Showing papers by "Xinliang Zhang published in 2011"
TL;DR: A novel and simple bandwidth and wavelength-tunable optical bandpass filter based on silicon microrings in a Mach-Zehnder interferometer (MZI) structure is proposed and demonstrated.
Abstract: A novel and simple bandwidth and wavelength-tunable optical bandpass filter based on silicon microrings in a Mach-Zehnder interferometer (MZI) structure is proposed and demonstrated. In this filter design, the drop transmissions of two microring resonators are combined to provide the desired tunability. A detailed analysis and the design of the device are presented. The shape factor and extinction ratio of the filter are optimized by thermally controlling the phase difference between the two arms of the MZI. Simultaneous bandwidth and wavelength tunability with in-band ripple control is demonstrated by thermally tuning the resonance offset between the two microring resonators.
109 citations
TL;DR: In this article, a two-tap tunable photonic filter with one complex coefficient is presented. But the phase of the RF signal can be tuned continuously by simply controlling the optical power through changing variable optical attenuators.
Abstract: A tunable microwave photonic filter with complex coefficients is presented. The complex coefficient is generated using an all-optical radio-frequency (RF) phase shifter, which contains an optical differentiator to realize phase modulation to intensity modulation conversion. The phase of the RF signal can be tuned continuously by simply controlling the optical power through changing variable optical attenuators. A two-tap tunable filter with one complex coefficient is experimentally demonstrated and a continuous tuning range of a half free spectral range is realized without changing the shape of the frequency response.
38 citations
TL;DR: In this article, the authors comprehensively analyze the demodulation of WDM non return-to-zero differential phase-shift keying (NRZ-DPSK) signals by a single microring resonator.
Abstract: We comprehensively analyze the demodulation of wavelength division multiplexed (WDM) non return-to-zero differential phase-shift keying (NRZ-DPSK) signals by a single microring resonator. Simultaneous demodulation of multiple 40 Gbit/s WDM NRZ-DPSK channels is demonstrated using a single silicon microring resonator with free spectral range (FSR) of 100 GHz. Bit error measurements show very good performance for both through and drop port demodulations for all channels, and the drop port demodulation exhibits better wavelength detuning tolerance than for demodulation using a Mach-Zehnder delay interferometer (MZDI).
37 citations
TL;DR: In this article, a switchable single-longitudinalmode (SLM) dual-wavelength fiber laser incorporating a reconfigurable dual-pass Mach-Zehnder interferometer (MZI) filter was proposed and demonstrated, which can be applied in microwave generation.
35 citations
TL;DR: In this paper, a simple approach to generating ultra wideband (UWB) pulses with a single optical carrier is proposed and demonstrated using a single laser diode (LD) and two cascaded Mach-Zehnder modulators (MZMs).
Abstract: A simple approach to generating ultra-wideband (UWB) pulses with a single optical carrier is proposed and demonstrated. The approach is realized by using a single laser diode (LD) and two cascaded Mach-Zehnder modulators (MZMs). In the experiment, the two MZMs are biased at opposite slopes of their modulation curves respectively and the time delay between them is variable. Negative monocycle pulses with a center frequency of 4.3 GHz and a fractional bandwidth of 165%, and positive monocycle pulses with a center frequency of 4.3 GHz and a fractional bandwidth of 188% are generated, respectively. The feasibility of high order UWB pulses generation with a single optical carrier is also discussed.
30 citations
TL;DR: In this paper, a microwave photonic filter with a single passband between 0 and 40 GHz was proposed and experimentally demonstrated using an electro-optic phase modulator (EOPM) and a Fabry-Perot semiconductor optical amplifier.
Abstract: We propose and experimentally demonstrate a microwave photonic filter based on an electro-optic phase modulator (EOPM) and a Fabry-Perot semiconductor optical amplifier (FP-SOA). A microwave photonic filter with a single passband between 0 and 40 GHz is obtained. In the single passband microwave photonic filter, the microwave subtraction effect is introduced in optical domain to improve the performance. A theoretical model is established to describe the operation principle of the microwave photonic filter, and the predicted results show good agreement with the experimental results. In the experiment, the center frequency and the 3-dB bandwidth are 18.3 GHz and 99.5 MHz, respectively, with the corresponding Q factor of 184, and the rejection ratio and shape factor are 34.3 dB and 5, respectively. The continuous wideband tunability of the microwave photonic filter is also demonstrated by adjusting the bias current of FP-SOA.
