of micron dimension and operate at 8-10V, 10µA-10 mA regimes. Some of the emission spot sizes are submicron. Emission intensities are typically 70nW/µm-2 /mA. The observed effect may find several applications in futuristic on-chip electro-optic applications. A third control contact terminal offers modulation possibilities.

2015 IEEE Advanced Information Technology, Electronic and Automation Control Conference (IAEAC), 2015

Silicon Avalanche-based p+nn+ Light Emitting Devices (SiAvLEDs) have been developed in a silicon ... more Silicon Avalanche-based p+nn+ Light Emitting Devices (SiAvLEDs) have been developed in a silicon 0.35 micron RF bi-polar process with emission intensities up to 200 nWμm-1. The spectral range is in the 600 nm to 850 nm wavelength region. The achieved emitted optical intensity is 100 fold better as compared with recent other published work for nearest related devices. Particularly, evidence has been obtained that light emission in silicon are strongly related to scattering mechanisms are strongly dependent on the high density n+ dopant matrix of phosphorous atoms in silicon that has been exposed to successive thermal cycles. Specific design aspects are discussed according to carrier energy and momentum engineering concepts and device modeling. Diverse sets of experimental results are presented in this regard. Some potential applications are discussed for next generation realization of various photonic circuits in standard silicon integrated circuitry. Recent achievements and progresses with the high frequency modulation of on-chip optical links using a standard RF bipolar process are discussed. Some potential applications with the realization of micro-optical sensors on silicon chips are presented.

Applied Optics, 2016

Direct modulation of a laser source is often utilized in realizing optical fiber connections wher... more Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results.

Optik - International Journal for Light and Electron Optics, 2016

In this paper, the emission of visible light (400-900 nm) by a monolithically integrated silicon ... more In this paper, the emission of visible light (400-900 nm) by a monolithically integrated silicon p-n junction under reverse bias is presented. It is theoretically deducted that these Si-LEDs can operate in GHz range and provide reliable operation. The modulation of Si-LED is verified using the existing twodimensional (2-D) models to simulate the vertical and lateral fields. With the help of Monte Carlo and Rsoft BeamPROP simulations, the vertical emission, focusing, refraction, splitting and wave-guiding are optimized in standard CMOS technology at 750 nm wavelength. Since the Si-LEDs, waveguides, and Siphoto-detector can be integrated on a single chip, a small micro-photonic system could be realized in the CMOS integrated circuitry standard platform.

2021 International Topical Meeting on Microwave Photonics (MWP), 2021

Radio over Fiber systems based on 850nm Vertical Cavity Surface Emitting Lasers constitute an att... more Radio over Fiber systems based on 850nm Vertical Cavity Surface Emitting Lasers constitute an attractive solution to realize cost-and-consumption-efficient 4G/5G Front Hauls while reusing the existing in-building G.652 fiber infrastructures. In view of such application, the mitigation of the nonlinearities of these systems through an effective local predistortion loop is demonstrated for a transmission distance of 2Km.

Journal of Lightwave Technology, 2021

This paper describes a compact and low cost optically fed antenna for using as a receiver in 5G c... more This paper describes a compact and low cost optically fed antenna for using as a receiver in 5G cellular networks and in distributed antenna systems. It compares the performance of two different topologies of patch antennas tightly integrated with vertical-cavity surface-emitting lasers (VCSELs), without the need for an amplifier stage or matching circuit. Opto-microwave (OM) gain of −21.5 dB at 5.15 GHz for the Microstrip patch antenna (MPA), and −24.2 dB at 4.8 GHz for the Grounded Coplanar patch antenna (GCPA) are achieved. The MPA architecture is quite original as it removes the need for RF feed lines through a direct injection of the signal from the patch to the VCSEL. The paper evaluates the different contributions to the total gain due to the VCSEL responsivity, the coupling between the optical fiber and the VCSEL, the wire-bonding losses and the antenna gain, with the goal of optimizing the steps at which major losses occur.

