Optical Filters Research Papers - Academia.edu (original) (raw)

2025

The production of computer-generated video presents a number of difficulties not encountered with motion pietures. Interlaced scanning and the color subcarrier of NTSC video are responsible for special problems such as interline flicker, and chroma aliasing. As in motion pictures, temporal aliasing is also an issue. A renderer can sample and filter a moving image in an arbitrary manner and is not constrained to simply imitate the behavior of a television camera. This paper explores several different spatiotemporal antialiasing filters and how they affect the quality of video animation.

2025, IEEE Photonics Technology Letters

A novel all-optical 2R regenerator based on a multimode interference coupler (MMI) semiconductor optical amplifier is presented. Static measurements of the transfer function reveal a digital transfer characteristic and a high increase in extinction ratio. The experiments are in good agreement with simulations, which have been done using a modified beam propagation method program. The device has a high tolerance to the MMI length. It has been fabricated in an all-active layout, avoiding the need for active/passive integration and is very compact.

2025, IEEE Photonics Technology Letters

2025, Thin Solid Films

For real time ellipsometry monitoring, the choice of measurement of wavelength can be advantageously adapted to the controlled parameter. Adapted wavelength ellipsometry is illustrated here by two examples. Firstly, a simple method based on the choice of an appropriate wavelength for thickness control is presented. This method requires no information on the underlaying structure and is well suited to control deposition of multilayer stacks such as Bragg reflectors. Examples of fabrication control are presented. Secondly, we report results of temperature measurements. Semiconductor spectroscopic ellipsometry had shown that there is a wavelength range within which the optical response is relatively insensitive to temperature and that there are other wavelengths in which it is highly sensitive. Thus, according to the wavelength, ellipsometry can be used to measure temperature, or, to measure other parameters taking the temperature effect into account.

2025, Chinese Optics Letters

By using PDM-OFDM-16QAM modulation, all-Raman amplification, coherent detection, and 7% forward error correction (FEC) threshold, we successfully demonstrate 63-Tb/s (368×183.3-Gb/s) signal over 160km standard single mode fiber (SSMF) transmission in the C-and L-bands with 25-GHz channel spacing. 368 optical channels with bandwidth spacing of 25 GHz are generated from 16 external cavity laser sources. After 160-km SSMF transmission, all tested bit error rate (BER) are under 3.8×10-3, which can be recovered by 7% FEC threshold. Within each channel, we achieve the spectral efficiency of 6.85 bit/s/Hz in C/L band.

2025, Optical Fiber Communication Conference

We report full C-band tunable, 10 Gbit/s capability, directly modulated MEMS-VCSEL for next generation converged mobile fronthaul and backhaul applications. Bit error rates below 10 -9 were achieved over up to 40 km SSMF.

2025, Arxiv preprint astro-ph/ …

The ALHAMBRA-Survey is a project to gather the data necessary to sample a cosmologically significant fraction of the Universe with enough precision to follow the evolution of its content and properties with z, a kind of Cosmic Tomography. It is defined as a large area, 4 • , photometric survey with 20 contiguous, equal width, medium band filters covering from 3500 Å to 9700 Å, plus the standard JHK s near-infrared bands. The photometric system in the optical was optimized to get (for a fixed amount of total observing time) the maximum number of objects with accurate classification and redshift and to be 1 sensitive to relatively faint emission features in the spectrum. We expect to be able to detect emission features down to EW = 35 Å, for S/N ≈ 30. The observations will be carried out with the 3.5m telescope in Calar Alto (Spain) using the new wide field cameras in the optical (LAICA) and in the NIR (OMEGA-2000). We intend to reach the limit AB = 25 mag (for an unresolved object, S/N=5) in all the optical filters from the bluest to 8300 Å, and from 24.7 to 23.4 for the remainder. The expected limit in the NIR is fixed at K s = 20 mag, H = 21 mag, J = 22 mag. The homogeneous and contiguous spectral coverage will result in several hundred thousand objects with accurate SED identification and z-values. The accuracy of the survey will allow us to study, among others, the large scale structure evolution with z, the identification of clusters of galaxies (with membership assessment for a significant fraction of the galaxies), the identification of families of objects, and other detailed studies, without the need for any further follow-up. Indeed, it will provide exciting targets for large telescopes, the GTC in particular. Given its area and spectral coverage and its depth, apart from those main goals, the ALHAMBRA-Survey will also produce valuable data for galactic studies.

