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A self-starting multiple microwave waveform signal generator based on a dual-loop optoelectronic oscillator (OEO) is proposed. The structure of the dual-loop OEO with two wavelengths can suppress the random beating noise effectively and generate the microwave signal with low phase noise (−119.8 dBc/Hz at 10 kHz). Then square waveform is generated by setting the modulation index to be 1.15. Sawtooth (Reversed-sawtooth) waveform is obtained by combining a square and a frequency doubling sinusoidal signal which is got by setting the bias of the other MZM driven by OEO at the null point (maximum point). The triangular waveform is obtained by combining two oscillation signal envelopes with a relative 1/4 period time delay, when the modulation index of the MZM is set to 0.7555. The operation principle is theoretically analyzed and simulated. In experimental demonstration, full-duty-cycle and high quality square, sawtooth (reversed-sawtooth) and triangular waveform signals with low phase noise at 4.9641-GHz are achieved. An external synthesizer is replaced by the high-quality microwave signal in this structure.

A novel scheme of a highly stable dual-wavelength short optical pulse source (SOPS) based on a dual-loop optoelectronic oscillator (OEO) with two wavelengths is demonstrated. The structure of the dual-loop OEO with two wavelengths can suppress the random beating noise effectively and generate the microwave signal with low phase noise ( $-$ 122.4 dBc/Hz at 10 kHz) . It consists of two directly modulated lasers and a phase modulator (PM) . The light that is directly modulated by the large signal generated from the OEO is injected into the PM to achieve remarkable chirp. Then, by optimizing the length of the dispersion compensating fiber, the optical pulses are further compressed. In the experiment, the SOPS with dual wavelengths is generated simultaneously. The repetition rate, pulse width, and timing jitter of the SOPS are 10 GHz, 2.9 ps, and 12.5 fs, respectively. In particular, the loop drift of the OEO is effectively compensated by fiber stretchers using phase-locked-loop technology. The frequency drift of the microwave signal is less than $\pm$ 73.3 mHz for a long-term measurement with a duration of 1 h. Therefore, the long-term stability of SOPS is guaranteed.

A novel stable multiwavelength single longitudinal mode (SLM) dual ring Brillouin fiber laser is proposed and demonstrated. Dual ring configuration with 100 and 10 m length of single mode fiber guarantees each Stokes and anti-Stokes waves in SLM status. Linewidth of the first Stokes wave is below 4 kHz with 60 dB sidemode suppression value. 7 stable SLM lasing wavelengths including the pump with a 5 dB bandwidth of 0.5, 0.084 nm wavelength spacing and 15 dB average optical signal-to-noise ratio are generated through the cascaded SBS and degenerate FWM process. The laser can freely be tuned 30 nm range from 1535 to 1565 nm. The power fluctuation of the first Stokes wave is about 8 % measured by Data Acquisition System in 1 h.

A novel dual-loop optoelectronic oscillator (OEO) with different wavelengths is demonstrated. The principle of OEO is analyzed theoretically. There is almost no beating noise due to the optical domain dual-loop with different wavelengths. In our experiment, a 20-GHz radio frequency (RF) with high quality is obtained. The phase noise of the microwave signal is measured to be -120.6 dBc/Hz at 10 kHz. The loop drift of the OEO is compensated by a fiber stretcher using phase-loop locked technology and the stability of the RF has been improved greatly. The frequency drift of the OEO system is

A novel single longitudinal mode (SLM) Brillouin fiber laser (BFL) with cascaded ring (CR) Fabry-Perot resonator is proposed and demonstrated. By optimizing the CR length of the single mode fiber cavity at 100 m (or 50 m) and 10 m, stable SLM operation is obtained. Therefore, the threshold power is lower and linewidth is narrower than that of previously reported BFL with 10 m (or 20 m) single cavity. Additionally, there is no additional attenuation except intrinsic loss of optical devices. The measured linewidth with 60 dB (or 45 dB) improved value of side mode suppression ratio is 0.41 kHz (or 3.23 kHz), which is three (or two) orders of magnitude than that of the pump. Using a stabilizing feedback loop based on autotracking technique with polarization maintaining fiber-based optical delay line, the SLM BFL exhibits good performance with 6% power fluctuation in 1 h.

