المؤلفون: Qinggui Tan, Xiaojun Li, Shanghong Zhao, Dong Liang, Yongsheng Gao, Wei Jiang

المصدر: Optics Communications. 445:41-49

مصطلحات موضوعية: Physics, Spurious-free dynamic range, business.industry, Local oscillator, Bandwidth (signal processing), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, 010309 optics, Optics, Intermediate frequency, 0103 physical sciences, Electronic engineering, Radio frequency, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Wideband, Center frequency, 0210 nano-technology, business, Passband

الوصف: A wideband photonic microwave channelization and image-reject down-conversion system is proposed and experimentally demonstrated. The broadband radio frequency (RF) and electrical local oscillator (LO) signals are applied to Mach–Zehnder modulators (MZMs) and be multiplexed for channelized reference. By employing DPMZMs, different optical frequency shifting LO signals for channelization are generated. Due to the frequency difference between the modulated RF signals and frequency shifted LO signals, multichannel intermediate frequency (IF) signals can be easily separated by the followed photonic I/Q receiver. Experimental results show that the RF signal with a bandwidth of 3 GHz could be down-converted into six IF signals with the same center frequency of 750 MHz and the same bandwidth of 500 MHz. The measured spurious free dynamic range (SFDR) is 101 dB•Hz 2∕3 , the passband fluctuation is less than 0.5 dB; the channel isolation is over 22 dB, and the image-rejection is over 22 dB. A QPSK vector signals with 50 Msym/s and 16.5–19.5 GHz operating frequency is successfully demonstrated using the proposed scheme, and good EVMs and constellation diagrams are obtained. The proposed photonic channelization and image-reject down-conversion system may have potential applications in the RF frontends of future systems such as broadband integrated satellite communication and multi-service wireless networks.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::fc273e3e0c870b5c2834aa0850af3b23Test
https://doi.org/10.1016/j.optcom.2019.04.013Test

المؤلفون: Ji Xu, Yunqing Lu, Chen Yilin, Jin Wang, Lu Xinyi, Baifu Zhang, Liu Ning

المصدر: Optics Communications. 444:39-44

مصطلحات موضوعية: Admittance, Materials science, business.industry, Transfer-matrix method (optics), Surface plasmon, Physics::Optics, 02 engineering and technology, Dielectric, Integrated circuit, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, 010309 optics, Optics, Fiber Bragg grating, Transmission (telecommunications), law, 0103 physical sciences, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 0210 nano-technology, business, Passband

الوصف: Hybrid plasmonic waveguide Bragg gratings (HPWBGs) are promising and essential components in ultracompact integrated circuits. In this paper, the transmission spectra of HPWBGs composed of two types of HPWs with different low-index dielectric layers are calculated through the transfer matrix method. Admittance match theory is used to analyze and improve transmission properties. Two admittance-matching conditions (the complete matching and the conjugate matching) are illustrated to optimize the transmission spectra effectively in specific passband, and the properties of bandgaps are also influenced. The results demonstrate the feasibility of the admittance match theory in modulating the transmission spectra of HPWBGs and this work provide a design approach for HPWBGs with a small footprint.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::b686593fa369b89641a2064fcb6e919dTest
https://doi.org/10.1016/j.optcom.2019.03.054Test

المؤلفون: Zanyun Zhang, He Li, Yanming Li, Zan Zhang, Beiju Huang, Yaxin Yu, Chuantong Cheng, Tianxi Gao, Hongda Chen

المصدر: Optics Communications. 437:168-173

مصطلحات موضوعية: Silicon photonics, Materials science, Demultiplexer, business.industry, Bandwidth (signal processing), 02 engineering and technology, Stopband, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, 010309 optics, Resonator, Optics, Wavelength-division multiplexing, 0103 physical sciences, Channel spacing, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 0210 nano-technology, business, Passband

الوصف: A monolithically integrated multi-channel receiver fabricated on the Silicon-on-Insulator (SOI) platform is demonstrated experimentally. This receiver is composed of an eight-channel thermally tunable microring resonator (MRR) filter as the wavelength division multiplexing (WDM) demultiplexer and an array of high speed waveguide-integrated Ge-on-Si photodetectors (PDs) for light detection. Second-order MRRs were utilized in each channel to obtain steeper roll-off from passband to stopband and lower crosstalk. The receiver was fabricated by using CMOS-compatible fabrication process at IME A*STAR. With the thermal tunability, the channel spacing can be adjusted according to different channel grid. Lower than −30 dB crosstalk and higher than 50 GHz 3-dB bandwidth was obtained for the demultiplexer with a channel spacing of 150 GHz. Proof-of-principle demonstration shows that each channel is capable of operating at a data rate of 10 Gb/s, resulting in an aggregate data rate of 80 Gb/s.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::19cec870527693b087e95d8a1a182971Test
https://doi.org/10.1016/j.optcom.2018.12.067Test

المؤلفون: Mohsen Hayati, Shiva Khani

المصدر: Optics Communications. 505:127534

مصطلحات موضوعية: Coupling, Materials science, business.industry, Surface plasmon, Optical communication, Single-mode optical fiber, Finite-difference time-domain method, Stopband, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Optics, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, business, Passband, Plasmon

