Noise reduction in a dual-frequency VECSEL at telecom wavelength using fully correlated pumping

We demonstrate the noise reduction in a dual-frequency vertical-external-cavity surface-emitting laser at telecom wavelength using fully correlated pumping. A fully in-phase correlated pumping is obtained by polarization combining two single-mode fibered laser diodes in a single-mode fiber. With this pumping, ultra-low noises are observed, i. e. relative intensity noise lower than -140 dB/Hz, and beatnote phase noise suppression by 30 dB, getting close to the spontaneous emission limit. The generalized noise reduction is shown by modeling the beatnote phase noise spectra and relative intensity noise transfer gain depending on the in-phase correlation amplitude.