28 citations
TL;DR: In this paper, an optimized quantum-well (QW)-semiconductor optical amplifier (SOA) was proposed for regenerating phase-modulated signals, such as return-to-zero differential-phase-shift keying (RZ-DPSK) signal.
Abstract: In this paper, we present an optimized quantum-well (QW)-semiconductor optical amplifier (SOA) which is capable of regenerating phase-modulated signals, such as return-to-zero differential-phase-shift keying (RZ-DPSK) signal. Based on the optimized QW SOA, the amplitude fluctuations are suppressed while the phase information is preserved. The essential mechanism of the optimized QW SOA is the low linewidth enhancement factor (α-factor), which can be obtained by means of structural optimization. Based on the numerical model, the power fluctuations can be suppressed from 4.26 mW (33% of input peak power) to 1.59 mW (13% of output peak power) at 40 Gb/s. The average phase noise induced by SOA is as small as 50. Furthermore, the DPSK signal regeneration scheme based on a single QW SOA is quite simple and stable.
25 citations
TL;DR: An all-optical demodulation and format conversion scheme for multi-channel (carrier suppressed) return-to-zero differential phase shift keying ((CS)RZ-DPSK) signals by utilizing a single delay interferometer with half bit delay is proposed.
Abstract: We proposed and demonstrate an all-optical demodulation and format conversion scheme for multi-channel (carrier suppressed) return-to-zero differential phase shift keying ((CS)RZ-DPSK) signals. By utilizing a single delay interferometer (DI) with half bit delay, multi-channel (CS)RZ-DPSK signals can be demodulated simultaneously at the destructive port of the DI, with the corresponding converted nonreturn-to-zero differential phase shift keying (NRZ-DPSK) signals obtained at the constructive port. The proposed multi-channel operation has been demonstrated for 6*20 Gb/s RZ-DPSK and 6*40 Gb/s CSRZ-DPSK signals, with ~0.8 and 1.2 dB average power penalties for the format conversions respectively.
22 citations
TL;DR: A dual-band optical filter based on a single microdisk resonator based on the transfer matrix method and two low-order resonant modes can be effectively triggered by optimizing the waveguide width and spacing gap between the compact resonator and waveguides.
Abstract: We propose and experimentally demonstrate a dual-band optical filter based on a single microdisk resonator. An analytical model is built based on the transfer matrix method and is applied to simulate the properties of such a device. Competition and interference of the dual modes in the resonator lead to dual-band filtering with high isolation. As the finite-difference time-domain simulation illustrates, two low-order resonant modes can be effectively triggered by optimizing the waveguide width and spacing gap between the compact resonator and waveguides. In experiment, a double side-coupled microdisk resonator was fabricated on a nanophotonic silicon-on-insulator platform, and dual-band bandpass filtering is realized with an optical isolation higher than 20 dB and an insertion loss lower than 2 dB. The experimental results agree well with our modeling results.
21 citations
TL;DR: In this paper, the authors proposed and demonstrated multi-channel all-optical RZ and carrier-suppressed RZ (CSRZ) to non-return-to-zero (NRZ) format conversions using a same fiber delay-interferometer (DI).
19 citations
TL;DR: A 640 Gbit/s NRZ OTDM signal has been successfully generated for the first time by format conversion of a 640 Gbits/s O TDM signal from RZ to NRZ, with very low power penalty and improved dispersion tolerance compared to the wavelength converted RZ case.
Abstract: A 640 Gbit/s NRZ OTDM signal has been successfully generated for the first time by format conversion of a 640 Gbit/s OTDM signal from RZ to NRZ. First, a coherent 640 Gbit/s OTDM RZ signal is generated by wavelength conversion of the original incoherent OTDM signal utilizing Kerr switching in a highly nonlinear fiber. Second, RZ-to-NRZ format conversion is achieved in a specially designed silicon microring resonator with FSR of 1280 GHz, Q value of 638, high extinction ratio and low coupling loss to optical fiber. A 640 Gbit/s NRZ OTDM signal with very clear eye-diagram and narrower bandwidth than both the original incoherent 640 Gbit/s and the wavelength converted coherent 640 Gbit/s RZ OTDM signals has been obtained. Bit error ratio measurements show error free (<10(-9)) performance at a received power of -30 dBm for all the OTDM channels of the 640 Gbit/s NRZ signal, with very low power penalty (<0.5 dB) and improved dispersion tolerance compared to the wavelength converted RZ case.
TL;DR: In this paper, the effect of compressive strain and p-type modulation doping on the gain, differential gain, and linewidth enhancement factor (a-factor) was investigated.
