The Experts below are selected from a list of 705543 Experts worldwide ranked by ideXlab platform
Ninghua Zhu - One of the best experts on this subject based on the ideXlab platform.
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dual chirp fourier domain mode locked optoelectronic oscillator
Optics Letters, 2019Co-Authors: Tengfei Hao, Jian Tang, Nuannuan Shi, Ninghua ZhuAbstract:Optoelectronic oscillators (OEOs) have been widely investigated to generate ultra-pure single-frequency microwave signals. Here, we propose and experimentally demonstrate a dual-chirp Fourier domain mode-locked (FDML) OEO to generate dual-chip microwave waveforms. In the proposed FDML OEO, a frequency-scanning dual-passband microwave photonics filter based on phase-modulation-to-intensity-modulation conversion using an optical notch filter and two laser diodes is incorporated into the OEO cavity. Fourier domain mode-locking operation is achieved by synchronizing the scanning period of the filter to the cavity round-trip time. Tunable dual-chirp microwave waveforms with a large Time-Bandwidth Product are generated directly from the FDML OEO cavity in the experiment, which can be used in modern radar systems to improve its range-Doppler resolution.
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breaking the limitation of mode building time in an optoelectronic oscillator
Nature Communications, 2018Co-Authors: Tengfei Hao, Jian Tang, Jianping Yao, Qizhuang Cen, Yitang Dai, Ninghua ZhuAbstract:An optoelectronic oscillator (OEO) is a microwave photonic system with a positive feedback loop used to create microwave oscillation with ultra-low phase noise thanks to the employment of a high-quality-factor energy storage element, such as a fiber delay line. For many applications, a frequency-tunable microwave signal or waveform, such as a linearly chirped microwave waveform (LCMW), is also needed. Due to the long characteristic time constant required for building up stable oscillation at an oscillation mode, it is impossible to generate an LCMW with a large chirp rate using a conventional frequency-tunable OEO. In this study, we propose and demonstrate a new scheme to generate a large chirp-rate LCMW based on Fourier domain mode locking technique to break the limitation of mode building time in an OEO. An LCMW with a high chirp rate of 0.34 GHz/μs and a large Time-Bandwidth Product of 166,650 is demonstrated.
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arbitrary waveform generation based on dispersion free wavelength to time mapping technique
IEEE Photonics Journal, 2018Co-Authors: Xinyi Zhu, Hao Sun, Ninghua ZhuAbstract:We proposed and experimentally demonstrated an approach of dispersion-free arbitrary waveform generation based on a wavelength-swept laser, for the first time to the best of our knowledge. The system has been proven to generate a variety of waveforms, such as Gaussian pulses, rectangular pulses, and a chirped pulse with a large Time-Bandwidth Product of 273.6. Thanks to the linear relationship of frequency to the time of the wavelength-swept laser, time-domain optical signal exhibits the user-defined shape of the optical spectrum without any dispersive element. Furthermore, the proposed method features simple structure, full reconfiguration, and, especially, the high potential for integration.
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active fabry perot cavity for photonic temporal integrator with ultra long operation time window
Optics Express, 2014Co-Authors: Ningbo Huang, Jose Azana, Ming Li, Reza Ashrafi, Lixian Wang, Xin Wang, Ninghua ZhuAbstract:In this paper, a photonic temporal integrator based on an active Fabry-Perot (F-P) cavity is proposed and theoretically investigated. The gain medium in the F-P cavity is a semiconductor optical amplifier (SOA) with high gain coefficient. Key feature of the proposed photonic integrator is that the length of integration time window is widely tunable and could be ideally extended to infinitely long when the injection current is approaching lasing condition. Based on an F-P cavity with practically feasible parameters, a photonic temporal integrator with an integration time window of 160 ns and an operation bandwidth of 180 GHz is achieved. The Time-Bandwidth Product of this photonic temporal integrator is 28,800, which is about two-orders of magnitude higher than any previously reported results. Gain recovery effect has been also considered and analyzed for the impact on performance of the photonic integrator, followed by the simulation results of the impact of gain recovery.
Jianping Yao - One of the best experts on this subject based on the ideXlab platform.