Journal of Lightwave Technology, 2021

The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, sho... more The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, showing how, particularly within In-Building scenarios, it allows to combine the pervasiveness of the first technique with the beam-steering capability of the second. A cost-effective 3-element RoF-TMA system is presented and investigated, to realize a solution for small offices / private houses (SoHos). It is confirmed that bringing the feed to the antennas through the RoF system keeps the possibility for the TMA to radiate power at different frequencies, in each case with a steerable maximum direction. Referring to mobile signals with RF carriers of few GHz, it is shown that to guarantee, for each of the multiple beams emitted by the TMA, a maximum deviation of 5 from its ideal direction, it is sufficient that among the output branches of the 1:3 optical splitter utilized the length difference is maintained in the range of a few millimeters.

2018 International Topical Meeting on Microwave Photonics (MWP), 2018

This paper presents for the first time the transmission of LTE signal based-on Radio-over-Fiber (... more This paper presents for the first time the transmission of LTE signal based-on Radio-over-Fiber (RoF) scheme by using SiGe Hetero-junction Photo-Transistor as photo-receiver. The photo-transistor is fabricated based-on the commercial bipolar transistor technology. An 850 nm single mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fiber (SSMF) are used to complete the link so that makes the total cost of the system very low. The transmission of 20 MHz bandwidth LTE signal with high modulation format is achieved. The performance of the system is evaluated through the measurement of Error Vector Magnitude (EVM) under different operation conditions of the photo-transistor (in photodiode mode, photo-transistor mode and two terminals mode). We reach an EVM below 8% for the input power of -25 dBm to -2 dBm when the photo-transistor operates under two terminals condition. This EVM value fulfills the requirements of the LTE standard for 64-QAM modulation. The stability of the system with regard temperature variation and modal noise is also presented.

2020 Italian Conference on Optics and Photonics (ICOP), 2020

Commercial couplers designed for 1550nm are conveniently adopted for realizing efficient Radio-ov... more Commercial couplers designed for 1550nm are conveniently adopted for realizing efficient Radio-over-Fiber links operating at 850nm on the standard G.652 single mode fiber. In particular, exploiting the mode filtering properties observed in these couplers when excited at 850nm, a multi-wavelength system over the standard G.652 fiber is obtained, opening the possibility to easily integrate in currently developed infrastructures such low cost systems operating in the first optical window.

Fifth Conference on Sensors, MEMS, and Electro-Optic Systems, 2019

A novel silicon SiGe edge light emitting diode (SiGe ELED) was realized in standard RF bipolar Si... more A novel silicon SiGe edge light emitting diode (SiGe ELED) was realized in standard RF bipolar SiGe technology process that uses a p-n junction either in reverse and forward bias mode configurations. A vertical cubical columnar SiGe/Si HBT like structure was used. The light emitting process in the reverse bias mode is by means of an avalanche breakdown process. The reverse biased device emits light in the wavelength range of 450–650 nm, with operating voltage and current of 1.3 V and 8 mA respectively, while the forward biased mode emitted at about 850nm. In the forward biased mode, it operates in a two junction mode with the first n+p junction emitting low energy electrons into a lowly doped p region. The SiGe ELED is intended to be implemented in an optical interconnect with an external detector via a lateral optical waveguide coupling. Because the LED emit in a broad spectrum, localizing the emission source point is of paramount importance. Two techniques were used to attempt to realise this objective. Optical Probe measurement and Optical Power Meter Mapping technique. Localization of the emission source point process was performed through scanning a lensed fiber coupled to an optical power meter, over the edge surface profile of the diced device. The side edge of the diced device structure was interface with the lens fibre in other to ascertain the maximum emission point and the nature of light emitting process. This was done using a smooth dicing of the LED device close to its emitting edge and scanning its edge surface through a multimode lensed fiber coupled to an optical power meter. The mapping area scanned was 40μm x 40μm and 60μ x 60μ to localize the emitting source point region. A total emitted optical power as measured from the Led was 2.86nW as measured by the optical power meter connected to the lensed optical fibre. This was confirmed with a light-current-voltage (LIV) characteristics power measurement curve obtained from the device by means of the edge mapping techniques. A rough estimated localization of the source point was approximately 0.3mW optical power with a current of 8mA was realized with this technique. These results can be used to design accurate electro-optical conversions in integrated photonic circuitry as well as designing well coupled optical interconnects from the chip to the environment.