الوصف: Three novel refractive index (RI) sensors based on one, two, and three H-shaped cavities (HCs) and metal–insulator–metal (MIM) waveguides are proposed in this paper. By coupling more than one HC (two and three), the Q-factor and then the FOM value of the designed RI sensors increase. A well-known method for increasing the sharpness transition between the passband and stopband of a spectrum is coupling cavities together. Fortunately, the proposed HC has such a property that increases the FOM value. The maximum obtained FOM of the proposed sensors using one, two, and three HCs reached 69.5, 100.19, and 108.36 RIU-1, respectively. Three proposed plasmonic structures which are used to design RI sensors have single-mode spectra in a wide wavelength range of 500 to 2000 nm. A single-mode spectrum is easier to cope with in circuits with higher complexity such as RI sensors. The metal and insulator materials that are used in the designed structures are silver and air, respectively. The finite-difference time-domain (FDTD) method is used for the numerical investigation of the proposed RI sensors. To verify FDTD simulations, the basic rectangular cavity which is used to design HC is analyzed using an analytical method. In summary, the benefits of the proposed RI sensors are having single-mode spectra in a wide wavelength range and also their simple structures. The proposed topology easily be redesigned and adapted with different numbers of HCs without disturbing its single-mode spectrum to achieve various FOM values. Furthermore, considering the fact that the proposed cavity is based on rectangular shapes, it has a simple fabrication process. Taking into account the mentioned advantages of the proposed structures, they can be used in integrated optical circuits for optical communication purposes.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::a40b43b3fa2ba3a96e478b0bdda4cd6cTest
https://doi.org/10.1016/j.optcom.2021.127534Test

المؤلفون: Tingge Dai, Li Shiqi, Bohao Zhang, Yuehai Wang, Weiwei Chen, Jie Zhang, Qiang Fu, Pengjun Wang, Jianyi Yang

المصدر: Optics Communications. 426:206-211

مصطلحات موضوعية: Materials science, Silicon, Physics::Optics, chemistry.chemical_element, 02 engineering and technology, Spectral line, law.invention, symbols.namesake, Resonator, 020210 optoelectronics & photonics, Optics, law, 0202 electrical engineering, electronic engineering, information engineering, Passband filter, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Extinction ratio, business.industry, Graphene, Fermi level, Bandwidth (signal processing), Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, chemistry, symbols, business

الوصف: A bandwidth-tunable optical passband filter based on graphene–silicon waveguide is proposed. The device is designed by utilizing a structure with four triple series-coupled microring resonators. By changing the Fermi level of graphene to lead to the variation of the modal effective index, the transmission spectra of triple series-coupled microring resonators can be coherently combined to provide the adjustable bandwidth as desired. A detailed analysis of the designed device is presented. Numerical simulations show that the effective bandwidth tuning range from 2.70 to 6.30 nm can be obtained when each microring resonator is independently controlled. With the maximum bandwidth tunability, the designed tunable filter has a minimum extinction ratio larger than 92.35 dB.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::cca6526d82a865fc37f62d1eae3ac96dTest
https://doi.org/10.1016/j.optcom.2018.05.049Test

المؤلفون: A. Sauceda-Carvajal, Cristina M. Gómez-Sarabia, Luis M. Ledesma-Carrillo, Jorge Ojeda-Castaneda

المصدر: Optics Communications. 498:127228

مصطلحات موضوعية: Carrier signal, Computer science, business.industry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Highly selective, 01 natural sciences, Transfer function, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, 010309 optics, Matrix (mathematics), Optics, 0103 physical sciences, Barker code, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 0210 nano-technology, business, Passband, Throughput (business), Algorithm, Direct product

الوصف: We disclose the use of the Barker sequences for generating, with phase-only masks, highly selective windows in the optical transfer functions (OTF). The proposed passband procedure is extended to 2-D, by defining a Barker matrix as the direct product of Barker sequence. We explore the use of several configurations, and we recognize as a good choice the use of a pair of adjacent, non-overlapping, Barker masks. Our proposal is applied for identifying envelopes in carrier frequency photographs.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::b8499e63c60431672bf0cf8df3b749f2Test
https://doi.org/10.1016/j.optcom.2021.127228Test

المؤلفون: Su-Hyun Park, Xiaoping Wu, Tae-Hyun Park, Min-Cheol Oh, Jun-Kyu Seo

المصدر: Optics Communications. 416:185-189

مصطلحات موضوعية: Materials science, Optical fiber, Birefringence, business.industry, Circulator, Physics::Optics, 02 engineering and technology, Distributed Bragg reflector, Polarization (waves), 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Small form factor, 010309 optics, Wavelength, 020210 optoelectronics & photonics, Optics, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, business, Passband

