Richard Schatz | KTH Royal Institute of Technology (original) (raw)
Papers by Richard Schatz
IEEE Transactions on Microwave Theory and Techniques, 2001
We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud... more We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud per lane and scalable to 1.6 Tb/s capacity and beyond for next generation 51.2T and 102.4T digital switches.
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
We propose a low complexity timing algorithm for high order PAM. Experimental results demonstrate... more We propose a low complexity timing algorithm for high order PAM. Experimental results demonstrate higher performance and lower complexity than conventional algorithms in a 32 Gbaud PAM-8 transmission over 4 km SMF links.
IEEE Photonics Technology Letters, May 1, 2023
European Conference on Optical Communication, 2004
ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive... more ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive technique for encoding information in the output of a semiconductor laser. The growing requirements in volume of information to be transmitted and their conflict with the progressive, and rapid, degradation of the signal at high speeds have made this simple technical solution less and less attractive. A brief analysis of the sources of the problem is offered. A viable and inexpensive way of improving DM's performance is discussed. High quality signals are predicted at data transmission speeds that exceed by over an order of magnitude those obtainable with DM.
We summarize our recent research works on enabling coherent optical transmission systems for metr... more We summarize our recent research works on enabling coherent optical transmission systems for metro and access networks with low-complexity digital signal processing techniques, focusing on reduction of laser linewidth requirement with efficient carrier phase recovery.
We demonstrate the significant impact of crosstalk between add and drop ports at optical nodes on... more We demonstrate the significant impact of crosstalk between add and drop ports at optical nodes on energy-efficiency per Hertz in WDM networks employing 32/64 Gbd DP-16QAM transmission, especially when the isolation is reduced to 30dB.
We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.... more We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.3-0.5 THz) and upper- (~64.5 THz) terahertz bands. We adopt the hybrid electro-optical approach for the lower-THz signal transmission, whereas a directly modulated quantum cascade laser is used for the upper-THz band.
European Conference on Optical Communication, 2016
We report on the first experimental demonstration of 100Gbit/s 3-level duobinary optical transmis... more We report on the first experimental demonstration of 100Gbit/s 3-level duobinary optical transmission enabled by in-house newly developed SiGe BiCMOS transmitter/receiver ICs. Operated in real-time, we demonstrated a 100Gbit/s data-rate over 2km SSMF without DSP.
We demonstrate 100 Gbaud 4PAM transmission over 400 meters SMF with monolithically integrated 155... more We demonstrate 100 Gbaud 4PAM transmission over 400 meters SMF with monolithically integrated 1550 nm DFB-TWEAM having 100 GHz 3-dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable two lanes 400 GbE client-side links for optical interconnects.
Journal of Lightwave Technology, 1993
We investigated the fluorescence characteristics of the bismuth doped silica fibers with and with... more We investigated the fluorescence characteristics of the bismuth doped silica fibers with and without Al co-dopant which are fabricated by means of modified chemical vapour deposition (MCVD) technique. It was found that the bismuth and germanium codoped silica fiber exhibited a strong broad infrared emission centring at 1450 nm and covering 1300 nm when excited by the laser diodes working at 808 nm and 976 nm respectively. It was also found that for the Al and bismuth codoped silica fiber, the red (centring around 750 nm) and the infrared fluorescence (centring around 1100 nm) may originate from different emission centers in the fiber. Furthermore, strong up-conversion luminescence was also observed in both Al codoped and non-Al codoped bismuth doped fibers when the fibers were excited by an acoustic-optic Q-switched Nd:YVO 4 laser. It is thus concluded that the upper energy level absorption reported in the work of the bismuth doped silica fiber lasers may result from the fluorescence emission sites not responsible for the infrared emission.
Optics Express, Feb 14, 2023
High bitrate mid-infrared links using simple (NRZ) and multi-level (PAM-4) data coding schemes ha... more High bitrate mid-infrared links using simple (NRZ) and multi-level (PAM-4) data coding schemes have been realized in the 8 µm to 14 µm atmospheric transparency window. The free space optics system is composed of unipolar quantum optoelectronic devices, namely a continuous wave quantum cascade laser, an external Stark-effect modulator and a quantum cascade detector, all operating at room-temperature. Pre- and post-processing are implemented to get enhanced bitrates, especially for PAM-4 where inter-symbol interference and noise are particularly detrimental to symbol demodulation. By exploiting these equalization procedures, our system, with a full frequency cutoff of 2 GHz, has reached transmission bitrates of 12 Gbit/s NRZ and 11 Gbit/s PAM-4 fulfilling the 6.25 % overhead hard-decision forward error correction threshold, limited only by the low signal-to-noise ratio of our detector.
By employing enhanced DPCM, 15-Gbaud PAM4 digital mobile fronthaul is experimentally demonstrated... more By employing enhanced DPCM, 15-Gbaud PAM4 digital mobile fronthaul is experimentally demonstrated to support 122 LTE-A channels with up to 4096QAM. Compared to PCM based CPRI, the supported number of channels increases 5 times and EVM is obviously improved.