2025, CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005.

2025, American Journal of Applied Sciences

Demosaicing is a process of obtaining a full color image by interpolating the missing colors of an image captured from a digital still and video cameras that use a single-sensor array.The edges are not handled properly in the existing demosaicking methods. This study provides an effective demosaicing algorithm applying an adaptive weighted-edge interpolation to handle green pixels. Due to the introduction of adaptive threshold based on the high frequency information for the classification of edges and textures, the interpolation of edges is performed excellently. Adaptive weights depending on spatial and spectral correlation are assigned for interpolation on both edges and smooth region. A refinement scheme based on enhanced effective color interpolation is used to improve the red and blue interpolation to obtain better quality image. As compared with the latest demosaicing algorithms, the proposed algorithm produces the best average demosaicing performance both objectively and subjectively. This approach handles the edges in a proper way and reconstructs the color image with best peak signal to noise ratio.

2025, Journal of Lightwave Technology

We investigate 40-Gb/s cost-efficient transmitter for access and metro networks. This 40-Gb/s transmitter comprises a standard directly modulated distributed-feedback (DFB) laser and a subsequent optical filter. Large dispersion tolerance of this transmitter is realized by chirp control through the phase correlation between adjacent bits for the destructive interference in order to erase the power of "0" bits while enhancing the extinction ratio. The chirp model of the DFB laser and the optimum parameters of the optical filter have been numerically analyzed. The chirp-managed 42.8-Gb/s transmission over 20-km standard single mode fiber (SSMF or SMF-28) without dispersion compensation and a centralized lightwave WDM-PON system are experimentally demonstrated. We have also realized the transmission over 100-m graded index plastic optical fiber (GI-POF). Moreover, the application in the metro network over 240-km SSMF or SMF-28 has also been investigated in this paper.

2025, The European Physical Journal Applied Physics

An infrared heat reflecting multilayer thin film filter comprising alternate layers of ZrO2 and SiO2 has been modeled and prepared on a BK7 glass substrate using RF-magnetron sputtering. Initially, the individual films of the used materials have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) for structural and surface quality prior to the deposition of multilayer structure. Spectral analysis showed that the filter has an average transmission of greater than 90% in 450 to 700 nm range and less than 2% in 700-1100 nm band fulfilling the design requirements. The XRD study of multilayer structure showed few peaks of ZrO2 along with a solitary peak for SiO2 indicating some crystallinity for ZrO2 layers in the structure. Hardness analysis showed that the initial phase of the indentation is predominantly ductile with gradual transition in behaviour from ductile to brittle with increased penetration. Interface analysis of multilayered structure was carried out by Rutherford back scattering using Tandem 5 MeV ion accelerator, showed that interfaces formed in the multilayer structure are sharp and no substantial evidence of interlayer diffusion or mixing at the interfaces.

2025, Applied Optics

Relationships between visibility and an extinction coefficient that is due to fog in optical windows that are free from molecular absorption are derived. The extinction coefficients in the visible ͑0.55 m͒, the near IR ͑1.2 m͒, and the mid IR ͑3.7 m͒ are comparable to and roughly twice as much as that in the far IR ͑10.6 m͒ when visibility is less than a few hundred meters. The advantage of far-IR radiation compared with shorter wavelengths grows as visibility exceeds 500 m. Correspondingly, the relationship between extinction coefficient and visibility becomes more sensitive to variations in the particle-size distribution of fog.

