Ye Deng

Multichannel optical filters with an ultranarrow bandwidth based on sampled Brillouin dynamic gratings

We first propose a multichannel optical filter with an ultra-narrow 3-dB bandwidth based on sampled Brillouin dynamic gratings (SBDGs). The multichannel optical filter is generated when an optical pulse interfaces with an optical pulse train based on an ordinary stimulated Brillouin scattering (SBS) process in a birefringent optical fiber. Multichannel optical filter based on SBDG is generated with a 3-dB bandwidth from 12.5 MHz to 1 GHz. In addition, a linearly chirped SBDG is proposed to generate multichannel dispersion compensator with a 3-dB bandwidth of 300 MHz and an extremely high dispersion value of 432 ns/nm. The proposed multichannel optical filters have important potential applications in the optical filtering, multichannel dispersion compensation and optical signal processing.

Ka-Band Tunable Flat-Top Microwave Photonic Filter Using a Multi-Phase-Shifted Fiber Bragg Grating

A tunable single-bandpass microwave photonic filter (MPF) with a narrow and flat-top shape operating in high frequency range is proposed and experimentally demonstrated, using a specially designed multi-phase-shift fiber Bragg grating (FBG) cascaded with a programmable optical filter (POF). The key device in the proposed MPF is the multi-phase-shift FBG, providing a flat-top passband with a narrow 3-dB bandwidth of 813 MHz in transmission. Consequently, in the MPF, a single passband with a 3- and 20-dB bandwidths of 840 MHz and 2.43 GHz is achieved, respectively. Moreover, an operating frequency range from 27.1 to 38.1 GHz is realized by tuning the wavelength of the optical carrier and adjusting the transfer function of the POF. To the best of our knowledge, this proposed filter provides the highest tunable frequency coverage in Ka-band ever reported for MPFs with a single narrow and flat-top passband.

Reconfigurable Optical Signal Processing Based on a Distributed Feedback Semiconductor Optical Amplifier

All-optical signal processing has been considered a solution to overcome the bandwidth and speed limitations imposed by conventional electronic-based systems. Over the last few years, an impressive range of all-optical signal processors have been proposed, but few of them come with reconfigurability, a feature highly needed for practical signal processing applications. Here we propose and experimentally demonstrate an analog optical signal processor based on a phase-shifted distributed feedback semiconductor optical amplifier (DFB-SOA) and an optical filter. The proposed analog optical signal processor can be reconfigured to perform signal processing functions including ordinary differential equation solving and temporal intensity differentiation. The reconfigurability is achieved by controlling the injection currents. Our demonstration provitdes a simple and effective solution for all-optical signal processing and computing.

Optical Pulse Generation Based on an Optoelectronic Oscillator With Cascaded Nonlinear Semiconductor Optical Amplifiers

This paper presents a high-repetition-rate pulse train generator incorporating an optoelectronic oscillator based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). The optoelectronic oscillator is used to generate a high-stability microwave signal, by which an optical pulse train is generated using FWM effect in cascaded SOAs. The key feature of this work is that no external microwave signal source is needed for generating an optical pulse train. An optical pulse train with a repetition rate of 10 GHz and a pulsewidth of 19 ps is experimentally generated. The pulsewidth and the repetition rate can be tunable and are experimentally demonstrated.

Experimental demonstration of a multi-target detection technique using an X-band optically steered phased array radar.

An X-band optically-steered phased array radar is developed to demonstrate high resolution multi-target detection. The beam forming is implemented based on wavelength-swept true time delay (TTD) technique. The beam forming system has a wide direction tuning range of ± 54 degree, low magnitude ripple of ± 0.5 dB and small delay error of 0.13 ps/nm. To further verify performance of the proposed optically-steered phased array radar, three experiments are then carried out to implement the single and multiple target detection. A linearly chirped X-band microwave signal is used as radar signal which is finally compressed at the receiver to improve the detection accuracy. The ranging resolution for multi-target detection is up to 2 cm within the measuring distance over 4 m and the azimuth angle error is less than 4 degree.

Background-Free Microwave Signal Generation Based on Unbalanced Temporal Pulse Shaping

We propose a new method to generate background-free high-frequency pulsed microwave signal based on an unbalanced temporal optical pulse shaping (TPS) system and balanced photodetection. The proposed system consists of a polarization modulator and an unbalanced TPS system realized by two conjugate dispersion elements. The carrier frequency of the pulsed microwave signal could be tuned by changing the residual dispersion of the TPS. The proposed method is theoretically analyzed and experimentally demonstrated. The experimental results show that the carrier frequency of the generated microwave pulse could be tuned over a broad frequency range. Moreover, the generated microwave pulse signal is background-free by suppressing the baseband frequency components using balanced photodetection.

Fully characterization of a DFB-SOA based active optical filter

A fully characterization of an active optical filter based on an equivalent-phase-shifted DFB-SOA in transmission is experimentally demonstrated. The influences of driven current on transmission characteristics of the DFB-SOA are analyzed.

Tunable single passband microwave photonic filter based on DFB-SOA-assisted optical carrier recovery

A widely tunable single-passband microwave photonic filter (MPF) based on a distributed-feedback semiconductor optical amplifier (DFB-SOA) is proposed and experimentally demonstrated in this paper. The fundamental principle is to recover the suppressed optical carrier from a passband optical filter by the wavelength-selective amplification via a DFB-SOA. A microwave signal is then generated by beating the recovered optical carrier with the phase-modulated lower sideband, and thus, an MPF is achieved with the shape of the passband optical filter that is mapped from the optical domain to the electrical domain. By tuning the central wavelength of the passband optical filter, a single-passband MPF with a frequency tuning range from 5 to 35 GHz is obtained. The 3-dB bandwidth and the out-of-band suppression ratio are measured to be 4 GHz and 20 dB, respectively. In addition, the tunability of the MPF that is dependent on the driven current of the DFB-SOA is also experimentally investigated.

Tunable fractional-order photonic differentiator using a distributed feedback semiconductor optical amplifier

Abstract. We propose a tunable fractional-order photonic differentiator based on a distributed feedback semiconductor optical amplifier (SOA) working in reflection mode. The phase shift at the resonant wavelength can be adjusted by controlling the current injected into the DFB-SOA, which can implement the fractional-order differentiation. A 60 ps Gaussian pulse is temporally differentiated with a tunable order range from 0.7 to 1.3.

Proposal of Sampled Brillouin Dynamic Gratings

We first report and numerically investigate sampled Brillouin dynamic gratings (SDBG) realized in optical fibers. The introduction of sample as an extra degree of freedom opens up possibilities for frequency control of stimulated Brillouin scattering.