The Generation Of Squeezed States And Measurement Of Low-frequency Signal

The measurement of low frequency signal is very important in the present optical precision measurements,for example,as one of the most important frontier fields of contemporary physics gravitational wave signal detecting,its detection band is in the acoustic spectrum frequency or even much lower frequency.Since the low frequency squeezed state light field was proposed for quantum noise reductionin interferometric gravitational-wave detection over three decades ago,it has attracted the widespread attention in recent years.Compared with the high-frequency squeezed states,the generation of the low-frequency squeezed states is more difficult,because it is limited by several technical noise sources.In this thesis we report the low-frequency squeezed state light field experimental produced by the parametric process.The squeezed vacuum state phase was controlled using a noise locking technique.Finally,we employed the squeezed vacuum light into a Mach-Zehnder interferometer for the detection of the low frequency signal,an improvement in the signal-to-noise ratio relative to the shot-noise limit has been achieved in the experiment.In this thesis,we mainly investigated the works as following:1.The theoretical investigations of the squeezed states produced in optical parametric process and the queezed states detected on homodyne detection are given.Experimental limitationa of squeezed states generations and homodyne measurements are also investigated.2.The experimental comparison of squeezed states produced in single-resonant optical parametric amplifiers(OPA)and double-resonant optical parametric osillators(OPO)is made.The OPA/OPO is pumped by the light of 532 nm from Nd:YV04/KTP solid-state laser of maximum optical power 3 W.The OPA is seed with a coherent filed at fundamental wavelength(1064 nm)and the OPO is seeded by vacuum fluctuations at 1064nm.3.We use the quantum noise locking technique to enable a stable readout of the squeezed vacuum state on a homodyne detector.4.Utilizing the Mach-Zehnder interferometer to measure the low frequency signal at 90kHz through squeezed vaccuum light is injected into interferometer.the signal-to-noise ratio of 2 dB relative to the SNL has been achieved.