2025, SPIE Proceedings

Chiral nematic liquid crystals have attracted substantial interest. They spontaneously self-organize to form a helical structure with no complex fabrication procedure required and exhibit a reflection band for a certain wavelength interval. Since the photonic band gap can be tuned by applying external factors (heat, voltage, light, elasticity) chiral nematic liquid crystals are potentially interesting for large area optical filters and shutters, reflective displays and tunable lasers. In this work, a device which consists of a mixture of photo-polymerizable liquid crystal, non-reactive nematic liquid crystal and a chiral dopant is fabricated. By selecting the appropriate chiral dopant concentration, it is possible to make devices for different operation wavelengths. The influence of UV illumination on a partially polymerized chiral liquid crystal is investigated. A blue-wavelength shift of the photonic band gap is obtained as a function of power, duration time of UV illumination and the thickness of the cells. Interestingly the width and depth of the photonic band gap is unaffected by the change in UV curing conditions, which indicates that there is no degradation by the UV light.

2025, Optical Engineering

Liquid crystals are nowadays widely used in all types of display applications. However their unique electro-optic properties also make them a suitable material for nondisplay applications. We will focus on the use of liquid crystals in different photonic components: optical filters and switches, beam-steering devices, spatial light modulators, integrated devices based on optical waveguiding, lasers, and optical nonlinear components. Both the basic operating principles as well as the recent state-of-the art are discussed. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

2025, Ground-based and Airborne Telescopes III

During the last years, a number of telescopes and instruments have been dedicated to the follow-up of GRBs: recent studies of the prompt emission (see for instance GRB080319B) and of their afterglows, evidenced a series of phenomena that do not fit very well within the standard fireball model. In those cases, optical observations were fundamental to distinguish among different emission mechanisms and models. In particular, simultaneous observation in various optical filters became essential to understand the physics, and we discovered the need to have a detailed high time resolution *

2025, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V

MUSIC (Multicolor Submillimeter kinetic Inductance Camera) is a new facility instrument for the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) developed as a collaborative effect of Caltech, JPL, the University of Colorado at Boulder and UC Santa Barbara, and is due for initial commissioning in early 2011. MUSIC utilizes a new class of superconducting photon detectors known as microwave kinetic inductance detectors (MKIDs), an emergent technology that offers considerable advantages over current types of detectors for submillimeter and millimeter direct detection. MUSIC will operate a focal plane of 576 spatial pixels, where each pixel is a slot line antenna coupled to multiple detectors through on-chip, lumped-element filters, allowing simultaneously imaging in four bands at 0.86, 1.02, 1.33 and 2.00 mm. The MUSIC instrument is designed for closed-cycle operation, combining a pulse tube cooler with a two-stage Helium-3 adsorption refrigerator, providing a focal plane temperature of 0.25 K with intermediate temperature stages at approximately 50, 4 and 0.4 K for buffering heat loads and heat sinking of optical filters. Detector readout is achieved using semi-rigid coaxial cables from room temperature to the focal plane, with cryogenic HEMT amplifiers operating at 4 K. Several hundred detectors may be multiplexed in frequency space through one signal line and amplifier. This paper discusses the design of the instrument cryogenic hardware, including a number of features unique to the implementation of superconducting detectors. Predicted performance data for the instrument system will also be presented and discussed.

2025, CLEO:2011 - Laser Applications to Photonic Applications

A photonic ADC based on balanced detection, phase encoded optical sampling, wavelength multiplexing, and electronic quantization is demonstrated. It achieves 7.0 ENOB resolution at a 2GSa/s sub-sampling rate for a 40 GHz input analog... more

2025

The generation of flat top pulse with 10 ps duration at 266 nm, is of extreme importance to achieve low emittance electron beam from a photoinjector. The production of this pulse shape is carried out using manipulation in the frequency domain with the aid of new programmable pulse shapers. In this paper we present the experimental measurements we performed to characterize two pulse shapers: the acousto-optics filter, namely the DAZZLER, and the liquid crystal mask spatial light modulator. The measurement have been performed with the amplified Ti:Sa laser system used to drive the SPARC photoinjector at LNF-INFN. The results obtained, the operation and the main limitations of the two techniques are also presented.

