Opto-electronic oscillator mediated by acoustic wave in a photonic crystal fiber stimulated in 1 μm band.

An opto-electronic oscillator based on guided acoustic wave Brillouin scattering in a photonic crystal fiber (PCF) stimulated by a light wave in 1 μm band is proposed and demonstrated. A short length of a homemade PCF stimulated by relatively low pump power leads to strong coupling between the pump and probe waves. The oscillation is realized in a feedback loop, in which the acoustic wave bridges the pump and probe.

Time-encoded structured illumination microscopy: toward ultrafast superresolution imaging.

An imaging strategy based on optical time-encoded structured illumination microscopy (TE-SIM) opens the way toward ultrafast superresolution imaging. A proof-of-principle experiment is conducted and the introduced TE-SIM accelerates the generation rate of sinusoidal fringe patterns to an unprecedented speed (dozens of megahertz). At such a high speed, superresolution imaging that surpasses the diffraction limit by a factor of 1.

Compressive sensing based high-speed time-stretch optical microscopy for two-dimensional image acquisition.

In this paper, compressive sensing based high-speed time-stretch optical microscopy for two-dimensional (2D) image acquisition is proposed and experimentally demonstrated for the first time. A section of dispersion compensating fiber (DCF) is used to perform wavelength-to-time conversion and then ultrafast spectral shaping of broadband optical pulses can be achieved via high-speed intensity modulation. A 2D spatial disperser comprising a pair of orthogonally oriented dispersers is employed to produce spatially structured illumination for 2D image acquisition and a section of single mode fiber (SMF) is utilized for pulse compression in the optical domain.

Fast time-lens-based line-scan single-pixel camera with multi-wavelength source.

A fast time-lens-based line-scan single-pixel camera with multi-wavelength source is proposed and experimentally demonstrated in this paper. A multi-wavelength laser instead of a mode-locked laser is used as the optical source. With a diffraction grating and dispersion compensating fibers, the spatial information of an object is converted into temporal waveforms which are then randomly encoded, temporally compressed and captured by a single-pixel photodetector.

Analog photonic link based on the Aulter-Townes splitting induced dual-band filter for OCS and the SOI signal processor.

Analog photonic link (APL) is attractive for its potential high performance of larger dynamic range, tunability, and immunity to electromagnetic interference (EMI). An APL based on the Aulter-Townes splitting (ATS)-effect-induced dual-band filter for optical carrier suppression (OCS) and the SOI signal processor has been proposed and experimentally demonstrated. The bandwidths of the two passbands are approximately 780 MHz, and the interval could be tuned from 8 GHz to more than 80 GHz in simulation.

Blind polarization demultiplexing by constructing a cost function for coherent optical PDM-OFDM.

We propose a training symbols-free polarization demultiplexing method by constructing a cost function (CCF-PDM) for coherent optical PDM-OFDM. This method is applicable for high-speed, wide-bandwidth OFDM signals, different subcarrier modulation formats and long-haul transmission. It shows comparable performance with that of conventional method but without overhead and converges fast.

Compressive spectrum sensing of radar pulses based on photonic techniques.

We present a photonic-assisted compressive sampling (CS) system which can acquire about 10(6) radar pulses per second spanning from 500 MHz to 5 GHz with a 520-MHz analog-to-digital converter (ADC). A rectangular pulse, a linear frequency modulated (LFM) pulse and a pulse stream is respectively reconstructed faithfully through this system with a sliding window-based recovery algorithm, demonstrating the feasibility of the proposed photonic-assisted CS system in spectral estimation for radar pulses.

Broadband RF front-end using microwave photonics filter.

We propose and demonstrate a novel RF front-end with broadened processing bandwidth, where a tunable microwave photonic filter based on optical frequency comb (OFC) is incorporated to accomplish simultaneous down-conversion and filtering. By designing additional phase shaping and time delay controlling, the frequency tunability of the system could be enhanced. More importantly, the beating interferences generated from broadband RF input could also be suppressed, which help to break the limitation on the processing bandwidth.

