Squeezed light from a diamond-turned monolithic cavity

Abstract

For some crystalline materials, a regime can be found where continuous ductile cutting is feasible. Using precision diamond turning, such materials can be cut into complex optical components with high surface quality and form accuracy. In this work we use diamond-turning to machine a monolithic, square-shaped, doubly-resonant LiNbO3 cavity with two flat and two convex facets. When additional mild polishing is implemented, the Q-factor of the resonator is found to be limited only by the material absorption loss. We show how our monolithic square resonator may be operated as an optical parametric oscillator that is evanescently coupled to free-space beams via birefringent prisms. The prism arrangement allows for independent and large tuning of the fundamental and second harmonic coupling rates. We measure 2.6 ± 0.5 dB of vacuum squeezing at 1064 nm using our system. Potential improvements to obtain higher degrees of squeezing are discussed.

Squeezed vacuum states from a whispering gallery mode resonator

“…Replacing the first diamond prism with a prism made of lithium niobate would prevent the outcoupling of the TM-polarized squeezed vacuum mode and consequently cancel γ 1 . Such a technique has already been used together with a monolithic square resonator for generating squeezed vacuum states of light [37], but for pump powers 2 orders of magnitude higher. Finally, the competing nondegenerate modes can be eliminated by employing a single-mode WGMR, which is also a proven technology [38].…”

Squeezed vacuum states from a whispering gallery mode resonator

“…Replacing the first diamond prism with a prism made of lithium niobate would prevent the outcoupling of the TM-polarized squeezed vacuum mode and consequently cancel γ 1 . Such a technique has already been used together with a monolithic square resonator for generating squeezed vacuum states of light [37], but for pump powers two orders of magnitude higher. Finally, the competing nondegenerate modes can be eliminated by employing a single-mode WGMR, which is also a proven technology [38].…”

Fabrication of ultrahigh-precision hemispherical mirrors for quantum-optics applications

“…State-of-the-art diamond turning can produce low-NA optical surfaces 50 mm in diameter with peak-to-valley surface deviations of 150 nm 10 and local surface roughness below 0.4 nm 22 . This sub-wavelength precision has been utilized in quantum optics applications such as laser mode converters [23][24][25] , monolithic microcavities 26 , and other resonators 27 .…”