Abstract: It is demonstrated theoretically that the quantum well (QW) semiconductor optical amplifiers (SOAs) with high differential gain will show fast gain recovery dynamic characteristics. Based on the calculation of energy band structure, the effects of compressive strain and p-type modulation doping on the gain, the differential gain, and linewidth enhancement factor (a-factor) are investigated. The peak of the differential gain spectrum shifts to longer wavelength, and the peak value is significantly enhanced by increasing compressive strain. Meanwhile the gain is obviously increased by increasing the p-type modulation doping concentration. By comparing the gain and phase recovery dynamics in three different types of SOA samples, it is shown that the QW SOA with highest differential gain has the shortest gain recovery time among the three samples.
TL;DR: In this paper, a polarization diversity circuit built on the silicon-on-insulator (SOI) platform, which can be fabricated by a simple process, is presented, based on two identical air-clad asymmetrical directional couplers, which simultaneously play the roles of polarization splitter and rotator.
Abstract: We present a polarization diversity circuit built on the silicon-on-insulator (SOI) platform, which can be fabricated by a simple process. The polarization diversity is based on two identical air-clad asymmetrical directional couplers, which simultaneously play the roles of polarization splitter and rotator. A silicon polarization diversity circuit with a single microring resonator is fabricated on the SOI platform. Only <;1-dB polarization-dependent loss is demonstrated. A significant improvement of the polarization dependence is obtained for 20-Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) demodulation using the polarization diversity circuit, compared to a single microring resonator without polarization diversity.
TL;DR: The 40-Gb/s all-optical logic minterms generation of three input demodulated return-to-zero differential phase-shift-keying signals is demonstrated based on two delayed interferometers and a semiconductor optical amplifier cascaded with two bandpass filters to verify the logic integrity.
Abstract: The 40-Gb/s all-optical logic minterms generation of three input demodulated return-to-zero differential phase-shift-keying signals is demonstrated based on two delayed interferometers and a semiconductor optical amplifier cascaded with two bandpass filters. Experimental demonstration verifies the logic integrity of this scheme. The final results are derived in the on-off keying format with clear open eyes and extinction ratios over 10 dB. The proposed scheme could be extended to realize arbitrary complex logic gates.
TL;DR: This work proposes and demonstrates multi-channel parallel format conversions from the non return-to-zero differential phase shift keying (NRZ-DPSK) to the return- to-zero DPSK (RZ- dpsK) using a single semiconductor optical amplifier (SOA).
Abstract: We propose and demonstrate multi-channel parallel format conversions from the non return-to-zero differential phase shift keying (NRZ-DPSK) to the return-to-zero DPSK (RZ-DPSK) using a single semiconductor optical amplifier (SOA) The simultaneous conversions are based on the cross phase modulation (XPM) effect, which is induced by a synchronous optical clock signal with high input power The XPM adds an identical phase shift onto every input bit, resulting in the phase difference unchanged The input spectra are broadened and a subsequent filter is utilized to extract the specific part to form a RZ pulse 6-channel NRZ-DPSK signals at 40 Gb/s can be converted to the corresponding RZ-DPSK signals with ~-08 to -1 dB power penalty for all the channels
TL;DR: In this article, an arbitrary-order bandwidth-tunable differentiator using a programmable optical pulse shaper, which is based on spatial diffraction and liquid crystal modulation, is theoretically analyzed.
Abstract: We experimentally demonstrate an arbitrary-order bandwidth-tunable differentiator using a programmable optical pulse shaper, which is based on spatial diffraction and liquid crystal modulation. The impact of bandwidth of optical pulse shaper on output power and pulsewidth of differentiation is theoretically analyzed. In the experiment, all first-order, second-order, and third-order differentiators with bandwidths of 80, 160, and 320 GHz are obtained with average deviations of less than 4.2%. The differentiation of pseudorandom nonreturn-to-zero (NRZ) signals at 10 and 20 Gbit/s is also discussed.
TL;DR: In this article, a simple one-dimensional waveguide grating with two parallel air slots is proposed to support low dispersion slow light, which is easier to achieve the perfect flat and straight slow light mode dispersion curve.
Abstract: A novel and simple one-dimensional waveguide grating with two parallel air slots is proposed to support low dispersion slow light. Due to more structural tuning freedoms provided by introduction of the slots, it is easier to achieve the perfect flat and straight slow light mode dispersion curve. Low group dispersion of only 3.38 ps2/mm with a slow light group index of 13 is obtained in a plane wave expansion calculation, which denotes a wide bandwidth of 13.2 nm. This result is also proved by finite-difference time-domain simulation in which the output pulse relative distortion is only 0.96% towards the input pulse.
