Abstract
Laser intensity noise suppression has essential effects on preparation and characterization of the audio-frequency squeezed vacuum state of light based on a sub-threshold optical parametric oscillator (OPO). We have implemented two feedback loops by using relevant acousto-optical modulators (AOM) to stabilize the intensity of 795-nm near infrared (NIR) fundamental laser and 397.5-nm ultraviolet (UV) laser generated by cavity-enhanced frequency doubling. Typical peak-to-peak laser intensity fluctuation with a bandwidth of ~10 kHz in a half hour has been improved from ±7.45% to ±0.06% for 795-nm NIR laser beam, and from ±9.04% to ±0.05% for 397.5-nm UV laser beam, respectively. The squeezing level of the squeezed vacuum state at 795 nm prepared by the sub-threshold OPO with a PPKTP crystal has been improved from −3.3 to −4.0 dB around 3~9 kHz of analysis frequency range.
Highlights
The first squeezed vacuum state of light based on an optical parametric oscillator (OPO) was realized by Wu et al [1], since its noise can be lower than the shot noise level (SNL) in a certain quadrature component
At the analysis frequency of MHz, the influence of laser intensity noise upon producing and detecting the squeezed vacuum state of light can be neglected as its background noise is pretty quiet and the SNL can be achieved [9,10,11,12,13]
The squeezed vacuum state of light at audio frequency [14] plays a vital role in certain areas of research, such as gravitational wave detection [2,3,4], magnetic measurements [15,16,17,18,19], and biological measurement [20], whose sensitivity is limited by the squeezing level due to the coupling of low frequency noise
Summary
The first squeezed vacuum state of light based on an optical parametric oscillator (OPO) was realized by Wu et al [1], since its noise can be lower than the shot noise level (SNL) in a certain quadrature component. With the help of the NIR and UV laser’s intensity noise suppression, squeezing level of the squeezed vacuum state of 795-nm light prepared by OPO with a PPKTP crystal is improved from −3.3 to −4.0 dB around 3~9 kHz audio frequency. If the scattering and residual reflection of the lock beam on the surface of nonlinear crystal (PPKTP crystal in our experiment) inside OPO cavity are not considered, OPO runs as an ideal OPO mode for generation of audio-frequency squeezed vacuum state of light. The intensity of pump beam introducing the feedbackwith system important, which can reduce classical noise has close relationships theisaudio-frequency squeezed statenot ofonly light, which brings and can benefit the stable locking of OPO/OPA cavity. Relative intensity noise of LO, which makes it possible for BHD to offset the common-mode noise and easier for us to implement
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
