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This letter presents a photonic scheme to generate frequency-multiplied microwave signals with nearly constant amplitude. Optical injection locking and an optical fiber active loop filter are utilized to generate a frequency-multiplied microwave signal and equalize its amplitude, respectively. The significance of the scheme is that optical injection locking and nonlinear modulation are simultaneously implemented by a semiconductor distributed feedback laser, making this system compact and low-cost compared with other similar photonic implementations. Corresponding experiments display the effects of amplitude equalization for 10th and 11th harmonics with an initial frequency of 1.5 GHz and an 18th harmonic with an initial frequency of 1 GHz, respectively. The harmonic suppression ratios reach over 20 dB, and the SSB phase noises (

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.

This letter presents the experimental performance of a rate-selectable all-optical packet clock extractor using a Fabry-Perot (F-P) filter, a semiconductor optical amplifier (SOA), and polarization interferometers (PIs). The F-P filter with a low finesse and a free-spectral range (FSR) equal to the lowest packet data rate was used to directly extract the packet clock from the packet data stream, which ensures that the clock locks fast and vanishes quickly. Different PIs, in conjunction with the F-P filter, were used to form comb filters with different FSRs in order to suppress the undesired subharmonic frequencies. The clock then goes into SOA to reduce the low-frequency amplitude noise. We demonstrate packet clock extraction at 10, 20, and 40 Gb/s with the combination filter.