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breaking the limitation of mode building time in an optoelectronic oscillator
Nature Communications, 2018Co-Authors: Tengfei Hao, Jian Tang, Jianping Yao, Qizhuang Cen, Yitang Dai, Ninghua ZhuAbstract:An optoelectronic oscillator (OEO) is a microwave photonic system with a positive feedback loop used to create microwave oscillation with ultra-low phase noise thanks to the employment of a high-quality-factor energy storage element, such as a fiber delay line. For many applications, a frequency-tunable microwave signal or waveform, such as a linearly chirped microwave waveform (LCMW), is also needed. Due to the long characteristic time constant required for building up stable oscillation at an oscillation mode, it is impossible to generate an LCMW with a large chirp rate using a conventional frequency-tunable OEO. In this study, we propose and demonstrate a new scheme to generate a large chirp-rate LCMW based on Fourier domain mode locking technique to break the limitation of mode building time in an OEO. An LCMW with a high chirp rate of 0.34 GHz/μs and a large Time-Bandwidth Product of 166,650 is demonstrated.
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photonic generation of pseudo random microwave waveform based on a random fiber grating
Optical Fiber Communication Conference, 2018Co-Authors: Hong Deng, Stephen J. Mihailov, Jianping YaoAbstract:A photonic approach to pseudo-random waveform generation based on a random fiber grating is proposed and demonstrated. A pseudo-random waveform with a temporal duration of 10 ns and a Time-Bandwidth Product of 322.4 is demonstrated.
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generation of linearly chirped microwave waveform with an increased time bandwidth Product based on a tunable optoelectronic oscillator and a recirculating phase modulation loop
Journal of Lightwave Technology, 2014Co-Authors: Jianping YaoAbstract:Photonic generation of a linearly chirped microwave waveform with an increased Time-Bandwidth Product (TBWP) based on a frequency-tunable optoelectronic oscillator (OEO) and a recirculating phase modulation loop (RPML) is proposed and experimentally demonstrated, for the first time to the best of our knowledge. In the proposed system, a continuous-wave (CW) light wave is divided into two parts: one is sent to the tunable OEO to generate a frequency-tunable microwave signal and the other is intensity-modulated by a switching signal at an intensity modulator to form a chirp-free optical pulse, which are then sent to the RPML, in which the chirp-free pulse is phase modulated by a parabolic waveform to generate a linearly chirped optical waveform. The recirculation of the linearly chirped optical waveform inside the loop would lead to the waveform to experience multiple phase modulations, thus multiplying its chirp rate. By beating the chirped waveform and an optical sideband from the OEO at a high-speed photodetector (PD), a linearly chirped microwave waveform is obtained. The key significance of the approach is that the chirp rate is significantly increased, leading to a significantly increased TBWP. In addition, the approach allows the generation of a linearly chirped frequency-tunable microwave waveform without using a separate microwave source. The technique is experimentally verified. The generation of a linearly chirped microwave waveform with an increased TBWP by 16 times is demonstrated.
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large time bandwidth Product microwave arbitrary waveform generation using a spatially discrete chirped fiber bragg grating
Journal of Lightwave Technology, 2010Co-Authors: Chao Wang, Jianping YaoAbstract:We propose and experimentally demonstrate an approach to generating large Time-Bandwidth Product (TBWP) microwave arbitrary waveforms based on optical pulse shaping using a single spatially discrete chirped fiber Bragg grating (SD-CFBG). The SD-CFBG functions to perform simultaneously spectral slicing, frequency-to-time mapping, and temporal shifting of the input optical pulse, which leads to the generation of an optical pulse burst with the individual pulses in the burst temporally spaced by the time delays determined by the SD-CFBG. With the help of a bandwidth-limited photodetector (PD), a smooth microwave waveform is obtained. The SD-CFBG is fabricated using a linearly chirped phase mask by axially shifting the photosensitive fiber to introduce a spatial spacing between two adjacent sub-gratings during the fabrication process. By properly designing the fiber shifting function, a large TBWP microwave arbitrary waveform with the desired frequency chirping or phase coding can be generated. An equation that relates the fiber shifting function and the microwave waveform frequency chirping is derived. The photonic generation of large TBWP microwave waveforms with a linear, nonlinear and stepped frequency chirping is experimentally demonstrated.
