Broadband Optical Wawelength Shifter

We demonstrate a broadband (>50 nm) wavelength shifter capable of operation at multigigabit/s rate, which makes use of gain saturation in a semiconductor optical amplifier. The device is cascadable, can have large fanout, and produces negligible degradation of signal-tonoise ratio. Such a wavelength shifter will be a key component in optical networks based on wavelength division multiplexing (WDM), wherein a key limitation, at present, is the limited tuning range of laser sources [1]. Moreover, the broadband, high-speed wavelength shifter will permit WDM system architectures that require reuse and reassignment of carrier wavelengths, and may further enable design of novel system architectures. Several types of wavelength shifter have been previously reported [2-4], but none of them are capable of broadband operation at Gb/s rates.