Nonclassical light from a semiconductor laser operating at 4 K

Amplitude fluctuations of the light from a semiconductor lase, operating 4 K, have been measured to be 11% below the shot-noise limit in the detected photocurrent. Weak optical reflection into the laser reduces the squeezing from the expected detector-current laser-current transfer ratio of 25%. Results compare favorably with a theory which includes effects of optical feedback. © 1990 The American Physical Society.