We experimentally demonstrate simultaneous 3R regeneration of 4 $\times$ 40-Gbit/s WDM channels, which is based on the four-wave mixing (FWM) in a single dispersion-shifted fiber. The multichannel 3R regeneration performance is validated by bit-error rate (BER) measurements. Receiver powers at a BER of $10^{-9}$ are improved by 5.2 dB, 4.8 dB, 3.3 dB, and 3.9 dB for the four WDM channels, respectively. Mitigation of the interchannel nonlinearities is achieved mainly through an interchannel 0.5-bit slot time delay, which is introduced by differential group delay. Bidirectional propagation and polarization multiplexing are also applied to relieve the interchannel FWM.

Tunable all-optical wavelength conversion (AOWC) of a 40-Gb/s RZ-OOK data signal based on cascaded second-harmonic generation (SHG) and difference-frequency generation (DFG) in a Ti:PPLN waveguide is demonstrated. Error-free performances with negligible power penalty are achieved for the wavelength-converted signal at 1535, 1538, 1541, 1551, 1554, and 1557 nm, respectively.

A novel distributed optical fiber vibration sensing system based on polarization detection is proposed and demonstrated. A Faraday rotator mirror is employed at the end of the system, which eliminates the slow polarization variation of signal light and only responses to rapid polarization change caused by external vibration interference. Based on the sensing signal characteristics, the location of polarization disturbance point can be detected accurately. Experiments on polarization controller simulation and actual vibration detection show that a higher localization accuracy better than 1% is successfully obtained in 13.8 km, 21.2 km and 35.8 km sensing fibers systems.

We experimentally demonstrate a regenerative multiwavelength conversion (MWC) of an input 10-Gbit/s RZ signal to four output copies by using a single semiconductor optical amplifier (SOA) and a tunable band pass filter (TBPF). Experiment results indicate that improvements in detected Q factor can be observed because of the compression of the input noise. Furthermore, as the probe light we used is a multiwavelength pulses-train with the same frequency as the data signal, this configuration can realize 3R regenerative MWC without any change. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 466–469, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24095

We propose a 40 Gb/s all optical 3R regeneration system. A high Finesse Fabry-Perot (F-P) filter (FSR = 40 GHz, finesse = 1012) and a gain-saturated SOA are used to extract 40 GHz clock. Before the clock extraction, 40 Gb/s RZ optical signals are converted into a stable wavelength after noninverted wavelength conversion based on the XPM of a single SOA. In the all optical decision, dual SOAs in series were used to lengthen active region of SOA. The 40 Gb/s degraded RZ signals are regenerated based on the XPM of dual SOAs in series, when a 0.26-nm OBPF is blue shifted with respect to the wavelength of extracted clock. The experimental results show better eye opening, the decreased timing jitter from 5 to 1.4 ps and the 15 dB improved optical signal to noise ratio (OSNR). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1807–1810, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23473

An all-optical frequency-upconversion is presented by injecting a low bit rate signal into a Fabry-Perot laser diode (FP-LD) without any radio-frequency local oscillator. One of the FP-LD lasing modes is locked by generated sideband through four-wave-mixing effect in FP-LD. The generated microwave subcarrier could be tunable by varying the power and polarization of the injected signal. The input signal at the data rate of 1.25, 2.5, and 2.7 Gb/s with nonreturn-to-zero format are upconverted to a subcarrier modulation signal at upcoversion frequencies of 20, 10, and 16.2 GHz, respectively. The single sideband phase noise of -81.2 and -87.7 dBc/Hz (10-kHz frequency deviation) at 16.2-GHz subcarrier are demonstrated. The difference of sidemode suppression ratio at the FP-LD output point is also analyzed.

We propose a novel scheme for simultaneous retiming and reshaping of two wavelength-division-multiplexing channels using two independent phase clock pump and polarization multiplexing in fiber-optic parametric amplification, with the benefits of suppressing the interchannel cross-phase-modulation effect induced by the clock pumps and four-wave-mixing crosstalk. Operation of two 10-Gb/s channels is demonstrated experimentally. In both single- and dual-channel operation, eye diagrams after regeneration are significantly cleared with pulsewidth narrowed, and the nonlinear interferences are effectively reduced. An average 2-dB power penalty improvement at a bit-error rate of 10-9 is obtained in both single- and dual-channel operation.