The cloud services together with the huge size datasets are driving demand for bandwidth in datac... more The cloud services together with the huge size datasets are driving demand for bandwidth in datacenters [1]. The 400 Gbps client-side links are demanding cost efficient solution: to reduce the number of lanes and increase the bandwidth for a single lane. The intensity modulation and direct-detection systems together with integrated semiconductor lasers and modulators appear as promising solution in four optical lanes at 100G since it reduces complexity, power consumption and costs [2]. However, it requires silicon and InP opto-electronic components with more than 70 GHz bandwidth [3]. In this talk, we report on a cost-efficient integrated externally modulated laser (EML) with high bandwidth for record high-speed intensity modulation and direct detection system demonstration with up to 100G OOK, PAM4/8 and duobinary signaling, as well as analog modulations e.g. DMT, paving the way for high speed multilevel modulation formats [4–6]. Related techniques including digital signal processing algorithms for timing recovery, adaptive/static equalization are also discussed in terms of practical implementation and complexity. In addition, techniques constructively using time domain super-Nyquist image induced aliasing for mitigating modulator driver nonlinearity for high speed DMT transmission will be presented [6], [7].
We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical sys... more We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical system for all practical electronic dispersion compensation configurations. It is shown that there are only eight practicable all-electronic impairment mitigation configurations. The non-linear and time variant analysis reveals that the existence and the cause of EEPN depend on the digital signal processing (DSP) schemes. There are three schemes that in principle do not cause EEPN. Analysis further reveals the statistical equivalence of the remaining five system configurations resulting in EEPN. In three of them, EEPN is due to phase noise of the transmitting laser, while in the remaining two, EEPN is caused by the local oscillator. We provide a simple look-up table for the system designer to make an informative decision regarding practicable configuration choice and design.
Proceedings of SPIE, Apr 21, 2006
ABSTRACT A packaged high speed reflective electroabsorption transceivers for radio-over-fiber app... more ABSTRACT A packaged high speed reflective electroabsorption transceivers for radio-over-fiber applications is demonstrated. The transceiver, an AFPMD (Asymmetric vertically addressed Fabry-Perot Modulator/Detector), is successfully packaged into a standard module, originally intended for 10 Gbit/s Ethernet detectors. The packaging process and the electrical, optical and thermal performance of the packaged component are presented. A bandwidth of 6 GHz, a total reflective optical coupling loss of 7.1 dB and a responsitivity of 0.14 mA/mW are accomplished. By optimizing the operation optical wavelength and bias voltage, fifth-order nonlinearity dominates the intermodulation distortion and a spurious free dynamic range (SFDR) of 101dB.Hz4/5 at 5.554GHz can be achieved experimentally.
IEEE Transactions on Microwave Theory and Techniques, 2001
We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud... more We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud per lane and scalable to 1.6 Tb/s capacity and beyond for next generation 51.2T and 102.4T digital switches.
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
We propose a low complexity timing algorithm for high order PAM. Experimental results demonstrate... more We propose a low complexity timing algorithm for high order PAM. Experimental results demonstrate higher performance and lower complexity than conventional algorithms in a 32 Gbaud PAM-8 transmission over 4 km SMF links.
IEEE Photonics Technology Letters, May 1, 2023
European Conference on Optical Communication, 2004
ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive... more ABSTRACT Direct modulation of the injected current still represents an attractive and inexpensive technique for encoding information in the output of a semiconductor laser. The growing requirements in volume of information to be transmitted and their conflict with the progressive, and rapid, degradation of the signal at high speeds have made this simple technical solution less and less attractive. A brief analysis of the sources of the problem is offered. A viable and inexpensive way of improving DM's performance is discussed. High quality signals are predicted at data transmission speeds that exceed by over an order of magnitude those obtainable with DM.
We summarize our recent research works on enabling coherent optical transmission systems for metr... more We summarize our recent research works on enabling coherent optical transmission systems for metro and access networks with low-complexity digital signal processing techniques, focusing on reduction of laser linewidth requirement with efficient carrier phase recovery.
We demonstrate the significant impact of crosstalk between add and drop ports at optical nodes on... more We demonstrate the significant impact of crosstalk between add and drop ports at optical nodes on energy-efficiency per Hertz in WDM networks employing 32/64 Gbd DP-16QAM transmission, especially when the isolation is reduced to 30dB.
We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.... more We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.3-0.5 THz) and upper- (~64.5 THz) terahertz bands. We adopt the hybrid electro-optical approach for the lower-THz signal transmission, whereas a directly modulated quantum cascade laser is used for the upper-THz band.
European Conference on Optical Communication, 2016
We report on the first experimental demonstration of 100Gbit/s 3-level duobinary optical transmis... more We report on the first experimental demonstration of 100Gbit/s 3-level duobinary optical transmission enabled by in-house newly developed SiGe BiCMOS transmitter/receiver ICs. Operated in real-time, we demonstrated a 100Gbit/s data-rate over 2km SSMF without DSP.
We demonstrate 100 Gbaud 4PAM transmission over 400 meters SMF with monolithically integrated 155... more We demonstrate 100 Gbaud 4PAM transmission over 400 meters SMF with monolithically integrated 1550 nm DFB-TWEAM having 100 GHz 3-dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable two lanes 400 GbE client-side links for optical interconnects.