2025, arXiv (Cornell University)

Using a compact optically-pumped silicon nanophotonic chip consisting of coupled silicon microrings, we generate photon pairs in multiple pairs of wavelengths around 1.55 µm. The wavelengths are tunable over several nanometers, demonstrating the capability to generate wavelength division multiplexed photon pairs at freely-chosen telecommunications-band wavelengths.

2025, The Astrophysical Journal

We identify 3,113 highly variable objects in 7,200 square degrees of the Palomar-QUEST Survey, which each varied by more than 0.4 magnitudes simultaneously in two broadband optical filters on timescales from hours to roughly 3.5 years. The primary goal of the selection is to find blazars by their well-known violent optical variability. Because most known blazars have been found in radio and/or X-ray wavelengths, a sample discovered through optical variability may have very different selection effects, elucidating the range of behavior possible in these systems. A set of blazars selected in this unusual manner will improve our understanding of the physics behind this extremely variable and diverse class of AGN. The object positions, variability statistics, and color information are available using the Palomar-QUEST CasJobs server. The time domain is just beginning to be explored over large sky areas; we do not know exactly what a violently variable sample will hold. About 20% of the sample has been classified in the literature; over 70% of those objects are known or likely AGN. The remainder largely consists of a variety of variable stars, including a number of RR Lyrae and cataclysmic variables.

2025, IEEE Photonics Technology Letters

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2025, IEEE Photonics Technology Letters

2025

2025, UV/EUV and Visible Space Instrumentation for Astronomy II

The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.

2025, IEEE Photonics Technology Letters

A microwave photonic system that simultaneously implements multiple parallel instantaneous frequency measurement systems within a single highly nonlinear optical fiber is proposed and practically demonstrated. Three optical carriers of different wavelengths are modulated by the same radio-frequency (RF) signal and then delayed differentially. All three carriers are then mixed within a highly nonlinear optical fiber. The mixing products are separated, and the optical power of each is used to deduce input RF frequency. We demonstrate simultaneous acquisition of two distinct frequency measurement responses over the range from 1 to 40 GHz. This system is all-optical and requires no high-speed electronic components. Avenues for further increasing the number of simultaneous channels are identified.

2025, Czechoslovak Journal of Physics

Multilayer thin-film structures have been used to model and analyze the performance of broad-band-pass interference optical filters in visible spectrum. Starting from nine-layer configuration comprising quarter-wave layers, the number of layers is increased to make the pass band smooth with steep slopes and square band-pass characteristics. The layer materials are also varied to improve the performance of the filters. Further, matching layers are also introduced with incident medium and the substrate to reduce the magnitude of ripples in the pass band. Shift in the peak wavelength is also investigated as a function of angle of incidence.