الوصف: In order to simplify the receiver configuration in a wavelength division multiplexed optical fiber network, compact wavelength tunable filters have long been expected to be used as channel selectors. Bragg reflector inherently has the most suitable reflection spectrum for filtering a single wavelength from the densely multiplexed wavelength signal. Polymer has high thermo-optic coefficient and good thermal insulation property compared to the other optical waveguide materials such as silicon and silica materials. This can be used to broadly tune the reflection spectrum of Bragg reflector using a simple micro-heater. In this work, a micro-optic circulator component and a polymeric Bragg reflector device are assembled to produce a small form factor tunable receiver. Compared to the integrated-optical versions, the micro-optics are based on well-developed manufacturing processes and can achieve competitive production yields. The device exhibits high reflectivity with a flat top passband, and a polarization dependence of 0.06 nm achieved by virtue of the low birefringence of LFR polymer, which make a significant contribution to the implementation of polarization independent tunable receiver. The wavelength tuning range of 40 nm is demonstrated by using a bottom located heater with a groove for heat isolation.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::e62a8840bf6e762b87181f1f67008759Test
https://doi.org/10.1016/j.optcom.2018.02.018Test

المؤلفون: Wei Li, Ming Li, Ninghua Zhu, Tengfei Hao, Shi Nuannuan

المصدر: Optics Communications. 407:27-32

مصطلحات موضوعية: Materials science, business.industry, Bandwidth (signal processing), 020206 networking & telecommunications, 02 engineering and technology, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, 020210 optoelectronics & photonics, Optics, Band-pass filter, Fiber Bragg grating, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Center frequency, Photonics, business, Phase modulation, Passband, Free spectral range

الوصف: We propose a photonic scheme to realize a reconfigurable microwave photonic filter (MPF) with flexible tunability using a multi-wavelength laser (MWL) and a multi-channel phase-shifted fiber Bragg grating (PS-FBG). The proposed MPF is capable of performing reconfigurability including single bandpass filter, two independently bandpass filter and a flat-top bandpass filter. The performance such as the central frequency and the bandwidth of passband is tuned by controlling the wavelengths of the MWL. In the MPF, The light waves from a MWL are sent to a phase modulator (PM) to generate the phase-modulated optical signals. By applying a multi-channel PS-FBG, which has a series of narrow notches in the reflection spectrum with the free spectral range (FSR) of 0.8 nm, the +1 st sidebands are removed in the notches and the phased-modulated signals are converted to the intensity-modulated signals without beating signals generation between each two optical carriers. The proposed MPF is also experimentally verified. The 3-dB bandwidth of the MPF is broadened from 35 MHz to 135 MHz and the magnitude deviation of the top from the MPF is less than 0.2 dB within the frequency tunable range from 1 GHz to 5 GHz.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::911ed34288e39303f80f1d4720503ce9Test
https://doi.org/10.1016/j.optcom.2017.08.073Test

المؤلفون: Wei Chen, Ya Jin, Ninghua Zhu, Yinfang Chen

المصدر: Optics Communications. 491:126961

مصطلحات موضوعية: Physics, business.industry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Signal, Thresholding, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Power (physics), 010309 optics, Wavelength, Optics, Filter (video), 0103 physical sciences, Waveform, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 0210 nano-technology, business, Focus (optics), Passband

الوصف: In this paper, we investigate and experimentally demonstrate the filter parameters’ effect on the performance of the typical all-optical thresholding (AOT) system. By establishing a conceptual scheme, the AOT’s output power, waveform, power transform function, as well as the bit-error-rate performance are measured and analyzed with different filter parameters including center wavelength and passband width, while available researches mainly focus on employing various fibers. We typically select the center wavelength of 1567, 1576, 1585, 1594, 1603 nm, and each center wavelength corresponds to the passband width of 3, 6, 9, 12, 15, 18 nm, respectively. And when we fix the signal power injected into the highly nonlinear fiber (HNLF) to 18.5 dBm, an optimal system performance with power improvement of 4 dB can be achieved for a center wavelength of 1576 nm and a corresponding passband width of 18 nm. This result provides a new perspective for future studies on thresholding performance optimization.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::25f3df15d05cc60a512bb8c34f881428Test
https://doi.org/10.1016/j.optcom.2021.126961Test

المؤلفون: Honghui Zhu, Xiao-Zhi Wang, Zhigang Liu

المصدر: Optics Communications. 395:236-240

مصطلحات موضوعية: Materials science, business.industry, Air interface, Impedance matching, Physics::Optics, Metamaterial, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Photonic metamaterial, Optics, Filter (video), 0103 physical sciences, Dispersion (optics), Electrical and Electronic Engineering, Physical and Theoretical Chemistry, 010306 general physics, 0210 nano-technology, business, Passband, Localized surface plasmon

الوصف: We present a theoretical and numerical study of a compound structure optical metamaterials filter in 14.8-19.8 THz region. Effects of variations in thickness of dielectric layer H and structural parameters on the pass-band are surveyed. Simulated results indicate that the sidewall length of the main air hole and the nano-hole mainly define the impedance matching condition. The pass-band can be expanded due to impedance matching condition between the designed structure and air interface is achieved through optimizing the dimensional parameters of the designed structure. Meanwhile, the pass-band can be also expanded by reducing the thickness of dielectric layer.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::eb80bf32f334c7d0c04219c2884ac803Test
https://doi.org/10.1016/j.optcom.2016.06.055Test