Time-stretch high-speed microscopic imaging system based on temporally and spectrally shaped amplified spontaneous emission.

In this Letter, a time-stretch high-speed microscopic imaging system based on temporally and spectrally shaped amplified spontaneous emission (ASE) is proposed and experimentally demonstrated. We significantly reduced the complexity and cost of the light source by applying ASE in the time-stretch microscopic imaging system. Furthermore, by slicing and preprocessing the spectrum of the ASE with a Fabry-Perot (F-P) filter, the random intensity vibration of the ASE can be significantly suppressed, which would notably simplify the image recovery process afterward.

Optical serial coherent analyzer of radio-frequency (OSCAR).

Optical serial coherent analyzer of radio-frequency is a novel scheme that enables fast-scanning microwave signal measurements in a large bandwidth. The measurements are performed based on serial channelization realized by using a fast scanning laser source as the local oscillator to down-convert the to-be-measured radio-frequency (RF) signals. Optical coherent detection effectively removes interferences induced by RF's self-beating and guarantees the accuracy of measurements.

Multiwavelength time-stretch imaging system.

A high-speed microscopic imaging system based on a multiwavelength source and time-stretch technique is proposed and demonstrated. We realize an imaging system at 1D scan rate of 80 MHz with 20 resolvable points. This scheme breaks the bottleneck of large bandwidth and high repetition rate in mode-lock lasers and has great potential for imaging system integration.

Multiple-frequency measurement based on serial photonic channelization using optical wavelength scanning.

A serial photonic channelized radio frequency (RF) measurement scheme is proposed and experimentally demonstrated. This scheme can be used for instantaneous multiple-frequency measurement and capturing key parameters of linear frequency modulation signals. Based on high-speed wavelength scanning, this photonic RF channelizer works serially in time domain, and each wavelength labels a certain RF channel.

Widely tunable all-fiber optical parametric oscillator based on a photonic crystal fiber pumped by a picosecond ytterbium-doped fiber laser.

We report on a fully fiber-integrated widely tunable optical parametric oscillator based on a photonic crystal fiber pumped by a picosecond ytterbium-doped fiber laser. The output wavelength of the oscillator can be continuously tuned from 898 to 1047 nm and from 1086 to 1277 nm, which is as wide as 340 nm. In particular, a larger Raman gain peak is simultaneously observed when the pump wavelength is far from the zero-dispersion wavelength in the normal-dispersion regime.

Photonic-assisted multi-channel compressive sampling based on effective time delay pattern.

In this paper, a photonic-assisted multi-channel compressive sampling scheme is proposed with one pseudo-random binary sequence (PRBS) source and Wavelength Division Multiplexing-based time delay. Meanwhile, the restricted isometry property of sensing matrix determined by the optimized time delay pattern is analyzed. In experiment, a four-channel photonic-assisted system with 5-GHz bandwidth was set up, where four-channel PRBS signals were generated by adding fiber-induced constant time delays to four-wavelength modulated PRBS signal, and a signal composed of twenty tones was recovered faithfully with four analog-to-digital converters (ADCs) with only 120-MHz-bandwidth.

An all-fiber continuously time-dispersion-tuned picosecond optical parametric oscillator at 1 μm region.

We report the experimental demonstration of a fully fiber-integrated picosecond optical parametric oscillator. The gain is provided by a 50-meters homemade photonic crystal fiber in the ring cavity. A time-dispersion-tuned technique is used to allow the oscillator to select the oscillating wavelength adaptively and synchronize with the pump pulse train.

A simple photonic generation of linearly chirped microwave pulse with large time-bandwidth product and high compression ratio.

Based on the heterodyne beating between the pre-chirped optical pulse and the continuous wave (CW) light in a wideband photodetector (PD), linearly chirped microwave pulse with time duration of 3.2ns and bandwidth of 33GHz, which yields a large time-bandwidth product (TBWP) of 106 and high compression ratio of 160, is generated in our experiment. Dispersion compensation fiber (DCF) with uniform response across broad bandwidth is used for providing the original linear chirp in our method, which shows the promise to generate linearly chirped microwave pulse with bandwidth of up to THz.