2025

Exploration of advanced modulation formats and multiplexing techniques for next generation optical access networks are of interest as promising solutions for delivering multiple services to end-users. This thesis addresses this from two different angles: high dimensionality carrierless amplitudephase (CAP) and multiple-input multiple-output (MIMO) radio-over-fiber (RoF) systems. High dimensionality CAP modulation has been investigated in optical fiber systems. In this project we conducted the first experimental demonstration of 3 and 4 dimensional CAP with bit rates up to 10 Gb/s. These results indicate the potentiality of supporting multiple users with converged services. At the same time, orthogonal division multiple access (ODMA) systems for multiple possible dimensions of CAP modulation has been demonstrated for user and service allocation in wavelength division multiplexing (WDM) optical access network. 2 × 2 MIMO RoF employing orthogonal frequency division multiplexing (OFDM) with 5.6 GHz RoF signaling over all-vertical cavity surface emitting lasers (VCSEL) WDM passive optical networks (PONs). We have employed polarization division multiplexing (PDM) to further increase the capacity per wavelength of the femto-cell network. Bit rate up to 1.59 Gbps with fiber-wireless transmission over 1 m air distance is demonstrated. The results presented in this thesis demonstrate the feasibility of high dimensionality CAP in increasing the number of dimensions and their potentially to be utilized for multiple service allocation to different users. MIMO multiplexing techniques with OFDM provides the scalability in increasing spectral efficiency and bit rates for RoF systems. High dimensional CAP and MIMO multiplexing techniques are two promising solutions for supporting wired and hybrid wired-wireless access networks. i First of all, I would like to attribute my sincere gratitude to my supervisor and co-supervisor, Professor Idelfonso Tafur Monroy and Assistant Professor Jesper Bevensee Jensen for their encouragement, support and enthusiasm. They always spent time with me and guided me through the problems that I have encountered. It is a privilege to work with them. Thanks a lot from my heart. I am very grateful to the Ministry of Higher Education of Malaysia (MOHE) and University of Tun Hussein Onn Malaysia (UTHM) for providing me with a scholarship. I would not have completed a Ph.D without this financial assistance. My warmest thanks are extended to my closest friend Lei, Xu, Xiaodan, and Ying. We have spent time together in the lab doing the experiment with a very good team working spirit. My sincere thanks to Kamau and Xianbin for their practical assistance. I would also like to thank all my colleagues at Metro-Access group, Darko, JJ, Neil, Alexey, Thang, Valeria, Roberto, Robert, Silvia, Alexander, Bomin, Miguel, David and also my colleagues in DTU Fotonik. I must also thank Evarist my ex-officemate in building 343 DTU Fotonik for sharing all the good food recipes. I want to thank to all my Malaysian friends in Denmark for friendship through all these years. Many thanks for supporting each other, and I really hope this friendship will last forever. The last, and foremost, I would like to thank my parents, mother in law, my brothers, my husband, Shamsudin Bin Awang and my two handsome heroes: Muhammad Hazlam and Muhammad Hulaif. Thanks for their 'dua', love, patience, and encouragement. This made my Ph.D study possible and joyful at DTU Fotonik.

2025, PICS

In acquiring digital images, electronic systems not only detect optical signals but also convert them into a digital form for further image processing and exchange. Practical systems can introduce error during color calibration, and when acquiring image scene information. For large populations it is often assumed that the error can be modeled as a random variable having a zero mean. In the case of a single color instrument, camera or scanner, however, error due to deterioration of a physical standard, optical filter or detector will introduce a bias into the measurement or image data. This error is modified as the signals are transformed (processed) into their final form. An error-propagation method is shown to describe the influence of the dataprocessing path on the magnitude of bias error. This approach is related to the propagation of image noise, or variance. The analysis is applied in examples drawn from color-measurement and digital image processing.

2025

2025, Bulletin of the American Physical Society

Submitted for the DFD13 Meeting of The American Physical Society Hydraulic jumps and contact lines formed by jet impact on an incline LAURENT LIMAT, ALEXIS DUCHESNE, REMY HERBAUT, LUC LEBON, Matiere et Systemes Complexes (MSC), UMR 7057 of CNRS and Univ. Paris Diderot, Paris, France — We have investigated the shape and stability of hydraulic jumps formed on an inclined plate, around a jet under normal impingement. We have explored three different wetting conditions: total wetting, partial wetting and super-hydrophobicity. In the first case, a strong departure to axisymmetry of the shape is observed, with often disappearance of the lower part of the jump. One also observes the formation of an effective, curved, static contact line around the jump, with a similar horse-shoe structure. Surprisingly, the effective jump radii defined in the directions normal and parallel to the in plane gravity follow quite well Bohr et al scaling, initially proposed for a horizontal, axisymetric jump, b...

2025, ecio-conference.org

The continuous improvement of microtechnologies and the recent and very fast development of nanotechnologies have drastically modified technical and economical landscapes in many fields of activities. It's particularly true in optics because of the special position of the visible and near infrared optical wavelengths at the border of the micrometric and the nanometric world. Integrated optics which is now almost 30 years old is one of the more relevant fields to illustrate this double impact. This presentation will try to summarise the long and attractive way followed since the end of the 60's by one of the more fruitful branch of optics and to foresee some of its future developments.

