Theoretical And Experimental Study On Preparation And Detection Of Squeezed States Of Light At1064nm

The basic physical obstacle that affects detection accuracy and image quality is theshot noise limit and diffraction limit in classical optics. Quantum noise representssome minimum unavoidable fluctuations in the intensity, it forms the quantum noiselimit, or QNL, for the intensity noise, which arises from an intrinsic property of thequantization of the light. Both in military and civil applications call for more stringentrequirements to the detection accuracy and image quality, especially for applicationsin faint luminescence, in which the quantum fluctuations become the fundamentallimit to detection and imaging as the light intensity is reduced continuously. As aresult, researchers began looking for non-classical light states with quantum noisebelow the standard quantum noise limit and squeezed light become the best candidateas one of the quadratures has reduced quantum fluctuations.Squeezed light not only can be used as an independent non-classical light sourcefor optical precision, atomic spectroscopy and gravitational wave detection, but alsocan be used as an important resource for entangled light, which is also a kind ofnon-classical light. Based on this, this paper focus on the theoretical and experimentalstudy on preparation and detection of squeezed states of light at1064nm and the mainresearch works and innovations of this dissertation are summarized as follows:Firstly, a comprehensive analysis of the theoretical and experimental basis of theproduction of squeezed light is given. We focus on the generation of the squeezedlight with nonlinear optical parametric process in an optical parametric amplifier(OPA) and analyze various elements that affect the increasing of squeezing degree bynumerical simulation. The impact of every parameter on squeezing level is measuredby controlling other parameters under a variety of conditions. The theoretical resultsshow that the degree of squeezing decreases linearly with the increase of intra-cavityloss and the effect of normalized pump power on the squeezing level is greater thanthat on the anti-squeezing level under experimental conditions. In addition, therelative phase fluctuations in homodyne detection and low mode matching efficiencyare important limiting factors for the observed squeezing degree. Secondly, to improve the mode matching efficiency, we analyze the elements thatcaused the mismatching of the cavity theoretically and the theoretical parameters forperfect mode matching are given. The mode matching between the laser light and theeigen mode of the cavity is improved by optimizing the system and the desired modeof the cavities can be derived, including the OPA, the mode cleaning cavity and theF-P cavity. Ideally, the highest degree of í8.75dB would be obtained if the modematching efficiency is closed to1, with the same experimental parameters for the rest.The theoretical and experimental results show that it is essential to optimize the modematching efficiency to generate and detect stable and high degree of squeezing.Thirdly, quadrature amplitude squeezed light is generated by utilizing thedegenerate OPA based on type I periodically poled KTiOPO4(PPKTP) crystal. aside-of-fringe locking technique is applied to achieve the resonance between the OPOcavity and the injected laser beam and the locking time is no less than2h. The highestsqueezing level is í5.5dB for instantaneous measurement and decreased to í3.8dBfor long time measurement as a result of pump noise and the relative phasefluctuations in homodyne detection. The squeezed light is applied to imaging of acharacter-plate. The experimental results indicate that the obtained image quality issuperior to that obtained by infrared coherent light. To explain the relations betweenthe signal-to-noise ratio (SNR) in detection and the observed squeezing degreeexplicitly, we take the applications of the squeezed light in frequency modulation (FM)saturation spectroscopy in atomic cesium as an example, the relations between theSNR and the squeezing degree are investigated and the theoretical results show thatthe SNR increased rapidly with the increase of the squeezing level.Finally, based on the studies of the single mode squeezed light, the theoreticalanalysis and experiment scheme of the spatial multi-mode squeezed states of light aregiven. In the experiment scheme, higher order mode squeezed light is generated byflipping fundamental mode squeezed light.