Experimental Investigation On The Generation Of Squeezed Light At Telecommunication Band Of 1.34?m

All-solid-state continuous-wave single-frequency lasers have the advantages of stable output power,narrow linewidth,excellent frequency characteristics and low noise.So they have been widely applied in important areas,such as laser spectroscopy,cold atomic physics,quantum information and so on.Especially as the pump source for non-classical optical fields,lasers attract attention in terms of power and frequency stability,beam quality and noise characteristics.The squeezed states as important resources of quantum information research,not only can be used for continuous variable quantum information processing,quantum manipulations between fields and atoms interactions,but also can be used for the generation of Einstein-Podolsky-Rosen(EPR)entanglement and the Schr?dinger cat state.Meanwhile the Schr?dinger cat state can be used for quantum teleportation and quantum computation.The purity of the squeezed states is an important factor to limit the generation of the Schr?dinger cat state.Therefore,people have developed relevant researches on the purity of the squeezed states and have made breakthrough progress.Another popular applied area of squeezed states is used to improve the sensitivity of the laser interferometer gravitational wave detector by injecting into the dark port of the detector.It can also be used for low frequency magnetic field measurement and biological particle displacement measurement.The generation of squeezed vacuum states at telecommunication band of 1.34?m is necessary because the optical field will be propagated with lower transmission loss and smaller phase diffusion effect in a Silica fiber.In this paper,the squeezed states at telecommunication band of 1.34?m was generated experimentally.The main contents are as follows:1.A high-power continuous-wave single-frequency low-noise laser with dual-wavelength at 1342 nm and 671 nm was generated.By using the octagonal ring cavity design,the laser with the maximum output power of 1.5W(@671nm)and 1.3W(@1342nm)was obtained by choosing the appropriate laser crystal and nonlinear crystal.The power stability was better than ± 0.6%(4 Hours).The intensity noise and phase noise at 1342 nm both reach the shot noise level at the analysis frequency of 1.7MHz.2.A squeezed vacuum state telecommunication wavelength of 1.34?m was demonstrated from a semi-monolithic optical parametric oscillator(OPO)based on a PPKTP crystal.When the pump power is 20 mW,the squeezed vacuum state with the purity of 0.993 was generated experimentally.The measured squeezing of 2.98 dB with anti-squeezing of 3.04 dB was achieved at the analysis frequency of 1MHz.The low-frequency squeezed states were generated at analysis frequency range from 8kHz-100 kHz with the pump power of 95 mW and the local optical(LO)power of 60?W.A maximum squeeze degree of 5.0dB was obtained at analysis frequency of 36 kHz.A 3.0dB squeezed light was obtained at the lowest audio-band frequency of 8kHz.