Wavelength conversion for frequency-modulated light using opticalmodulation to oscillation frequency of a DFB laser diode

A technique for wavelength conversion for frequency-modulated (FM) light is described. It utilizes the light-injection-induced frequency shift of a distributed-feedback (DFB) laser diode and the frequency-modulated-to-intensity-modulated (FM-IM) conversion function of the Mach-Zehnder (M-Z) optical filter. Input FM light is converted into IM light by the M-Z filter. The IM light is injected into the DFB-LD oscillating at another wavelength, modulating its oscillation frequency. The output from the DFB-LD has an FM signal identical to the input FM light. Thus, wavelength conversion for FM light is achieved. The characteristics of the frequency shift induced by this optical injection were experimentally studied using a λ/4 phase-shift DFB-LD. A wavelength conversion experiment was performed. In the experimental demonstration, FM light at 1.534 μm was converted into FM light at 1.550 μm