A WiMedia-compliant MB-OFDM UWB transmission system is demonstrated, using low-cost transceivers, over up to 50 m long 1 mm PMMA graded-index plastic optical fibre. UWB signal is downconverted to intermediate frequency and transmitted over graded-index plate optical fibre with an overall error vector magnitude penalty 7 dB.

A novel photonic technique to generate millimeter-wave signal is presented. By utilizing an optical phase modulator driven by a 10 GHz electrical signal, high-order modulation sidebands are generated on an optical carrier. In addition, a multiwavelength Brillouin fiber laser (BFL) configuration, acted as multitap notch filter, is used to eliminate unwanted modulation sidebands and keep desired harmonic components. Unlike conventional Brillouin selective sideband amplification or other filtering technology, this technique require neither more external light sources to provide Stokes waves nor wavelength matching between light source and filters. The output of the system is dominated by two high-order sidebands in the optical domain, separated by desired harmonic of the modulation frequency. Signal multiplication is simulated and experimentally demonstrated. The operation range is only limited by the amount of phase shift achieved in the phase modulator. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1683–1685, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24408

An all-optical frequency-upconversion based on fractional talbot effect is experimentally reported. The 2.5-Gb/s baseband signal carried on 10GHz pulse trains is upconverted to 40GHz millimeter wave after 18.49km transmission via repetition frequency multiplication of pulse trains. The phase noise of the 40GHz is as well as −92dBc/Hz at 10kHz frequency detuning. This scheme can operate in 60GHz band by employing the appropriate fiber length based on fractional talbot effect.

A novel scheme to realize all-optical logic gates is proposed bases on nonlinear polarization rotation (NPR) in high nonlinear fiber (HNLF). Two optical signals A and B with return-to-zero data format are injected into the HNLF together with a continuous wave C. Thanks to the optical power variation in HNLF, nonlinear birefringence will be induced between the two polarization axes. Thus it results in the nonlinear polarization rotation of the lightwave in the HNLF. Both the optical signal and continuous wave are filtered out at the output of HNLF using optical band-pass filter. By adjusting the optical power and polarization of the optical signal as well as the polarization of the polarizer with respect to the polarization of optical signal/continuous wave, multiple all-optical logic gates can be realized. Theoretical analysis of the simultaneously realization of the multiple optical logic gates based on NPR in HNLF is provided. And we demonstrated the feasibility of the scheme by realizing all optical “and”, “not”, “nxor”, “A • B”, “A• B ”, half-adder and half-subtracter at 10Gb/s operation.

Simultaneously wavelength conversion of two input data signals based on four-wave mixing (FWM) in a single semiconductor optical amplifier (SOA) is proposed. The two input data signals in the wavelength conversion have a poor extinction ratio (ER) and the data "0" and data "1" are orthogonally polarized. When properly setting the relative polarization state of the two unconventional signals, replicas of the two input signals can be obtained at the idler's wavelength. Simultaneous wavelength conversion for two 10-Gb/s channels is demonstrated experimentally. The ER of two input signals is 4.83dB and 4.81dB respectively before wavelength conversion, while the ER of converted signals is 11.75dB and 10.34dB respectively.

A high frequency optoelectronic oscillator (OEO) using only low frequency optical and microwave devices is attractive as it provides a low cost and high quality solution at the same time. In this paper, a novel OEO scheme is reported. The proposed optoelectronic oscillator includes a 5GHz directly modulated DFB laser, an optical circulator, a 10GHz photodetector, a 10GHz RF amplifier, and a bandpass RF filter with a central frequency at 5GHz. The OEO oscillates at the 5GHz and with a continuous wave injected into the directly modulated DFB laser, higher harmonics will be generated. The harmonic order can be controlled by the frequency difference between the free running DFB laser and injection lightwave. An optical domain combined dual-loop configuration with polarization-beam splitter and a polarization-beam combiner is employed to suppress the sidemodes in each single loop. Experiment results are proposed to verify the scheme, in which 40GHz microwave is obtained.

