Classical And Quantum Properties Of A Singly Resonant Optical Parametric Oscillator

Near-and mid-infrared classical and quantum lasers have important applications in high-resolution spectral analysis,atmospheric pollution monitoring,life sciences,quantum communication and quantum precision measurement.In order to meet the needs of near-and mid-infrared lasers in these fields,the experimental and theoretical research of the classical and quantum properties of a singly resonant optical parametric oscillator(SRO)are studied in this paper.The main contents are as follows:(1)The wavelength tuning and output characteristics of signal and idler generated by stand-wave cavity and ring cavity SRO are studied.First,the stand-wave cavity and ring cavity SRO are designed according to the theoretical calculations,and change the poling period and temperature of the PPLN crystal,the output signal and idler of two SRO can be tuned from 1.4?m to 1.7 ?m and from 3.9 ?m to 2.6 ?m,respectively.Then the output characteristics of signal and idler were studied.The pump threshold power of stand-wave cavity SRO is 3 W,when the pump power is 15.5 W,the output power of the signal and idler is 5.1 W and 2.1 W(wavelength of signal and idler are 1.522 ?m and 3.533 ?m),respectively,the light-to-light conversion efficiency is 46.5%;the power fluctuations of the signal and idler are better than ± 2.77% and ± 2.79% for a given 4 hours,and the frequency drift of the signal is better than ± 45 MHz for a given 4 hours.The pump threshold power of the ring cavity SRO is 9 W,when the pump power is 25 W,the output power of the signal and idler is 6.9 W and 3.1 W(wavelength of signal and idler are 1.523 ?m and 3.528 ?m),respectively,the light-to-light conversion efficiency is 40%;the power fluctuations of the signal and idler are better than ± 1.75% and ± 1.55% for a given 4 hours,and the frequency drift of the signal is better than ± 43 MHz for a given 4 hours.(2)We propose a wavelength tuning method for SRO with theadvantages of simultaneously mode-hop-free tuning of both signal and idler,wide tuning band and moderate tuning speed.Based on the theoretical analysis,the synchronized feedback control scheme of the intracavity etalon is designed to eliminate the mode hop occurred in the temperature tuning process.Since the temperature control system is optimized with nonlinear variation of the setting temperature,leading to the fast temperature tuning of the nonlinear crystal with a tuning speed of 0.11 ?/s and a tuning range from 20 ? to 70 ? without overshoot and oscillations,continuous mode-hop-free tuning with a bandwidth of 2063.7 GHz and a tuning speed of 4.7 GHz/s for both signal and idler were achieved.The tunable infrared lasers were also used to demonstrate high resolution absorption spectra of acetylene and methane across the mode-hop-free tuning range simultaneously.Finally,the output stability of the SRO under the feedback system is studied.The power fluctuations of the signal(output power is 4.1W,wavelength is 1.558 ?m)and idler(output power is 2.25 W,wavelength is 3.355 ?m)are ± 0.42% and ± 0.18% for a given 1 hour,the frequency drift of the signal is ± 10 MHz for a given 1 hour.(3)Theoretical and experimental research on the intensity noise characteristics of signal and idler.Through experimental and theoretical calculations,it was found that when the temperature of MgO: PPLN crystal and the modulation frequency of the modulation signal applied to the intracavity etalon are increased,the intensity noise of the signal and idler showed a downward trend.The intensity noise of the signal and idler reaches the shot noise level in the range of analysis frequencies greater than 5.5MHz and 4 MHz,respectively.At the analysis frequency of 300 kHz,there is a relaxation oscillation noise much larger than the shot noise level.By controlling the temperature of MgO: PPLN crystal to 60 ? and the modulation frequency of the feedback control etalon to 8 kHz,the intensity noise of the signal and idler is reduced by 11 dB and 8 dB at the analysis frequency of 300 kHz.(4)The SRO was used to obtain a two-color continuous variablequantum correlation between 1.5 ?m and 3.3 ?m.First,the semi-classical theory was used to calculate the intensity difference noise spectrum of the signal and idler,and the change of the intensity difference noise spectral with the pump parameter and analysis frequency are studied.The pump threshold power of SRO is 7.3 W,when the pump power is 15.5 W,the output power of the signal and idler is 10 mW and 2.1 mW,respectively,the measurement of quantum correlation between 1.5 ?m and 3.3 ?m is 1.8 dB.Through theoretical and experimental research,it was found that when the analysis frequency is changing from 5 MHz to 11 MHz and below 5 MHz,the quantum correlation between 1.5 ?m and 3.3 ?m gradually decreases,and the quantum correlation between 1.5 ?m and 3.3 ?m is highest when the pump power close to the threshold,and it will gradually decrease after increasing the pump power.The innovative works of this thesis are as follows:(1)We propose a wavelength tuning method for SRO with the advantages of simultaneously mode-hop-free tuning of both signal and idler,wide tuning band and moderate tuning speed.Through the synchronized feedback control scheme of intracavity etalon and the temperature control system which was improved by using the combination of Labview and data acquisition card with the temperature controller.The signal and idler can be continuously mode-hop-free tuned 2063.7 GHz,and the tuning speed is 4.7GHz/s.(2)The factors that reduce the intensity noise of signal and idler are studied.By controlling the MgO: PPLN crystal temperature to 60 ? and the modulation frequency of the feedback control etalon to 8 kHz,the intensity noise of the signal and idler is reduced by 11 dB and 8 dB at the analysis frequency of 300 kHz.(3)The SRO was used to obtain the two-color continuous variable quantum correlation between 1.5 ?m and 3.3 ?m for the first time.By controlling the pump parameter,the quantum correlation between 1.5 ?m and 3.3 ?m obtained is 1.8 dB at the analysis frequency of 5 MHz.