Room-temperature generation of amplitude-squeezed light from 1550-nm distributed-feedback semiconductor lasers

Experimental results are reported for amplitude squeezed states generated from two kinds of 1550-nm distributed-feedback semiconductor laser at room temperature. Both lasers exhibit excess noise under free-running conditions, but the origin of this noise is different for the two lasers. For one of the lasers the excess noise is reduced by enhancement of the side-mode-suppression ratio. For the other the excess noise that degrades the squeezing is reduced by weak dispersive optical feedback produced by a grating detuned from the maximum of its first-order reflection. Thus the grating is used to convert phase noise into intensity noise. (C) 1999 Optical Society of America [S0740-3224(99)01703-8]. OCIS codes: 270.6570, 140.5960, 140.3490, 270.2500.