2025, IEEE Photonics Journal

We propose and experimentally demonstrate that, contrary to what was thought up to now, an efficient BB84 operation is feasible using the double phase modulator (PM-PM) configuration in frequency-coded quantum key distribution systems without dispersion compensation. This is achieved by exploiting the chromatic dispersion provided by the fiber linking Alice and Bob. Thus, we refer to this system as dispersion supported or as the DS BB84 PM-PM configuration.

2025

Several experiments, related to controlled thermonuclear fusion research and highly relevant for large size tokamaks including ITER, have been carried out in ADITYA, an ohmically heated circular limiter tokamak. Repeatable plasma discharges of maximum plasma current of ~ 160 kA and discharge duration beyond ~ 250 ms with plasma current flattop duration of ~ 140 ms has been obtained for the first time in ADITYA. The discharge reproducibility has been improved considerably with Lithium wall conditioning and improved plasma discharges are obtained by precisely controlling the plasma position. In these discharges, chord-averaged electron density ~ 3.0 – 4.0 x 10^19 m^-3 using multiple hydrogen gas puffs, electron temperature of the order of ~ 500 700 eV have been achieved. Novel experiments related to disruption control are carried out and disruptions, induced by hydrogen gas puffing are successfully mitigated using biased electrode and ICR pulse techniques. Runaway electrons are succes...

2025, 2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference

Broadband variable chromatic dispersion in C-band frequency range is demonstrated using novel nanostructured electro-optic waveguide consisting of low-loss Si 3 N 4 rectangular core and Si/SiO 2 two-dimensional photonic-crystal layer... more

2025

Message-signal filtering in optical chaos communications using injection-locked laser diodes (LDs) are theoretically studied In the driven response of injection-locked LDs, the driving force is supplied to drive field and carrier with energy transfer. The driving-energy transfer occurs for sinusoidal signals masked by chaos, resulting in message signal filtering in the chaos communications.

2025, Current Medical Imaging Reviews

2025, International journal of engineering research and technology

This paper presents a novel, integrated a photonic antenna with a power control scheme. The controller regulates the levels of radiated power by adjusting the bising voltage of a side-illuminated waveguide photo detector (WGPD). The WGPD converts the RF-modulated optical power into a microwave signal, which is then fed to an antenna The controller uses as input the noise level measurements of a different receiving antenna, and periodically calculates the necessary amount of power that must be radiated. The performance of the RF/photonic device has been studied theoretically and experimentally. The addition of power control capabilities, the device realizes an early attempt to design -smart‖ photonic antennas.

2025

While many Japanese companies have made the high quality products recently, they have worried about keeping their brand value. In contrast to such Japanese companies, many luxury brand companies have kept and developed their high brand value in Japanese and global markets. This thesis reveals the way of the brand innovation management that helps keeping and developing the luxury brands' value through the case of the luxury brand "GUCCI." It shows that the luxury brand companies have to manage the sustaining innovation and disruptive innovation to keep and develop their brand value. It also shows that the matured craftsmanship and the system to manage two simultaneous innovations are important.

2025

I propose a method of parallax (a.k.a. binocular disparity) estimation from stereo image without any cue using Rotation Invariant Phase Only Correlation (RIPOC). In general, to estimate parallax of regular stereo image pair, whole image calculates RIPOC. On the other hand, to estimate parallax of Single Image Random Dot Stereogram (RDS), RIPOC applies a part of image and sliding window matching. Using the estimated parallax, stereo disparity calculation, RDS to stereo pair conversion and Anaglyph 3D creation are tested to confirm its usefulness.

2025, Optics Communications

A general method based on the predistortion technique is presented for determining the optimum coupling parameters of multiplecoupled microring filters in the presence of known uniform resonator loss. The technique involves predistorting the filter transfer function by shifting its poles and zeros to compensate for loss in the microring resonators due to material absorption, surface roughness scattering, coupling loss and bending loss. It is shown that by sacrificing some in-band insertion loss, both the amplitude and group delay responses of the filter can be recovered when loss is present. Application of the method to synthesizing lossy microring filters in both the digital z-domain and analog s-domain will be presented. The proposed technique is general in that it can be applied to both amplitude and phase filters constructed of coupled microresonators in the most general two-dimensional coupling topology.

