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A study was conducted to analyze wavelength-tunable switching among various channels using the self-injection seeding mechanism. The spacing between various wavelengths was tuned by adjustments in the electrical modulation frequency and the length of the dispersive fiber cavity. No optical bandpass filter was needed to separate two wavelengths. Results indicated the feasibility of switching in the gigahertz frequency range.

An external-cavity configuration for a 1.5-mum InGaAsP semiconductor laser, generating tunable dual-wavelength optical output across a wavelength range of 60.8 nm, is proposed and experimentally demonstrated. The Fabry-Perot (FP) grating-lens external cavity comprised an FP filter, converging lens, totally reflecting mirror and a diffraction grating. The relative intensity variation between the two wavelengths was smaller than 1.2dB and no mode hopping was observed.

The concurrent self-injection seeding of a gain-switched Fabry-Perot laser diode at two wavelengths generates dual-wavelength picosecond optical pulses. The scheme, which uses a fiber mirror to provide optical feedback, allows the electrical modulation frequency and dispersion-shifted fiber length to be modified for tuning the output wavelengths and their spacing, respectively, So far, it has generated single-mode pulses at alternate wavelengths around 1.3 micrometer.