Transverse Fourier analysis of squeezed light in diode lasers

The transverse properties of squeezed light are studied for a number-squeez ed edge diode laser working in an external-cavity configuration. Light nois e is analyzed as a function of the transverse wave vector transmitted by a single slit at the focal plane of a short focal lens. Noise measurements ob tained by opening the slit centered at the k(x) = 0 position show a minimum squeezing at the slit center that increases up to the full-beam noise-comp ression. Noise is also measured by displacing a single slit of fixed width at the focal plane. The results of this wave-vector dependence are compared with a theory in which the slit is treated as a beam splitter for the inco ming Hermite-Gaussian laser beam. A summation of the noise contributions at each wave vector cannot give the obtained result with the slit being open, which indicates a possible noise correlation of light with distinct wave v ectors. (C) 2001 Optical Society of America.