40 Gb/s optical demultiplexing with amplitude regeneration is demonstrated based on data pump fiber-optical parametric amplification while a 10 GHz short pulse is used as the probe. Four 10 Gb/s output channels with at least 14 dB extinction ratio enhancement and an average 5.5 Q factor is obtained after demultiplexing.

We propose a novel technique to achieve optical frequency up-conversion in millimeter wave band without any local microwave oscillator. By utilizing injection locking of Febry-Perot Laser diode, a suitable negative dispersion device and polarization interferometer, a 2.5Gb/s baseband signal is frequency up-conversion to a subcarrier modulation signal at 30.8GHz.

We propose a novel technique to extent the tunable range of the RF frequency generated by optoelectronic oscillators. By utilizing injection locking of Febry-Perot Laser diode rather than the commonly used radio-frequency bandpass filter, a tunable range from 11.074 GHz to 39.400GHz is demonstrated experimentally.

Multiband OFDM UWB transmission over 1-mm core diameter graded-index plastic optical fiber is demonstrated using a low-cost and off-the-shelf transceiver. We obtain overall EVM penalties of less than 7 dB for 50-m plastic optical fiber.

40-Gb/s 2-Channel all-optical 3R regeneration with simultaneous wavelength conversion has been realised by a fiber parametric amplifier(FPA) with the data signal to be regenerated as the pump,eliminating the unequal suppression of noise between bit0 and bit1. Signal to noise ratio is improved respectively from 2.7,2.4 to4.9,5.2.

A novel approach is proposed to reduce the cross phase modulation between multiple clock pump in the multi-wavelength optical decision based optical fiber parametric amplifier. The dispersive media is used to preprocess the pump clock, and then the clock pump is changed from intensity modulation into phase modulation. In our experiment, cross phase modulation is obviously restrained between the adjacent channels.

Short locking and unlocking time is essepecially important in the packet clock recovery, as it determines the network resource utilization. This paper presents a novel 10-GHz all-optical packet clock extractor with ultrafast locking and unlocking time via self-phase modulation (SPM) effect of the semiconductor optical amplifier (SOA). Low finesse Fabry-Perot (F-P) filter and a saturated SOA, in cascade, are used to directly extract the packet clock from the data stream. An optical bandpass filter(OBPF) is used to filter out the red-shifted parts of the packet clock in order to reduce the locking and unlocking time. We analytically investigate the impact of the locking and unlocking time thanks to the self-gain modulation (SGM) effect and self-phase modulation(SPM) effect induced by the SOA, and demonstrate 10GHz clock extraction with the establishing time of 200ps and vanishing time of 600ps experimentally.

We demonstrate a tunable chromatic dispersion (CD) compensation technique using a semiconductor optical amplifier (SOA) and a coil of dispersion compensation fiber (DCF). Based on cross-phase modulation (XPM) in the SOA, the transient chirp of the received signal can be adjusted by tuning the drive current of the SOA and the power of clock pulse. In this way, a 10-Gbit/s tunable CD compensation setup, ranging from -40ps/nm to 60ps/nm, is realized without changing the length of the DCF.

A time- and wavelength-interleaved optical pulse source, which is based on spectral slicing and dispersion management, is proposed and experimentally demonstrated. The pulse source has a simple configuration, and both the repetition rate and the wavelength channels can be tuned easily.

We present a compact short pulses source, in which the pulses generated by large-signal directly modulated laser diode are phase-modulated, and it can compress the pulse from 30ps to 5.3ps with 184fs timing jitter.

We demonstrate a novel 40-Gb/s all-optical serial to parallel converter (AOSPC), which can convert 40-Gb/s serial optical signals to 4-channel 10-Gb/s parallel optical signals. Moreover, based on the sequential multi-wavelength conversion the AOSPC shows the regeneration ability.

We experimentally demonstrate a 4×10-Gb/s optical multicast scheme using a semiconductor optical amplifier (SOA) and a single optical source, which produce a 10-GHz multi-wavelength pulse-trains used as the probe light of the SOA. The multicast principle is based on the multi-wavelength conversion (MWC) by means of the interaction of both cross gain modulation (XGM) and transient cross phase modulation (T-XPM) of the SOA. Because of the nonlinear amplification of SOA, the 4 output copies are regenerated with respect to the input degraded signal. This scheme is very simple and allows photonic integration.