Andrew M. Weiner - One of the best experts on this subject based on the ideXlab platform.
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low loss ultrawideband programmable rf photonic phase filter for spread spectrum pulse compression
IEEE Transactions on Microwave Theory and Techniques, 2015Co-Authors: Hyoungjun Kim, Amir Rashidinejad, Andrew M. WeinerAbstract:We demonstrate a low-loss, ultrawideband (UWB), programmable radio frequency photonic phase filter utilizing a broadband optical frequency comb, interferometric pulse shaping configuration, and a balanced photodetector for spread spectrum pulse compression. We present UWB linear frequency-chirped pulse compression with bandwidths exceeding 7 GHz. The filter insertion loss for these experiments can be as low as 0.5 dB. In addition, the bandwidth and chirp rate of the phase filter are programmable. To further illustrate the programmability of the proposed filter, we report pulse compression experiments for UWB Costas sequences with bandwidth over 6 GHz. Finally, we perform a spread-spectrum jamming-resistant pulse compression experiment with the chirp filter, where a processing gain of $\sim$ 17.3 dB, proportional to the Time-Bandwidth Product of the filter, enables the recovery of a transmitted UWB signal in the presence of jamming.
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photonic radio frequency arbitrary waveform generation with maximal time bandwidth Product capability
Journal of Lightwave Technology, 2014Co-Authors: Amir Rashidinejad, Andrew M. WeinerAbstract:We present an innovative photonic strategy to generate arbitrary microwave and millimeter-wave signals with maximal Time-Bandwidth Product capability and broadly tunable center frequency. The proposed approach incorporates high-resolution pulse shaping, optical interferometry, and the concept of frequency-to-time mapping in order to enable independent control over the temporal amplitude, temporal phase, and center frequency of the generated waveforms. Numerical simulation and experimental results validate that the Time-Bandwidth Product of these pulses is equal to the upper bound set by the number of independent pulse shaper control elements, extending to more than twice that of conventional frequency-to-time mapping techniques. We thus demonstrate a record photonic arbitrary waveform generation Time-Bandwidth Product of ∼589. Also, a length 15 Costas sequence realization is implemented to further portray the potentials of this technique. Detailed analysis of the repeatability and stability of these waveforms as well as higher order dispersion compensation is provided.
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photonic synthesis of high fidelity microwave arbitrary waveforms using near field frequency to time mapping
Optics Express, 2013Co-Authors: Amir Dezfooliyan, Andrew M. WeinerAbstract:Photonic radio-frequency (RF) arbitrary waveform generation (AWG) based on spectral shaping and frequency-to-time mapping has received substantial attention. This technique, however, is critically constrained by the far-field condition which imposes strict limits on the complexity of the generated waveforms. The time bandwidth Product (TBWP) decreases as the inverse of the RF bandwidth which limits one from exploiting the full TBWP available from modern pulse shapers. Here we introduce a new RF-AWG technique which we call near-field frequency-to-time mapping. This approach overcomes the previous restrictions by predistorting the amplitude and phase of the spectrally shaped optical signal to achieve high fidelity waveforms with radically increased TBWP in the near field region.
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microwave photonic arbitrary waveform generation with radically increased time bandwidth Product
Conference on Lasers and Electro-Optics, 2013Co-Authors: Amir Dezfooliyan, Andrew M. WeinerAbstract:The far-field condition sets strict limits on RF waveform generation via spectral shaping and frequency-to-time mapping. We present a new technique which overcomes previous restrictions and achieves high fidelity arbitrary waveforms with radically increased Time-Bandwidth Product.
Shilong Pan - One of the best experts on this subject based on the ideXlab platform.