2016 46th European Microwave Conference (EuMC), 2016

In this paper, we focus on the study of large bandwidth wireless signal transmission following a ... more In this paper, we focus on the study of large bandwidth wireless signal transmission following a 60 GHz standard over a multimode fiber link used to cover optical distribution for the last mile. To reduce the multimode effects within the fiber, a single mode fiber is first added to play a role of mode filter, and then replaced by a Mandrel as a filter. Error vector magnitude (EVM) is used as a metrics to analyze the signal degradation. Simulation results are confirmed by measurements. The EVM of the RoF links on single mode fiber, multimode fiber with and without filtering are compared.

2020 International Topical Meeting on Microwave Photonics (MWP), 2020

An efficient solution capable to meet the growing wireless traffic demand, particularly within in... more An efficient solution capable to meet the growing wireless traffic demand, particularly within in-building scenarios, is here proposed. The system matches the Radio-over-Fiber (RoF) and the Time Modulated Array (TMA) technologies, in order to achieve a capillary distribution of the radio antenna units while being able to perform an efficient beamforming to improve the wireless coverage efficiency.

IEEE Journal of Quantum Electronics, 2020

Optical transitions in silicon avalanche mode silcon LEDs were modeled, using the energy band str... more Optical transitions in silicon avalanche mode silcon LEDs were modeled, using the energy band structure, available carrier energy and momentum spreads. Based on previous experimental observations, it was hypothesized that emissions at these wavelengths can be enhanced by using a combination of excitation of carriers in high electric fields and scattering of excited carriers in compensated, high dopant impurity p+n+ environments, optical emissions at 650 and 750-850 nm wavelength emission regimes could be stimulated. A number of p+np+ devices were subsequently designed and realized using a 0.35-micron RF bipolar fabrication process that provided control over both carrier energy and carrier balancing. The optical emission characteristics of the devices was analyzed using an optical fiber lensed probe spectrophotometer and high-resolution optical microscopy. Clear evidence is obtained that 650 nm emissions can be enhanced in nano dimensioned emission spots by using these technologies. The devices operated in the 5-10V and 0.08–10mA regime. External emission intensities of up to 100 nW mutextm2\mu \text{m}^{2}mutextm2 were observed. Furthermore, using the same modeling, light emission was observed at nano-dimensioned regions emitting in the 750 - 850 nm emission region by placing high dopant impurity regions next to lowly doped high E fleld regions, and relaxing and scattering carriers in these zones. The 750 - 850 nm emissions may find application in both short haul and long haul integrated Si AMLEDs coupled to silicon nitride waveguide structures.

Journal of Lightwave Technology, 2018

In view of the realization of short and medium range Mobile Front-Haul (MFH) connections for pres... more In view of the realization of short and medium range Mobile Front-Haul (MFH) connections for present (LTE) and future (5G) cellular networks, a cost effective, low consumption Radio over Fiber system is proposed, based on 850 nm Single Mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fibers (SSMFs). An efficient countermeasure to possible impairments due to the bi-modal behavior of SSMFs at 850 nm allows even in critical cases to maintain at high level the quality of the received signal. The performances are evaluated with reference to the Physical Downlink Shared Channel of an entire LTE frame with 20 MHz bandwidth centered in band 20 of the standard. In terms of Error Vector Magnitude and outage probability under temperature stress the system is able to transmit 256-QAM signals in compliance with the LTE standard, which corresponds to a raw data rate transmission of 134.4 Mbit/s, up to distances of 1.5 km.

Electronics Letters, 2019

This Letter presents the impact of silicon substrate resistivity on SiGe phototransistors. SiGe p... more This Letter presents the impact of silicon substrate resistivity on SiGe phototransistors. SiGe phototransistors were fabricated on the commercially available SiGe/Si bipolar technology. The performances of the phototransistors fabricated based on low-and the high-resistive silicon substrate are compared. The phototransistor based on lowresistivity (LR) silicon substrate provides a responsivity of more than double compared to the phototransistor based on a high-resistivity silicon substrate that is fabricated by using the same bipolar transistor technology. The phototransistor fabricated on LR substrate exhibits low-frequency responsivity up to 1.35 A/W (at 50 MHz).

