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

Abstract

The amplitude and phase noises of a dual-frequency vertical-external-cavity surface-emitting laser (DF-VECSEL) operating at telecom wavelength are theoretically and experimentally investigated in detail. In particular, the spectral behavior of the correlation between the intensity noises of the two modes of the DF-VECSEL is measured. Moreover, the correlation between the phase noise of the radio-frequency (RF) beatnote generated by optical mixing of the two laser modes with the intensity noises of the two modes is investigated. All these spectral behaviors of noise correlations are analyzed for two different values of the nonlinear coupling between the laser modes. We find that to describe the spectral behavior of noise correlations between the laser modes, it is of utmost importance to have a precise knowledge about the spectral behavior of the pump noise, which is the dominant source of noise in the frequency range of our interest (10 kHz to 35 MHz). Moreover, it is found that the noise correlation also depends on how the spatially separated laser modes of the DF-VECSEL intercept the noise from a multi-mode fiber-coupled laser diode used for pumping both the laser modes. To this aim, a specific experiment is reported, which aims at measuring the correlations between different spatial regions of the pump beam. The experimental results are in excellent agreement with a theoretical model based on modified rate equations.

Noise Investigation of a Dual-Frequency VECSEL for Application to Cesium Clocks

“…VECSEL structures [20], [21]. This simple model was shown to derive from a more complete theory taking spin-flipping effects into account [22].…”

“…While this theory has initially been developed to understand DF-VECSELs operating at telecom wavelengths, we generalized it with respect to Ref. [21] by taking into account the difference between the pump powers that feed the two modes. In Section IV, we describe the measurement of the pump noise, intensity noises, beatnote phase noise, and the correlations between the intensity noises.…”

Noise measurement and modeling of a dual-frequency VECSEL at cesium clock wavelength

“…The experimental results were very well predicted by a theory based on modified rate equations. The validity of this theory has been even more solid after the success of the analysis of the correlation between the different noises [11]. Rich information about the laser can be revealed using this theory.…”

Dual-comb modelocked lasers: semiconductor saturable absorber mirror decouples noise stabilization

“…Our dual comb modelocked laser was initially motivated by the dual frequency VECSEL [36], where the VECSEL is operated in continuous wave (cw). A recent study of noise correlation in such dual-frequency VECSELs [37] could be interesting for the "locked" regime of operation where both beams have the same pulse repetition rate. However, for dual comb spectroscopy applications we need two different pulse repetition rates and our focus in this paper is with regards to the origin of the decoupled timing jitter noise between the two output beams with different pulse repetition rates.…”