Intensity noise correlations in a two-frequency VECSEL

Abstract

We present an experimental and theoretical study of the intensity noise correlation between the two orthogonally polarized modes in a dual frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The dependence of the noise correlation spectra on the non-linear coupling between the two orthogonally polarized modes is put into evidence. Our results show that for small coupling the noise correlation amplitude and phase spectra remain nearly flat (around -6 dB and 0° respectively) within the frequency range of our interest (from 100 kHz to 100 MHz). But for higher values of the coupling constant the low frequency behaviors (below 1-2 MHz) of the correlation amplitude and phase spectra are drastically changed, whereas above this cut-off frequency (1-2 MHz) the correlation spectra are almost independent of coupling strength. The theoretical model is based on the assumptions that the only source of noise in the frequency range of our interest for the two modes are pump noises, which are white noises of equal amplitude but partially correlated.

Experimental and theoretical studies of a dual-frequency laser free from anti-phase noise

“…Besides, the coupling constant between the two modes being easily adjustable in this laser, we have investigated both experimentally and theoretically the behaviour of the correlation between the intensity noises of the two orthogonally polarized modes. Since the dual-frequency Nd:YAG laser is a class-B type, the present study generalizes our previous work on noise correlations in dual-frequency class-A VECSEL [4] which is free from relaxation oscillations.…”

Intensity- and phase-noise correlations in a dual-frequency vertical-external-cavity surface-emitting laser operating at telecom wavelength

“…Before introducing the noise sources, let us present the rate equations we use for the photon numbers and pop-ulation inversion numbers of the DF-VECSEL [13]:…”

“…The noise properties of such DF-VECSEL are not easy to analyze as the two laser modes are coupled and, in addition to that, phase and intensity fluctuations are linked with each other due to the large Henry factor (α-factor) of the semiconductor gain medium [12]. Previously, we have investigated, both experimentally and theoretically, the spectral behavior of the intensity noises and their correlation [13], and the phase noise spectra of the RF beatnote for different nonlinear coupling between the two modes of an optically pumped dual-frequency VECSEL operating at 1 µm [14]. The aim of the present paper is to report the spectral behavior of intensity noise correlations and phase noise spectra of the RF beatnote for different values of the nonlinear coupling between the two modes for an optically pumped DF-VECSEL operating at 1.55 µm.…”

“…All the experimental results are compared with the predictions from a simple theoretical model based on rate equations, as mentioned in Ref. [13,14]. This permits to probe the generality of this simple theoretical model.…”

“…But, here, we follow the approach of Refs. [13,14] to model the DF-VECSEL using simple rate equations. We indeed know from Ref.…”