Optical Engineering, 2019

Abstract. A two-junction micro p+np+ silicon avalanche-mode light-emitting device (Si AMLED) is a... more Abstract. A two-junction micro p+np+ silicon avalanche-mode light-emitting device (Si AMLED) is analyzed for its dispersion characteristics, which generally resulted in different wavelengths of light (colors) being emitted at different angles from the surface of the device. The SiAMLED is integrated into on-chip bipolar radio frequency-integrated circuitry at micron dimensions. LEDs have high-frequency modulation frequencies reaching into the GHz range. Such devices, which are of micron dimension, operate at 8 to 10 V, 1 μA to 2 mA. The emission wavelength is in the 450- to 850-nm range, emission spot sizes are about 1 μm2, and emission intensities are up to 200 nW . μm − 2. The observed geometrical-chromatic dispersion characteristics range from 0.01 deg / nm wavelength for green radiation at a 5 deg exit angle to the normal of the device to 0.16 deg / nm wavelength for blue radiation at a 60 deg exit angle to the normal of the surface of the device. The high dispersion characteristics of the emitted radiation are attributed to the positioning of the optical source ∼1 μm subsurface to the silicon–silicon oxide interface, as well as to the high-refractive index differences between silicon and the surrounding lower refractive index silicon oxide layers. It is believed that the identified dispersion characteristics will have interesting and futuristic on-chip electro-optic applications for on-chip micro-optical wavelength dispersers, futuristic optical communication demultiplexers, along with on-chip microgas and biosensor applications.

IEEE Microwave and Wireless Components Letters, 2019

This letter unfolds a digital predistortion (DPD) technique that improves the linearity of limite... more This letter unfolds a digital predistortion (DPD) technique that improves the linearity of limited range mobile front haul links for the contemporary long-term evolution (LTE) and future (5G) networks. In particular, the proposed technique is applied to radio-over-fiber links based on single-mode (SM) vertical cavity surface emitting lasers emitting at 850 nm and standard SM fibers. Both the memory and generalized memory polynomial models are exploited for the predistorter and identified by utilizing indirect learning architecture. The impact of the DPD technique is observed by the link performance improvement in terms of normalized mean square error and adjacent channel power ratio, referring to complete LTE frames of 10 ms occupying 5-MHz bandwidth and having 64-quadrature amplitude modulation format. Furthermore, the effectiveness of the DPD approach, when varying input power levels, is investigated. The experimental results demonstrate the capability of the proposed DPD technique to achieve promising linearization performance.

Fourth Conference on Sensors, MEMS, and Electro-Optic Systems, 2017

Si Av LEDs are easily integrated in on-chip integrated circuitry. They have high modulation frequ... more Si Av LEDs are easily integrated in on-chip integrated circuitry. They have high modulation frequencies into the GHz range and can be fabricated to sub-micron dimensions. Due to subsurface light generation in the silicon device itself, and the high refractive index differences between silicon and the device environment, the exiting light radiation has interesting dispersion characteristics. Three junction micro p+-np+ Silicon Avalanche based Light Emitting Devices (Si Av LEDs) have been analyzed in terms of dispersion characteristics, generally resulting in different wavelengths of light (colors) being emitted at different angles and solid angles from the surfaces of these devices. The emission wavelength is in the 450 - 850 nm range. The devices are of micron dimension and operate at 8 - 10V, 1μA - 2mA. The emission spot sizes are about 1 micron square. Emission intensities are up to 500 nW.μm-2. The observed dispersion characteristics range from 0.05 degrees per nm per degree at emission angle of 5 degrees, to 0.15 degrees per nm at emission angles of 30 degrees. It is believed that the dispersion characteristics can find interesting and futuristic on-chip electro-optic applications involving particularly a ranging from on chip micro optical wavelength dispersers, communication de-multiplexers, and novel bio-sensor applications. All of these could penetrate into the nanoscale dimensions.

