Reduction of relative intensity noise in 1.3 μm InGaAsP semiconductor lasers

Relative intensity noise (RIN) from 1.3 μm InGaAsP vapor phase regrown buried heterostructure diode lasers with cavity lengths of 100–300 μm and resonant frequencies exceeding 15 GHz is measured for the first time over the 2.5–18 GHz frequency range. We show that the RIN decreases by nearly 8 dB as the cavity length increases from 100 to 300 μm, and that the RIN is also reduced by lowering the active p-doping concentration. The measured RIN is in excellent agreement with the expression derived from the laser rate equations.