Xiaopeng Xie

Wideband tunable optoelectronic oscillator based on a phase modulator and a tunable optical filter

A widely tunable optoelectronic oscillator (OEO) based on a broadband phase modulator and a tunable optical bandpass filter is proposed and experimentally demonstrated. A tunable range from 4.74 to 38.38 GHz is realized by directly tuning the bandwidth of the optical bandpass filter. To the best of our knowledge, this is the widest fundamental frequency tunable range ever achieved by an OEO. The phase noise performance of the generated signal is also investigated. The single-sideband phase noise is below -120 dBc/Hz at an offset of 10 KHz within the whole tunable range.

Tunable DC-60 GHz RF Generation Utilizing a Dual-Loop Optoelectronic Oscillator Based on Stimulated Brillouin Scattering

A dual-loop optoelectronic oscillator (OEO) based on stimulated Brillouin scattering (SBS) is experimentally demonstrated. Two lasers are utilized to realize the tunability of the OEO. One acts as the signal laser, the other is employed as the pump laser. By directly tuning the wavelength of the pump laser, a widely tunable range from dc to 60 GHz for the RF signal generation can be obtained. To the best of our knowledge, this is the widest fundamental frequency tunable range which has ever been achieved by an OEO. With dual-loop fiber lengths of 2 and 4 km, the single sideband (SSB) phase noise is measured to be -100 dBc/Hz at 10 kHz offset when the oscillation frequency is chosen as 5, 10, or 20 GHz. The side-mode suppression ratio (SMSR) is 35 dB when the oscillation frequency is 10 GHz. The stability of both frequency and power of the proposed OEO is improved with the dual-loop configuration when compared with the singleloop one. The Allan variances of the frequency fluctuation at 1-s average are 1.2 × 10-7 and 4.9 × 10-11 for the single-loop and dual-loop configurations, respectively. Furthermore, a phase noise model based on control theory to evaluate the SSB phase noise performance of the dual-loop OEO based on SBS is detailed for the first time. The experimental phase noise results agree well with the proposed phase noise model at an offset frequency range from 100 Hz to 100 MHz. Among different phase noise tests, the amplified spontaneous emission (ASE) noise induced by SBS is shown theoretically and experimentally to be the dominant source for the phase noise beyond 100-kHz frequency offset in the proposed OEO.

Low-noise and broadband optical frequency comb generation based on an optoelectronic oscillator

A novel scheme to generate broadband high-repetition-rate optical frequency combs and low phase noise microwave signals simultaneously is proposed and experimentally demonstrated. By incorporating an optical frequency comb generator in an optoelectronic oscillator loop, more than 200 lines are generated for a 25 GHz optical frequency comb, and the single-sideband phase noise is as low as -122  dBc/Hz at 10 kHz offset for the 25 GHz microwave signal. 10 and 20 GHz optical frequency combs and microwave signals are also generated. Unlike the microwave frequency synthesizer, the phase noise of the microwave signals generated by this new scheme is frequency independent.

Optical phase modulation based on directly modulated reflection-mode OIL-VCSEL

Optical phase modulation based on directly modulated reflection-mode optically injection-locked VCSEL is investigated based on standard OIL rate equations and reflection-mode OIL model. The phase information of both static and dynamic state is simulated. The difference of static state phase information between transmission- and reflection-mode OIL is numerically analyzed. With specific OIL parameters, the output power of directly modulated OIL-VCSEL remains constant and phase deviation of 0.934π rad is obtained. Results show that a directly modulated OIL-VCSEL can function as a key component in QPSK or 8PSK transmitters. Preliminary 2.5 Gb/s PSK modulation characteristic is demonstrated experimentally.

Tunable DC-60 GHz RF generation based on a dual loop Brillouin optoelectronic oscillator

Tunable RF generation from DC to 60 GHz based on dual loop Brillouin Optoelectronic oscillator is experimentally demonstrated. Frequency and power stability is improved compared with single loop.

Widely Tunable Dual Loop Optoelectronic Oscillator based on a Single-Bandpass Microwave Photonic Filter and a Recirculating Delay Line

A wideband tunable dual loop Optoelectronic Oscillator based on a single-bandpass microwave photonic filter and a recirculating delay line is proposed and experimentally demonstrated. A tunable frequency range from 10.23 to 26.69 GHz is obtained.

Tunable DC-40 GHz RF generation with high side-mode suppression utilizing a dual loop Brillouin optoelectronic oscillator

An agilely tunable DC to 40 GHz RF generation using a dual-loop optoelectronic oscillator based on Stimulated Brillouin Scattering is experimentally demonstrated. The side-mode suppression ratio is measured to be 43.1 dB at 20 GHz.

Microwave Photonic Down-conversion based on a Wideband Tunable Optoelectronic Oscillator

We present a novel microwave photonic down-conversion system based on a wideband tunable optoelectronic oscillator. Microwave signals from 14.8 to 31.0 GHz are down-converted to 1 GHz successfully. The conversion gain is about -55 dB.

50 GHz optical frequncy Comb generation based on an optoelectronic oscillator

50 GHz repetition rate optical frequency comb with very low phase noise is experimentally demonstrated by incorporating an optical frequency comb generator (OFCG) in an optoelectronic oscillator (OEO). To the best of our knowledge, this is the highest repetition rate optical frequency comb ever achieved by an OFCG. What more important is that, the OFCG is driven by the 50 GHz millimeter-wave signal oscillating in the OEO, and no frequency synthesizer is needed. The single-sideband (SSB) phase noise of the 50 GHz signal oscillating in the OEO is theoretically analyzed by the Leeson formula. The calculation result shows that the SSB phase noise could be as low as -125 dBc/Hz at 10 kHz offset with our experimental parameters.

Low Noise and Wideband Optical Frequency Comb Generation Based on an Optoelectronic Oscillator

We propose a scheme to generate wideband optical frequency comb and low phase noise microwave signal simultaneously by incorporating an optical frequency comb generator in an optoelectronic oscillator. 12.5 and 25 GHz combs are generated and phase noise are investigated.