Journal of Physics: Conference Series, 2017

View the article online for updates and enhancements. Related content Optimized Pixel Design to R... more View the article online for updates and enhancements. Related content Optimized Pixel Design to Remove Disclination Lines in a Homogeneously Aligned Liquid Crystal Microdisplay Driven by a Fringe-Electric Field Je Hoon Song, Jae-Hyung Kim, Sang-Hee Nam et al.-Cmos spdt switch for wlan applications M A S Bhuiyan, M B I Reaz, L F Rahman et al.-Ultrabroadband Emission Spectrum from a Reverse-Biased 4H-SiC p-n Junction Diode

IEEE Transactions on Electron Devices, 2017

This paper proposes a novel type of compact circuit model for silicon germanium (SiGe) heterojunc... more This paper proposes a novel type of compact circuit model for silicon germanium (SiGe) heterojunction phototransistor (HPT) that is justified from the distributed nature of both its electrical and optical behaviors. The proposed model is based on a modified Ebers-Model structure and contains 28 different parameters. It is independent of the nature of the base bias (current or voltage), as opposed to existing models. The method to identify that the architecture of the model is original as it makes use of a drift-diffusion numerical simulation of a SiGe HPT adjusted to experimental data. A good fit of the model both in amplitude and phase is obtained through the nine optomicrowave S-parameters.

IEEE Journal of Quantum Electronics, 2017

600-650 nm wavelengths optical emission at have been stimulated in two-junction, monolithically i... more 600-650 nm wavelengths optical emission at have been stimulated in two-junction, monolithically integrated circuit p+-np+ Injection-Avalanche Silicon Light Emitting Devices. This has been achieved after extensive modelling of potential light emitting mechanisms that could stimulate light emission at these wavelengths. Evidence has been obtained that the optical emissions occur through short range phonon assisted inter-band transitions that occur when low energy holes are injected into avalanching junction's electrons and low energy holes recombine in energetic electrons in a high impurity/ defect density environment. Particularly, it is shown that the emission intensity depends on the balancing of densities of energetic electrons and low energy holes in this environment. The devices are of micron dimension and operate at 8-10V, 10µA-10 mA regimes. Some of the emission spot sizes are submicron. Emission intensities are typically 70nW/µm-2 /mA. The observed effect may find several applications in futuristic on-chip electro-optic applications. A third control contact terminal offers modulation possibilities.

2015 IEEE Advanced Information Technology, Electronic and Automation Control Conference (IAEAC), 2015

Silicon Avalanche-based p+nn+ Light Emitting Devices (SiAvLEDs) have been developed in a silicon ... more Silicon Avalanche-based p+nn+ Light Emitting Devices (SiAvLEDs) have been developed in a silicon 0.35 micron RF bi-polar process with emission intensities up to 200 nWμm-1. The spectral range is in the 600 nm to 850 nm wavelength region. The achieved emitted optical intensity is 100 fold better as compared with recent other published work for nearest related devices. Particularly, evidence has been obtained that light emission in silicon are strongly related to scattering mechanisms are strongly dependent on the high density n+ dopant matrix of phosphorous atoms in silicon that has been exposed to successive thermal cycles. Specific design aspects are discussed according to carrier energy and momentum engineering concepts and device modeling. Diverse sets of experimental results are presented in this regard. Some potential applications are discussed for next generation realization of various photonic circuits in standard silicon integrated circuitry. Recent achievements and progresses with the high frequency modulation of on-chip optical links using a standard RF bipolar process are discussed. Some potential applications with the realization of micro-optical sensors on silicon chips are presented.

Applied Optics, 2016

Direct modulation of a laser source is often utilized in realizing optical fiber connections wher... more Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results.

Optik - International Journal for Light and Electron Optics, 2016

In this paper, the emission of visible light (400-900 nm) by a monolithically integrated silicon ... more In this paper, the emission of visible light (400-900 nm) by a monolithically integrated silicon p-n junction under reverse bias is presented. It is theoretically deducted that these Si-LEDs can operate in GHz range and provide reliable operation. The modulation of Si-LED is verified using the existing twodimensional (2-D) models to simulate the vertical and lateral fields. With the help of Monte Carlo and Rsoft BeamPROP simulations, the vertical emission, focusing, refraction, splitting and wave-guiding are optimized in standard CMOS technology at 750 nm wavelength. Since the Si-LEDs, waveguides, and Siphoto-detector can be integrated on a single chip, a small micro-photonic system could be realized in the CMOS integrated circuitry standard platform.