Optical phase modulation in an injection locked AlGaAs semiconductor laser

Optical phase modulation by injecting coherent CW light into a directly frequency modulated semiconductor laser is reported. Phase modulation was obtained at up to 800 MHz modulation frequency without distortion for a 1.6 GHz full locking bandwidth. A static phase shift of ¿ took place with a 0.48 mA bias current change in the injection locked laser. Experimental and theoretical results showed that the product of the normalised phase deviation by the frequency deviation and the cutoff modulation frequency is constant.