Relative intensity noise (RIN) from 1.3 &mgr;m InGaAsP vapor phase regrown buried heterostructure diode lasers with cavity lengths of 100–300 &mgr;m 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 &mgr;m, and that the RIN is also reduced by lowering the activep‐doping concentration. The measured RIN is in excellent agreement with the expression derived from the laser rate equations.