Monolithic Optical Parametric Oscillators for Quantum Optics

Elizaveta P. Kozhina

Hidehiro Yonezawa, Koyo Nagashima, Akira Furusawa

We generate squeezed state of light at 860 nm with a monolithic optical parametric oscillator. The optical parametric oscillator consists of a periodically poled KTiOPO(4) crystal, both ends of which are spherically polished and mirror-coated. We achieve both phase matching and cavity resonance by controlling only the temperature of the crystal. We observe up to -8.0±0.2 dB of squeezing with the bandwidth of 142 MHz. Our technique makes it possible to drive many monolithic cavities simultaneously by a single laser. Hence our monolithic optical parametric oscillator is quite suitable to continuous-variable quantum information experiments where we need a large number of highly squeezed light beams.

Giampiero V. M. Esposito, Giuseppe Marmo, George Sudarshan

Naoto Takanashi, Wataru Inokuchi, Takahiro Serikawa +1 more

We report generation and measurement of a squeezed vacuum from a semi-monolithic Fabry-Pérot optical parametric oscillator (OPO) up to 100 MHz at 1550 nm. The output coupler of the OPO is a flat surface of a nonlinear crystal with partially reflecting coating, which enables direct coupling with waveguide modules. Using the OPO, we observed 6.2dB of squeezing at 2 MHz and 3.0 dB of squeezing at 100 MHz. The OPO operates at the optimal wavelength to minimize propagation losses in silica waveguides and looks towards solving a bottleneck of downsizing these experiments: that of coupling between a squeezer and a waveguide.

Pedro Enrique Piñeros Lourenço

Gerd Breitenbach, T. Müller, Silvania F. Pereira +3 more

We have developed a stable, reliable source of continuous-wave squeezed vacuum at 1064 nm, using a subthreshold monolithic lithium niobate optical parametric oscillator. Quantum-noise reduction below the vacuum noise level in a bandwidth of 30 MHz with a maximum of 5.5 ± 0.2 dB at 2 MHz is demonstrated. The reconstruction of the Wigner function of a continuous-wave, strongly squeezed-vacuum state is obtained.