Theoretical And Experimental Investigation Of All-solid-state CW Single-frequency Lasers And Non-classical Optical Fields At Telecommunication Wavelength

The continuous variable?CV?non-classical light fields at the optical communication wavelengths,such as 1.34?m and 1.5?m are the fundamental resources for the researches on quantum optics and practical CV quantum communication,due to their low phase diffusion effect or low transmission loss when passing through an optical fiber.In order to generate a high quality CV quantum entanglement at 1.34?m,a high power continuous wave?CW?single frequency laser source at 1.34?m and 671 nm should be developed.However,comparing with the 1.06?m laser,the energy transfer upconversion?ETU?and excited state absorption?ESA?effects significantly influence the output characteristics of the 1.34?m laser,and the laser power was less than 10 W so far.In the field of quantum information,the multi-component quantum entanglement generated by pumping multiple optical parametric oscillators is strongly desired to build the quantum information networks.When the scale of the entanglement is going to be enlarged,there will be a challenge to the output power of 1.34?m lasers.In this thesis,the CW single-frequency laser at 1.34?m with high power and low noise were experimentally and theoretically investigated in detail.In addition,the continuous variable EPR quantum entanglement at a telecommunication wavelength of 1.34?m was experimentally generated by using a nondegenerate optical parametric amplifier?NOPA?,and a bright amplitude quadrature squeezed light for continuous variable at telecommunication wavelength of 1.5?m from degenerate parametric amplifier?DOPA?was also experimentally generated.The main contents are as follows:?1?A CW single transverse mode 1.34?m laser with the output power of 16 W was developed.Firstly,a self-consistent theoretical model considering both energy-transfer upconversion?ETU?and excited-state absorption?ESA?effects was developed to simulate the behaviors of diode-end-pumped CW single-transverse-mode(TEM₀₀)lasers.Then,the iterative method was used to deal with the couplings among the temperature distribution in the laser crystal,the thermal fractional loading,the upper state population involved in the ETU and ESA effects,the laser output and other temperature-dependent parameters.In the experiment,based on the dual-end pumping scheme,decreasing the boundary temperature of the crystal and optimizing the transmission of the output coupler,the laser performance was increased.Finally,a high power CW TEM₀₀ Nd:YVO₄ 1.34?m laser was achieved with a maximum output power of 16 W.The measured power stability was better than±0.9%in a given four hours.The theoretical predictions considering both ETU and ESA effects are in good agreement with experimental results.?2?An all-solid-state CW single frequency 1.34?m Nd:YVO₄ laser with a maximum power of 11.3 W was developed.Firstly,a universal model about the sufficient physical conditions of single frequency operation was established by considering the relationship between the gain difference and the nonlinear loss difference by introducing the nonlinear loss in the resonant cavity.In the experiment,an all-solid-state CW single frequency1.34?m Nd:YVO₄ laser with a maximum power of 11.3 W at 1.34?m and0.3 W at 671 nm was developed.The laser can be single frequency operated stably and mode-hop-free.The measured power and frequency stability were better than±0.5%and±88 MHz in a given three hours.The intensity noise reached the shot noise limite?SNL?at the analysis frequency of 2.5 MHz.The experimental results are in good agreement with the results of theoretical simulation and analysis.?3?Based on the polarized and dual end pimping scheme,an all-solid-state high power,low noise and CW single frequency 671 nm/1.34?m dual wavelength laser by directly pumped at 880 nm was developed.The astigmatism of the laser resonator was eliminated by the resonator design,and the mode matching between the oscillating and the pump laser was improved.The maximum output power of the single frequency 671 nm and1.34?m laser were 3.17 W and 2.15 W,respectively.The intensity and phase noise of the 671 nm and 1.34?m laser all reached the SNL at the analysis frequency of 3 MHz.?4?The continuous variable EPR quantum entanglement at a telecommunication wavelength of 1.34?m was experimentally generated by using a nondegenerate optical parametric amplifier?NOPA?with a type-II periodically poled KTiOPO₄?PPKTP?,in which the self-made high-power,low noise CW single frequency 671 nm/1.34?m dual wavelength laser was used as the pump source of the NOPA.The quantum correlations of the amplitude and phase quadratures between the signal and idler beams produced from the double resonant NOPA were all 3 dB.Furthermore,the principle of quantum entanglement generated from the parametric down-conversion of the NOPA,and the detection scheme of the quantum entanglement were theoretically analyzed.?5?A telecommunication wavelength bright amplitude quadrature squeezed light for continuous variable at 1.5?m from a semi-monolithic degenerate parametric amplifier?DOPA?based on a periodically poled KTP crystal was demonstrated by using a commercial single frequency 1.5?m fiber laser as the laser source.The pump field at 780 nm of the DOPA was obtained by external cavity frequency-doubling process.In order to reduce the intensity noise of the laser,the mode cleaners were used.Finally,3 dB bright amplitude quadrature squeezed light was experimentally obtained.Besides,the principle of bright amplitude quadrature squeezed light generated from the DOPA with injected signal light was theoretically analyzed.The innovative works of this thesis are as follows:?1?A self-consistent theoretical model considering both ETU and ESA effects was developed for the first time to simulate the behaviors of diode-end-pumped CW TEM₀₀ 1.34?m lasers,in which the iterative method was used to deal with the couplings among the temperature distribution in the laser crystal,the thermal fractional loading,the upper state population involved in the ETU and ESA effects,the laser output and other temperature-dependent parameters.Based on the dual-end pumping scheme,decreasing the boundary temperature of the crystal and optimizing the transmission of the output coupler,a high power CW TEM₀₀ Nd:YVO₄ 1.34?m laser was achieved with the output power of 16 W.The theoretical predictions considering both ETU and ESA effects are in good agreement with experimental results.?2?A universal model about the sufficient physical conditions of single frequency operation was established by considering the relationship between the gain difference and the nonlinear loss difference by introducing the nonlinear loss in the resonant cavity for the first time.Based on the polarized and dual-end-pimping scheme,an all-solid-state CW single frequency 1.34?m Nd:YVO₄ laser with a maximum power of 11.3 W at 1.34?m and 0.3 W at 671 nm was developed.The laser can be single frequency operated stably and mode-hop-free.?3?The continuous variable EPR quantum entanglement at a telecommunication wavelength of 1.34?m was experimentally generated by using the self-made high-power,low noise CW single frequency 671nm/1.34?m dual wavelength laser.The quantum correlations of the amplitude and phase quadratures between the signal and idler beams produced from the double resonant NOPA were all 3 dB.?4?A telecommunication wavelength bright amplitude quadrature squeezed light for continuous variable at 1.5?m with the squeezing level of-3 dB was experimentally generated for the first time by using a commercial single frequency 1.5?m fiber laser as the laser source.