2025

4,760,351 7/1988 Newell et al. ......................... 331/48 5,023,624 * 6/1991 Heckman et al. ... ... 343/860 5,140,110 * 8/1992 Nakagawa et al. ....... ... 174/250 5,276,455 1/1994 Fitzsimmons et al. .............. 343/777 5,376,942 * 12/1994 Shiga .................... 343/700 MS 5,381,157 * 1/1995 Shiga ............................ 343/700 MS 5,450,090 * 9/1995 Gels et al. ... 343/700 MS 5,488,380 * 1/1996 Harvey et al. ....................... 343/368 5,608,263 * 3/1997 Drayton et al. ...................... 257/728

2025, Proceedings of the 8th WSEAS …

Microwave sensors are robust non-contact measurement devices for industrial and vehicular application. Phased array-antenna modules, located in the front-end of the sensor, are often used to enhance the performance of this device. In this paper, a novel 24-GHz microstrip linear array antenna with beam-scanning and signal-amplification properties are presented. The phase shift section is designed using digital and analogue phase control properties, to minimize the requirement of complicated control circuits and large external biasing magnet .

2025

We have flattened the gain spectrum of a commercial Erbium-doped fibre amplifier, obtaining a curve with approximately 3 dB of ripple, from 1524 nm to 1551 nm, using long-period fibre gratings as equalising optical filters. The... more

2025, TDX (Tesis Doctorals en Xarxa)

The dynamic behavior of the traffic demand, due to the advent of technologies such as cloud services or Internet of Things, is increasing. In fact, heterogeneous connections with different characteristics such as bandwidth or bit rate are expected that coexist in the optical networks. An evolution of the optical networks is crucial to face the new claims. In this respect, Elastic Optical Networks (EONs) emerge as a cost-effective, flexible and dynamic solution. The main idea is the efficient utilization of the optical spectrum by combining flexible transceivers, flexi-grid and flexible optical switching. Including the principles of Software Defined Network (SDN) paradigm further flexibility and adaptability can be achieved. The adoption of the SDN architecture involves the separation of the control plane and data plane enabling the programmability of the network in a dynamic way. First of all, I would like to express my gratitude to my advisors Josep M. Fàbrega and Michela Svaluto Moreolo and my tutor Gabriel Junyent for giving me the opportunity to work at CTTC and develop my thesis at UPC. I would particularly like to thank my advisors Josep M. Fàbrega and Michela Svaluto Moreolo for their guidance, comments and suggestions to the successful development of this thesis. In addition, I would like to extend my gratitude to Laia Nadal for her support and advice. My sincere thanks also to Nicola Calabretta, Chigo Okonkwo, Sjoerd van der Heide, X. (Xuwei) Xue, John van Weerdenburg, who gave me the opportunity to join their team during my research stay at TU/e (Netherlands). Further, I would like to extend my gratitude to Dr. Albert Rafel, Prof. Alberto Gatto for reviewing this thesis. Also, I would like to thank Dr. Albert Rafel, Prof. Alberto Gatto and Prof. Salvatore Spadaro for agreeing to serve in this thesis' committee. My gratitude also extends to Dr. Ana González and Jaume Comellas, for fulfilling the role of substitute members of the committee. I am deeply grateful to all the people from CTTC both at a professional and a personal level. In particular, I would like to express my sincere gratitude to my friends and collegues Laia Nadal, Maria Gregori, Jessica Moysen, Miguel Ángel Vázquez, Miquel Calvo, Luis Carlos Buelga and Jesús Soriano. I would also like to thank the rest of my friends who have always been by my side during this period. I thank you very much for having given me all the support, collaboration, encouragement and especially affection and friendship. Por último, pero no menos importante, me gustaría agradecer a mi familia por todo su apoyo incondicional en el desarollo de la tesis y en mi vida en general.