Simple approach for fast real-time line scan microscopic imaging.

A simple fast line scan microscopic imaging approach based on a wavelength-space-time mapping technique has been proposed. With a lab-made subpicosecond pulse laser with 10 dB bandwidth of 12 nm, we experimentally demonstrate a free-space optical apparatus designed for fast line scan imaging of microscopic objects. This system has a spatial resolution of 22 μm, field-of-view of 2.

Compact Q-value enhanced bandpass filter based on the EIT-like effect accompanying application in downconversion APL.

A compact quality factor (Q)-enhanced bandpass filter based on the electromagnetically induced transparency (EIT)-like effect between two-ring resonators was proposed and experimental demonstrated. The enhancement in Q can be 2-3 orders of magnitude compared to the single ring bandpass filter, and a 27 times enhanced bandpass filter with a bandwidth of approximately 4.8 GHz was successfully realized.

Silicon-on-insulator narrow-passband filter based on cascaded MZIs incorporating enhanced FSR for downconverting analog photonic links.

A silicon-on-insulator (SOI) narrow-passband filter based on cascaded Mach-Zehnder interferometers (MZIs) is theoretically simulated and experimentally demonstrated, indicating that the free spectral range (FSR) of the proposed filter can be significantly enlarged by increasing the number of the MZI stages. A filter using three-stage cascaded MZIs structure is successfully realized in the experiment and a 3-dB bandwidth of about 1.536 GHz and FSR about 13.

5×200 Gbit/s all-optical OFDM transmission using a single optical source and optical Fourier transform real-time detection.

An all-optical sampling OFDM scheme using PolMux-DQPSK format with single source is proposed and experimentally demonstrated. 5 × 200 Gb/s AOS-OFDM signal with spectral efficiency of 3.07 bit/s/Hz is successfully transmitted over an 80 km SMF link with real-time detection by optical Fourier transform filters.

16×10Gb/s symmetric WDM-FOFDM-PON realization with colorless ONUs.

A novel symmetric WDM-PON scheme with colorless ONU is proposed. The baseband 4-ASK Fast-OFDM signal is upconverted by an intermediate frequency carrier, reserving a frequency gap between the FOFDM signal and the optical carrier. After distributing different wavelengths to corresponding ONU by AWG, periodic BPFs are employed to extract the optical carriers for upstream transmission, achieving colorless ONUs.

A high spectral efficiency optical OFDM scheme based on interleaved multiplexing.

By multiplexing two OFDM signals with the same channel space and bit rate together in an interleaved mode, a novel optical multiplexing scheme is proposed and experimentally demonstrated. Since the channel space is halved, the spectral efficiency is doubled compared with conventional OFDM. It is proved that the orthogonality between the subcarriers is maintained as long as the data is real.

Broadband tunable optical delay based on real-time Fourier transformation and ramp-type phase modulation.

A new tunable optical delay scheme based on real-time Fourier transformation and ramp-type phase modulation is proposed and experimentally demonstrated. A linearly chirped fiber Bragg grating is adopted to implement the real-time Fourier transformation, and tunable delay is realized by changing the ramp-type modulating signal's period. Experimental results agree well with the theory.

100Gb/s PolMux-NRZ-AOS-OFDM transmission system.

A novel high speed transmission system using all-optical sampling orthogonal frequency multiplexing (AOS-OFDM) technique is proposed and demonstrated. By utilizing polarization multiplexing (PolMUX) and non-return-to-zero (NRZ) format, the total bit rate is 100 Gb/s with high spectral efficiency of 1.6.

Code extraction from encoded signal in time-spreading optical code division multiple access.

A vulnerability that allows eavesdroppers to extract the code from the waveform of the noiselike encoded signal of an isolated user in a standard time-spreading optical code division multiple access communication system using bipolar phase code is experimentally demonstrated. The principle is based on fine structure in the encoded signal. Each dip in the waveform corresponds to a transition of the bipolar code.