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photonic generation of linear frequency modulated waveforms with improved time bandwidth Product based on polarization modulation
Journal of Lightwave Technology, 2017Co-Authors: Yamei Zhang, Fangzheng Zhang, Qingshui Guo, Shilong PanAbstract:Polarization modulation of two phase-correlated, orthogonally polarized wavelengths by a parabolic waveform is a promising way to generate linear-frequency-modulated (LFM) signals, but the Time-Bandwidth Product (TBWP) of the generated LFM signal is intrinsically limited by the achievable modulation index of the polarization modulator (PolM). In this paper, an approach to increase the TBWP of the LFM signal generated by polarization modulation is proposed and comprehensively studied by splitting the electrical parabolic waveforms into N pieces with identical amplitude. Applying the split parabolic signal to the PolM, the total equivalent phase shift would be boosted by N /2 times. As a result, the bandwidth as well as the TBWP of the generated LFM signal is increased by N /2 times. An experiment is carried out. As compared to the scheme using an unsplit parabolic signal, the TBWP is improved by more than 500 times. The relationships between the bandwidth, the time duration, and the TBWP of the generated signal with the parameters of the electrical waveform generator are discussed.
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linearly chirped microwave waveform generation with large time bandwidth Product by optically injected semiconductor laser
Optics Express, 2016Co-Authors: Pei Zhou, Fangzheng Zhang, Qingshui Guo, Shilong PanAbstract:A scheme for photonic generation of linearly chirped microwave waveforms (LCMWs) with a large Time-Bandwidth Product (TBWP) is proposed and demonstrated based on an optically injected semiconductor laser. In the proposed system, the optically injected semiconductor laser is operated in period-one (P1) oscillation state. After optical-to-electrical conversion, a microwave signal can be generated with its frequency determined by the injection strength. By properly controlling the injection strength, an LCMW with a large TBWP can be generated. The proposed system has a simple and compact structure. Besides, the center frequency, bandwidth, as well as the temporal duration of the generated LCMWs can be easily adjusted. An experiment is carried out. LCMWs with TBWPs as large as 1.2x105 (bandwidth 12 GHz; temporal duration 10 μs) are successfully generated. The flexibility for tuning the center frequency, bandwidth and temporal duration is also demonstrated.
Y Ogawa - One of the best experts on this subject based on the ideXlab platform.
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500 ghz optical short pulse generation from a monolithic passively mode locked distributed bragg reflector laser diode
Applied Physics Letters, 1994Co-Authors: Shin Arahira, Yasuhiro Matsui, T Kunii, Saeko Oshiba, Y OgawaAbstract:A 500 GHz optical short pulse train was generated from a passively mode‐locked distributed Bragg reflector laser diode (DBR‐LD). The repetition frequency was thirteen times the fundamental round trip frequency in the LD, and harmonic mode‐locking occurred. The pulse duration was 700 fs and the time‐bandwidth Product was 0.51, very close to the transform‐limited value of a Gaussian waveform, 0.44. To our knowledge, this is the first report on the harmonic mode locking of a monolithic passively mode‐locked laser diode.
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transform limited optical short pulse generation at high repetition rate over 40 ghz from a monolithic passive mode locked dbr laser diode
IEEE Photonics Technology Letters, 1993Co-Authors: Shin Arahira, Yasuhiro Matsui, T Kunii, Saeko Oshiba, Y OgawaAbstract:The fabrication of monolithic InP-based passively mode-locked distributed-Bragg-reflector (DBR) laser is reported. An optical short-pulse train with a duration of 3.5 ps was generated at a repetition rate of over 40 GHz. The Time-Bandwidth Product was 0.43, and it was very close to the transform-limited value of a Gaussian waveform. Peak power of 60 mW has been achieved. This laser is promising as an optical source for a high-bit-rate soliton transmission system. >
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nearly transform limited pulse 3 6 ps generation from gain swtiched 1 55 spl mu m distributed feeback laser by using fibre compression technique
Electronics Letters, 1993Co-Authors: K A Ahmed, H F Liu, N Onodera, P Lee, R S Tucker, Y OgawaAbstract:A train of short and nearly transform-limited pulses (3.6 ps) is generated from a 1.55 μm gain-switched distributed feedback laser by fibre compression. These are the shortest pulses generated at 1.55 μm by using a linear fibre compression technique. The bias current dependence of pulse width and time bandwidth Product is also investigated.
