All-optical clock recovery and multiwavelength switching using semiconductor optical amplifiers for high-speed optical signal processing.

摘要

Semiconductor optical amplifiers are utilized to perform high-speed optical signal processing as components of an all-optical clock recovery system and a multiwavelength switching system. The performance capabilities and characteristics are investigated in detail.;For all-optical clock recovery, the semiconductor optical amplifier is used as the gain element of an injection-locked, passively modelocked laser oscillator. Experimental demonstrations of clock recovery, including harmonic and sub-harmonic clock generation, are shown for a hybrid WDM/TDM data signal. Results show that less than 10 fJ of data pulse energy is necessary to achieve stable, error-free clock recovery, with small amplitude fluctuations (ΔE/E = 0.018) and timing jitter (Δt/T = 1.3·10 −3). The clock oscillator is shown to be capable of phase tracking the data signal for phase modulation frequencies from 10 kHz to 3 MHz. Lockup time is shown to be less than 16 bits (1.95 μs) when injecting a data signal with less than 10% of the intracavity clock energy (300 fJ/bit), even when the phase mismatch is as large as 0.8π (140°). The clock oscillator takes over 7584 bits (24.3 μs) to dephase when the data signal is no longer injected. At larger injected powers, the clock is capable of locking to a data signal with a wide frequency locking bandwidth of 833 kHz, or 2.9·10−3 fractional bandwidth. The system shows stable clocking for non-optimal data signals with few 1's or many 0's, suggesting that the system is not adversely affected by the data bit pattern.;For multiwavelength switching, the semiconductor optical amplifier is used as the nonlinear switching element inside an optical loop mirror. Multiwavelength switching is demonstrated across a 14-nm bandwidth using a tunable 4-wavelength data signal and a 1.6 pJ/pulse control signal. A minimum switching contrast of 10-dB was measured in the time domain. Switching contrast of at least 13-dB, and as much as 23-dB, was observed in the spectral domain.;The all-optical clock recovery system and the multiwavelength switching system were used together to demonstrate all-optical demultiplexing of a hybrid WDM/TDM signal. A 4λ x 311 Mbit/s data channel is demultiplexed from a 4λ x 2.5 Gbit/s aggregate data signal.