TL;DR: In this paper, a novel scheme to implement two types of optical differentiators using all-optical phase modulation and linear filtering was proposed, in which the differentiated signals are formed on the optical intensity or optical field of the output signal, which in turn depends on the relative shift between the probe wavelength and the closest notches of a linear filter.
TL;DR: An all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) signals is proposed and experimentally demonstrated and has potential application in future high-speed UWB impulse radio over optical fiber access networks.
Abstract: An all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) signals is proposed and experimentally demonstrated. The binary phase coding is performed based on all-optical phase modulation in a semiconductor optical amplifier (SOA) and phase modulation to intensity modulation (PM-IM) conversion in a fiber delay interferometer (DI) that serves as a multichannel frequency discriminator. By locating the phase-modulated light waves at the positive and negative slopes of the DI transmission spectra, binary phase encoded UWB codes (0 and π) are generated. We also experimentally demonstrate a bipolar UWB coding system with a code length of 4, operating at 1.25 Gb/s. And the decoding is analyzed as well. Our proposed system has potential application in future high-speed UWB impulse radio over optical fiber access networks.
TL;DR: A scheme for high-speed clock recovery from return-to-zero (RZ) signal with microring resonators is presented and results show that clock can be recovered at 40 Gbit/s with short rise- and fall- times.
Abstract: A scheme for high-speed clock recovery from return-to-zero (RZ) signal with microring resonators is presented. By using a silicon microring resonator (MRR) for clock extraction and a 3-order nonlinear series-coupled microring resonator (SCMR) for amplitude equalization, clock pulses with amplitude modulation less than 1 dB can be obtained. The proposed scheme is also designed and numerically studied by 3D full vectorial film mode matching method (FMM) and coupled mode theory (CMT). Simulation results show that clock can be recovered at 40 Gbit/s with short rise- and fall- times.
TL;DR: In this article, a simple design of l-to-2 photonic data distributor is proposed, and a proof-of-concept experiment is performed at 40 Gbit/s employing four-wave mixing and cross gain modulation in a single semiconductor optical amplifier.
Abstract: A simple design of l-to-2 photonic data distributor is proposed. A proof-of-concept experiment is performed at 40 Gbit/s employing four-wave mixing and cross gain modulation in a single semiconductor optical amplifier. Correct output logic signals with high extinction ratios (over 11 dB) and clear open eyes are obtained, without using any additional input light beam. The scheme would be a promising candidate for future ultrafast all-optical signal processing applications.
TL;DR: In this paper, the photonic generation of millimeter-wave (MMW) ultra-wideband (UWB) signal using microfiber ring resonator (MRR) is proposed.
TL;DR: In this article, an all-optical format conversion from return-to-zero differential phase shift keying (RZ-DPSK) to non-return-tozero DPSK was demonstrated by using a delay interferometer and a 1-nm bandwidth filter at 40 Gbit/s.
Abstract: All-optical format conversion from return-to-zero differential phase shift keying (RZ-DPSK) to non-return-to-zero DPSK (NRZ-DPSK) is demonstrated by using a delay interferometer and a 1-nm-bandwidth filter at 40 Gbit/s. The operation principle is theoretically analyzed and numerically simulated with the help of VPI Transmission Maker 8.5. The simulated results are in agreement well with the experimental results. The conversion can be achieved with power penalty of 0.7dB.
TL;DR: In this paper, the authors proposed and demonstrated all-optical polarity and shape-switchable ultrawideband (UWB) Gaussian pulses generation schemes using a single polarization interferometer (PI) or a semiconductor optical amplifier (SOA) cascaded by a PI.
TL;DR: In this paper, a microwave photonic filter with an electrooptic phase modulator and an array waveguide grating, which acts as a detuned two-channel wavelength division de-multiplexer was theoretically and experimentally investigated.
Abstract: We theoretically and experimentally investigate a microwave photonic filter with an electrooptic phase modulator and an array waveguide grating, which acts as a detuned two-channel wavelength division de-multiplexer. In the experiment, a microwave notch filter with a QN factor of 236 and a rejection ratio of 31 dB is obtained by introducing microwave subtraction directly in optical domain. The parameter QN factor is defined to measure the rejection selectivity of a microwave notch filter and corresponding to the Q factor in a microwave bandpass filter. A microwave bandpass filter with a Q factor of 245 and a rejection ratio of 38 dB is also obtained. The relationship between the Q factor of the microwave bandpass filter and the QN factor of the microwave notch filter is measured. The variations of Q and QN versus the detuning of the tunable optical bandpass filter (TOBF), which is incorporated in the recirculating delay line loop, is also measured and discussed. Simulation results about the influences of the wavelength division de-multiplexer and TOBF on the microwave frequency response are also presented and analyzed.