Journal of Lightwave Technology, 1993
We investigated the fluorescence characteristics of the bismuth doped silica fibers with and with... more We investigated the fluorescence characteristics of the bismuth doped silica fibers with and without Al co-dopant which are fabricated by means of modified chemical vapour deposition (MCVD) technique. It was found that the bismuth and germanium codoped silica fiber exhibited a strong broad infrared emission centring at 1450 nm and covering 1300 nm when excited by the laser diodes working at 808 nm and 976 nm respectively. It was also found that for the Al and bismuth codoped silica fiber, the red (centring around 750 nm) and the infrared fluorescence (centring around 1100 nm) may originate from different emission centers in the fiber. Furthermore, strong up-conversion luminescence was also observed in both Al codoped and non-Al codoped bismuth doped fibers when the fibers were excited by an acoustic-optic Q-switched Nd:YVO 4 laser. It is thus concluded that the upper energy level absorption reported in the work of the bismuth doped silica fiber lasers may result from the fluorescence emission sites not responsible for the infrared emission.
Optics Express, Feb 14, 2023
High bitrate mid-infrared links using simple (NRZ) and multi-level (PAM-4) data coding schemes ha... more High bitrate mid-infrared links using simple (NRZ) and multi-level (PAM-4) data coding schemes have been realized in the 8 µm to 14 µm atmospheric transparency window. The free space optics system is composed of unipolar quantum optoelectronic devices, namely a continuous wave quantum cascade laser, an external Stark-effect modulator and a quantum cascade detector, all operating at room-temperature. Pre- and post-processing are implemented to get enhanced bitrates, especially for PAM-4 where inter-symbol interference and noise are particularly detrimental to symbol demodulation. By exploiting these equalization procedures, our system, with a full frequency cutoff of 2 GHz, has reached transmission bitrates of 12 Gbit/s NRZ and 11 Gbit/s PAM-4 fulfilling the 6.25 % overhead hard-decision forward error correction threshold, limited only by the low signal-to-noise ratio of our detector.
By employing enhanced DPCM, 15-Gbaud PAM4 digital mobile fronthaul is experimentally demonstrated... more By employing enhanced DPCM, 15-Gbaud PAM4 digital mobile fronthaul is experimentally demonstrated to support 122 LTE-A channels with up to 4096QAM. Compared to PCM based CPRI, the supported number of channels increases 5 times and EVM is obviously improved.
The cloud services together with the huge size datasets are driving demand for bandwidth in datac... more The cloud services together with the huge size datasets are driving demand for bandwidth in datacenters [1]. The 400 Gbps client-side links are demanding cost efficient solution: to reduce the number of lanes and increase the bandwidth for a single lane. The intensity modulation and direct-detection systems together with integrated semiconductor lasers and modulators appear as promising solution in four optical lanes at 100G since it reduces complexity, power consumption and costs [2]. However, it requires silicon and InP opto-electronic components with more than 70 GHz bandwidth [3]. In this talk, we report on a cost-efficient integrated externally modulated laser (EML) with high bandwidth for record high-speed intensity modulation and direct detection system demonstration with up to 100G OOK, PAM4/8 and duobinary signaling, as well as analog modulations e.g. DMT, paving the way for high speed multilevel modulation formats [4–6]. Related techniques including digital signal processing algorithms for timing recovery, adaptive/static equalization are also discussed in terms of practical implementation and complexity. In addition, techniques constructively using time domain super-Nyquist image induced aliasing for mitigating modulator driver nonlinearity for high speed DMT transmission will be presented [6], [7].
We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical sys... more We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical system for all practical electronic dispersion compensation configurations. It is shown that there are only eight practicable all-electronic impairment mitigation configurations. The non-linear and time variant analysis reveals that the existence and the cause of EEPN depend on the digital signal processing (DSP) schemes. There are three schemes that in principle do not cause EEPN. Analysis further reveals the statistical equivalence of the remaining five system configurations resulting in EEPN. In three of them, EEPN is due to phase noise of the transmitting laser, while in the remaining two, EEPN is caused by the local oscillator. We provide a simple look-up table for the system designer to make an informative decision regarding practicable configuration choice and design.
Proceedings of SPIE, Apr 21, 2006
ABSTRACT A packaged high speed reflective electroabsorption transceivers for radio-over-fiber app... more ABSTRACT A packaged high speed reflective electroabsorption transceivers for radio-over-fiber applications is demonstrated. The transceiver, an AFPMD (Asymmetric vertically addressed Fabry-Perot Modulator/Detector), is successfully packaged into a standard module, originally intended for 10 Gbit/s Ethernet detectors. The packaging process and the electrical, optical and thermal performance of the packaged component are presented. A bandwidth of 6 GHz, a total reflective optical coupling loss of 7.1 dB and a responsitivity of 0.14 mA/mW are accomplished. By optimizing the operation optical wavelength and bias voltage, fifth-order nonlinearity dominates the intermodulation distortion and a spurious free dynamic range (SFDR) of 101dB.Hz4/5 at 5.554GHz can be achieved experimentally.