Wavelength Conversion in Tapered-Waveguide Laser Diode Amplifiers

Wavelength conversion using cross-gain modulation (XGM) in linear tapered-waveguide semiconductor laser amplifiers (SLAs) has been investigated theoretically and compared with the nontapered semiconductor laser amplifier. For example, we have found that for the linear tapered-waveguide SLA with a 450-mu m cavity length, a higher signal power is required to achieve an extinction ratio similar to that obtained by the conventional SLA with the same cavity length. However, a similar extinction ratio is observed for both conventional and linear tapered-waveguide with the cavity length of 1200 mu m. The ifference between the extinction ratios for tip and down conversions is less severe in a linear tapered-waveguide SLA as compared to that for a conventional SLA. The rise time for the linear tapered-waveguide is observed to be higher than that for the conventional SLA. It is possible to attain extinction-ratio conservation using XGM for both up and down conversions in an SLA with a very long cavity length of 2400 Am. (c) 2005 Wiley Periodicals, Inc.