13 Nov 2011
TL;DR: In this paper, a new cascaded microwave photonic filter consisting of two or more infinite impulse response (IIR) filters based on active loops is presented, which can increase the free spectral range (FSR) and the Q value significently by designing the FSR differences of the IIR filters.
Abstract: A new cascaded microwave photonic filter consisting of two or more infinite impulse response (IIR) filters based on active loops. is presented. Owing to wavelength conversion, the interference between the modulated optical signals of different taps from different active loops can be avoided and the stable transmission characteristic of the cascaded filter can then be achieved. The cascaded filter can increase the free spectral range (FSR) and the Q value significently by designing the FSR differences of the IIR filters. The cascaded filter with two IIR filters is demonstrated, and the measured results of a high Q of 3338 and rejection ratio of about 40 dB are obtained. The tunability can also be realized.
TL;DR: In this article, 16-ary all-optical logic minterms for four-line inputs at 40 Gb/s utilizing delay interferometers (DIs) and cascading semiconductor optical amplifiers (SOAs) without any assisting light.
Abstract: We have experimentally demonstrated 16-ary all-optical logic minterms for four-line inputs at 40 Gb/s utilizing delay interferometers (DIs) and cascading semiconductor optical amplifiers (SOAs) without any assisting light. Extinction ratios (ERs) of the intermediate results after the first SOA are all over 11 dB which ensures the capability to cascade to the second one. The final results are in the form of return-to-zero (RZ) format with correct and clear temporal waveforms. The proposed scheme should be a promising candidate for constructing arbitrary more complex logic functions.
13 Nov 2011
TL;DR: In this paper, a model of subwavelength-diameter fiber taper-based Bragg gratings (SWDFT-BGs) is presented and numerically investigated.
Abstract: We come up with a model of subwavelength-diameter fiber taper-based Bragg gratings (SWDFT-BGs) and numerically investigated the chirp characteristics of Bragg gratings written in local single-mode fiber tapers based on coupled-mode theory and transfer matrix method. The effective modal refractive index varies along adiabatic subwavelength-diameter fiber tapers (SWDFTs), which results in an effective chirp in grating period. Additionally, SWDFT-BGs with full width at half maximum (FWHM) up to 4.9 nm and time-delay slope over 25 ps/nm were achieved in simulations. This offers an idea for fabricating single-mode chirped fiber Bragg gratings using uniform phase-mask and paves ways for waveguide dispersion engineering and wide-bandwidth optical filters.
Book•
01 Jan 2011
TL;DR: Erich Kasper Jinzhong Yu Xun Li Xinliang Zhang Jinsong Xia Junhao Chu Zhijiang Dong Bin Hu Yan Shen Editors 25 November 2011 Wuhan, China Organized by WuhAN National Laboratory for Optoelectronics (WNOL) Sponsored by Huazhong University of Science and Technology (UCSE).
Abstract: Erich Kasper Jinzhong Yu Xun Li Xinliang Zhang Jinsong Xia Junhao Chu Zhijiang Dong Bin Hu Yan Shen Editors 25 November 2011 Wuhan, China Organized by Wuhan National Laboratory for Optoelectronics (China) Sponsored by Huazhong University of Science and Technology (China) China Hubei Provincial Science and Technology Department Wuhan East Lake National Innovation Model Zone (Optics Valley of China, OVC) The Optical Society Hubei Provincial Foreign Experts Affairs Bureau Supported by Ministry of Education (China) State Administration of Foreign Experts Affairs (China) National Natural Science Foundation Committee of China Cooperating Organizations IOPInstitute of Physics The Laser Institute of America (United States) IETThe Institution of Engineering and Technology International Biomedical Optics Society IEEE Photonics Society (Singapore and Hong Kong Chapters) Chinese Optical Society Published by SPIE
22 Dec 2011
TL;DR: In this article, a silicon micro-ring resonator tuned to a NRZ-DPSK modulated optical carrier is proposed and demonstrated for the synthesis of monocycle pulses.
Abstract: Ultra-wide band signal generation using a silicon micro-ring resonator tuned to a NRZ-DPSK modulated optical carrier is proposed and demonstrated. Tuning of the coupling regions of the micro-ring enables the synthesis of monocycle pulses.