Tunable spectral squeezers based on monolithically integrated diamond Raman resonators

Abstract

We report on the generation and tuning of single-frequency laser light in a monolithic Fabry–Pérot diamond Raman resonator operating in the visible spectral range. The device was capable of squeezing the linewidth of a broad multi-mode nanosecond pump laser ([Formula: see text] 7.2 ± 0.9 GHz at [Formula: see text] 450 nm) to a nearly Fourier-limited single axial mode Stokes pulse ([Formula: see text] 114 ± 20 MHz at [Formula: see text] 479 nm). The tuning was achieved by precise adjustment of the resonator temperature, with a measured frequency-temperature tuning slope of [Formula: see text] −3 GHz/K, and a temperature dependence of the first-order Raman phonon line of [Formula: see text] +0.23 GHz/K. The Stokes center frequency was tuned continuously for over 20 GHz (more than twice the free spectral range of the resonator), which, in combination with the broad Ti:Sapphire laser spectral tunability, enables the production of Fourier-limited pulses in the 400–500 nm spectral range. The Stokes center-frequency fluctuations were 52 MHz (RMS) when the temperature of the resonator was actively stabilized. Moreover, the conversion efficiency was up to 30%, yielding an overall power spectral density enhancement of [Formula: see text] from pump to Stokes pulse.