Spatial quantum noise of laser diodes

Abstract

We experimentally study the transverse distribution of intensity noise in the far field of a single-mode semiconductor laser. We show that a large amount of noise is present in the higher-order nonlasing transverse modes (parallel to the diode junction). Furthermore, correlations between the TE 00 and the TE 10 modes are observed.

30 years of squeezed light generation

“…one has to measure all modes. There are strong correlations between different spatial modes [83]. Some of these modes with negligible power help to significantly reduce the noise (for details see [82] and references there in).…”

Quantum Degeneracy of Microcavity Polaritons

“…This corresponds to the idea that in a single-mode quantum state, photons are randomly distributed in the transverse plane. Such behavior can be tested by ''cutting'' the beam transversally with a razor blade and measuring the intensity noise as a function of intensity [18]. The noise normalized to the shot noise limit should vary linearly with the intensity-the slope is, respectively, positive, negative, or equal to zero if the noise of the total beam is above, under, or at the shot noise level.…”

Quantum limits in the measurement of very small displacements in optical images

“…If the beam is initially centered on the detector, the mean value of the photocurrent difference N − = N A − N B is directly proportional to the relative lateral displacement D of the whole beam with respect to the initial symmetrical configuration, at least for displacements small compared to the beam size. The noise affecting this quantity, sometimes called "position noise", limits the accuracy in the measurement of D. It has been studied experimentally and theoretically for various laser beams [11,12]. When the light beam is in a coherent state, the displacement D sql providing a value of N − equal to this noise is the standard quantum limit in the measurement of a small transverse displacement.…”

“…One finds therefore that considering a partial photodetection as equivalent to a loss is not true in general. One can find in [11] and [12] examples of nontrivial noise variations in partial photodetection, in the case of multimode laser beams with excess noise, providing useful information on the laser used in the experiment.…”