2025, Majlesi Journal of Telecommunication Devices

The structure of an optical communication system similar to any other electrical connection system consists of several elements, including the transmitter (light source), medium (fiber optic) and receiver (optical detector) is. Standard single-mode fibers for data transmission at wavelengths normally used 33/1 micrometers and 55.1 micrometers. Optical fibers in the wavelength range of the losses are insignificant. Despite the low loss optical fibers for data transmission over long distances (more than 50 km), the need to strengthen our optical pulses again. Therefore, the optical amplifiers are required. Semiconductor optical amplifier polarization is sensitive to the structure used to relieve tension. The advantages of optical communication devices compared to other communication devices, such as bandwidth, low weight, low-loss optical fiber, flexibility, safety data sent against electromagnetic interference and inexpensive noted.

2025, International Topical Meeting on Microwave Photonics MWP 2000 (Cat. No.00EX430)

A novel modulation scheme to simultaneously transmit broadband signal at both baseband and millimetre-wave RF carriers over optical fibre links is proposed and demonstrated. The key parameters of this technique are optimised for achieving... more

2025, Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013

We propose and experimentally demonstrate an optical wireless DWDM system at 60 GHz with optical incoherent heterodyne up-conversion using an optical frequency comb. Multiple users with wireline and wireless services are simultaneously... more

2025, Applied Surface Science

Ablation experiments employing Ti:sapphire laser pulses with durations from 30 to 340 fs (centre wavelength 800 nm, repetition rate 1 kHz) were performed in air. Absorbing ®lters (Schott BG18 and BG36) served as targets. The direct focusing technique was used under single-and multi-pulse irradiation conditions. Ablation threshold ¯uences were determined from a semi-logarithmic plot of the ablation crater diameter versus laser ¯uence. The threshold ¯uence decreases for a shorter pulse duration and an increasing number of pulses. The multi-pulse ablation threshold ¯uences are similar to those of undoped glass material ($1 J cm À2 ). That means that the multi-pulse ablation threshold is independent on the doping level of the ®lters. For more than 100 pulses per spot and all pulse durations applied, the threshold ¯uence is practically constant. This leads to technically relevant ablation threshold values.

2025, IEICE Transactions on Electronics C

The author developed a GaAs wideband IQ modulator IC, which is utilized in RF signal source instruments with direct-conversion architecture. The layout is fully symmetric to obtain a temperature-stable operation. However, the actual temperature drift of EVM (Error Vector Magnitude) is greater in some frequency and temperature ranges than the first generation IC of the same architecture. For applications requiring the precision of electric instrumentation, temperature drift is highly critical. This paper clarifies that linear phase error is the dominant factor causing the temperature drift. It also identifies that such temperature drift of linear phase error is due to equivalent series impedance, especially parasitic capacitance of the phase shifter. This effect is verified by comparing the SSB measurements to a mathematical simulation using an empirical temperature-dependent small-signal FET model.

2025

Accurate attitude determination is an important enabler for micro-and nanosatellite missions. For remote sensing applications and formation flying missions, the attitude of the spacecraft must be known and controlled with a high accuracy. ISIS introduces a modular and scalable attitude determination system based on a multi-aperture miniature star sensor. Based on a patented concept, the Multi-Aperture Baffled Starsensor, the attitude sensor integrates several apertures into a single star tracker. The main advantage of this concept is that it eliminates the need for large baffles as there is a redundancy of independent apertures. Even when several apertures are obstructed, for instance by the Earth and the Sun simultaneously, the star tracker will still have apertures available with a 'free' field of view and will be able to determine star positions. The concept consists of a standalone sensor element for an attitude determination and control system and allows for integration, alignment, and calibration of the sensor on subsystem level rather than on spacecraft level. The system consists of an optical head that can include up to 9 miniature star cameras, and an electronics system that combines the star camera inputs and determines and outputs the spacecraft attitude vector.