Optical-wavelength switching using distributed-feedback laser diodes

An optical-wavelength converter with tunability greater than 5 AA has been demonstrated using a multielectrode distributed-feedback laser diode (DFB LD) with a saturable absorber. The buried heterostructure GaInAsP/InP LD with first-order grating was fabricated using a MOVPE/LPE (metalorganic vapor-phase epitaxy/liquid-phase epitaxy) hybrid growth method. The p-type electrode was divided into three 100- mu m sections, which can be excited independently through the electrodes. The device emits coherent light only when light input is injected into the saturable absorber, and output wavelength is continuously tuned by the driving currents. This device has high optical gain (input power approximately 330 mu W and output power approximately 1 mW) and can operate at up to 500 MHz. A narrowband optical filter was constructed using the DFB LD amplifier. The DFB LD amplifier selectively amplifies one optical frequency, which can be changed by changing the LD bias current. Extinction ratios greater than 15 dB were obtained for the two optical inputs with a 9.8-GHz frequency difference. The use of the device for optical wavelength-division switching was investigated.<
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