A constant-current–driven semiconductor laser produced a field with amplitude noise reduced to below the standard quantum limit by -1.7 dB (32%) over an entire frequency range from near dc to 1.1 GHz. The amplitude squeezing dependence on laser pump rate and optical loss was in good agreement with theoretical prediction. The new squeezed-state generation principle of high impedance suppression for pump-amplitude fluctuation was thus confirmed experimentally.

• Received 28 September 1987

DOI:https://doi.org/10.1103/PhysRevLett.60.792