A novel 10Gbit/s all-optical packet clock extractor, which comprises a Fabry-Perot (F-P) filter and a semiconductor optical amplifier (SOA), is proposed in this paper. Low Finesse Fabry-Perot (F-P) filter was used to directly extract the packet clock from the data packet stream, which ensures that the clock locks fast and vanishes quickly. The clock, amplitude modulated as a result of low-Q filter, then goes into SOA to reduce the low-frequency amplitude noise. The impact of F-P filter and SOA on the locking and unlocking time of the packet clock is theoretically analyzed. The result shows that the locking time is reduced while the unlocking time is increased, due to the self-gain modulation (SGM) effect. We demonstrate instantaneous 10.075GHz clock extraction experimentally with the establishing time of about 8 code-periods and vanishing time of about 22 code-periods.

We firstly derive the mathematical expression of degree of polarization (DOP) for Gauss pulse sequence, then analysis theoretically the relationship between DOP and differential group delay (DGD). The relevant experiments well demonstrate the relationship of DOP-DGD. We get the conclusions that the DOP-DGD curve is independent of fibre dispersion, line chip, and bit rate, and are affected by the width of optical spectrum and splitting ratio. Based on the theory, we successfully complete an automatic PMD compensation system for first-order PMD, which can compensate PMD in the optical link in real-time. The response time of compensation system can reach several milliseconds.

We demonstrate a scheme for long-range, high-precision absolute distance measurement based on frequency detection using two optoelectronic oscillators to convert distance information to frequency information. The two-oscillator design offers the unique advantage of self-referencing. By taking advantage of the accumulative magnification theory, the error of the measured distance is decreased by approximately 10⁵ fold, which significantly improves the precision of the measured distance. In our experiments, the maximum error is ±1.5 μm at an emulated distance of approximately 3.35 km, including a drift error of approximately 1 μm in the air path due to the variation of environmental conditions. The highest relative measurement precision achieved in our current system is 4.5×10⁻¹⁰.

In this paper, a figure-8 laser based on a semiconductor optical amplifier (SOA) for generating dark pulses is proposed. By adjusting the polarization controller, dark pulses with repetition frequency from 9.10 to 33.44 MHz are generated. The pulse widths are from 74.26 to 19.96 ns. The laser consists of an SOA asymmetrically placed in a short fiber loop. Its switching time is determined by the off-center position of the nonlinear element within the loop. Pulses transmitting in the clockwise and counterclockwise directions have the same widths. Then, the two pulses with the same widths overly together and form the dark pulse.

We show a simple, convenient, and cost-effective scheme for tunable frequency upconversion at millimeter-wave band without a local oscillator. By launching a 2.5-Gb/s directly modulated baseband signal into a Fabry-Perot laser diode (FP-LD), the mode of the FP-LD is locked by the high-order sideband of the injected signal. The beating frequency of the injection-locked mode and the injected signal can generate upconversion subcarriers. In our experiment, tunable frequency subcarriers of 28.4, 29.3, and 30.5 GHz are obtained without any radio-frequency local oscillator. The single sideband phase noises of ?83.88, ?76.36, and ?78.54 dBc/Hz @ 10 kHz (at 28.4-, 29.3-, and 30.5-GHz subcarriers, respectively) are shown. The proposed scheme has potential to generate much higher frequency carriers.

A time- and wavelength-interleaved optical pulse source, which is based on spectral slicing and dispersion management, is proposed and experimentally demonstrated. The pulse source has a simple configuration, and both the repetition rate and the wavelength channels can be tuned easily.

By both chirp compression and soliton compression, 10 GHz 1.6 ps optical pulses with 84 fs timing jitter are generated, which have the characteristics of simple system configuration, low timing jitter, repetition rate is easy to tune, and operation at modest signal powers.

We demonstrate simultaneous regeneration of 4×160-Gbit/s signals in a HNLF. The receiver powers at the BER of 10-9 are improved by 1.9 dB, 1.8 dB, 1.6 dB and 1.5 dB for the four channels, respectively.