Tunable spectral squeezers based on monolithically integrated diamond Raman resonators
E. Granados, Georgios Stoikos, Daniel T. Echarri, K. Chrysalidis, V. N. Fedosseev, C. Granados, Vaila Leask, B. A. Marsh, Richard P. Mildren
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 (Δνp= 7.2 ± 0.9 GHz at λp= 450 nm) to a nearly Fourier-limited single axial mode Stokes pulse (ΔνS= 114 ± 20 MHz at λS= 479 nm). The tuning was achieved by precise adjustment of the resonator temperature, with a measured frequency-temperature tuning slope of ∂ν0/∂T≈ −3 GHz/K, and a temperature dependence of the first-order Raman phonon line of ∂νR/∂T≈ +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 >25× from pump to Stokes pulse.