以瓦級輸出的光參振盪器運用在波形合成的研究上，而波形合成需要將光參振盪器輸出頻率控制在一比三的關係上。若光參振盪器輸出頻率存在頻率變動量時，導致頻率不為一比三關係，則電場合成出的波形會產生變形，因此需要一套有效的回授系統，來控制光參振盪器的頻率輸出，將頻率變動量控制得越小越好。
內文首先提到光參振盪器及穩頻運用的發展，接著簡介實驗上所運用的原理。並將實驗架構，分為兩大部分做介紹：光參振盪器及回授迴路。最後列出在回授控制之前，對於使用的光源及元件，進行測試以了解其頻率變化特性。而依據這些測試結果，提供適當的回饋去調控整個系統，並呈現出測試結果及經回授後的頻率變化。
目前實驗結果，回授系統可將頻率變動量控制在小於1.4 MHz以內，且從光參振盪器輸出的閒置光及訊號光的功率，分別為1.6 W及1.2 W。之後，改善幫浦光的頻率穩定度及回授控制的反應速度，並改進實驗架構將頻率控制得更穩定，以縮小頻率變動量。

This research focuses on the development of a feedback system that provides effective control of the output frequency of a frequency divide-by-three optical parametric oscillator (OPO). This work will facilitate the use of the OPO to ultrafast waveform synthesis. Simulation shows that if the idler frequency of a divide-by-three OPO has an offset of Δω from exactly one-third of the pump frequency waveforms synthesized with this OPO output will be distorted periodically because the frequencies are not commensurate. Therefore, we need an effective feedback system to minimize Δω and stabilize the output frequencies of the OPO.
The first part of this thesis is an introduction to the OPO and the past development of frequency stabilization techniques. Then the basic principle of the scheme used in controlling a divide-by-three OPO output frequency is described. The third part of the thesis provides details of the OPO setup and the feedback system used in this project. Results of measurements performed on the free-running OPO to characterize its frequency fluctuation and tests on the feedback electronics to ensure that they function as expected are then presented. The test results are used to set the electronic and optical parameters for controlling the frequency drift/fluctuation to achieve a minimum offset for the divide-by-three objective and are described in the next and final section.
At this moment the OPO can be locked to operate so that the one-standard deviation fluctuation around zero offset frequency is less than 1.4 MHz. The output power of the idler and signal is 1.6 W and 1.2 W, respectively. The offset frequency fluctuation can be reduced further in the future by improving the response of the electronic feedback circuit and the stability of the OPO.

[1]http://www.phy.ncu.edu.tw/notes/down/laser/extra.htm
[2]http://ejournal.stpi.narl.org.tw/NSC_INDEX/Journal/EJ0001/9905/9905-10.pdf
[3]T. H. Maiman, “Stimulated Optical Emission in Ruby,” J. Opt. Soc. Am., 50, 1134, 1960.
[4]P. A. Franken, G. Weinreich, C. W. Peters, and A. E. Hill, “Generation of Optical Harmonics,” Phys. Rev. Lett., 7, 118, 1961.
[5]J. A. Armstrong, N. Bloembergen, J. Ducuing, and P. S. Pershan, “Interactions between Light Waves in a Nonlinear Dielectric,” Phys. Rev., 127, 1918, 1962.
[6]J. A. Giordmaine and R. C. Miller, “Tunable coherent parametric oscillation in LiNbO3 at optical frequencies”, Phys. Rev. Lett., 14, 973, 1965.
[7]A. Henderson and R. Stafford, “Low threshold, singly-resonant CW OPO pumped by an all-fiber pump source,” Opt. Express, 14, 767, 2006.
[8]H. C. Chen, C. Y. Hsiao, W. J. Ting, S. T. Lin, and J. T. Shy, “Saturation spectroscopy of CO2 and frequency stabilization of an optical parametric oscillator at 2.77 μm,” Opt. Lett., 12, 2409, 2012.
[9]J. Ng, A. H. Kung, A. Miklos, and P. Hess, “Sensitive wavelength-modulated photoacoustic spectroscopy with a pulsed optical parametric oscillator,” Opt. Lett., 29, 1206, 2004.
[10]R. W. P. Drever, J. L. Hall et al., “Laser phase and frequency stabilization using an optical resonator,” Appl. Phys. B, 31, 97, 1983.
[11]A. Cygan, D. Lisak, P. Masłowski et al., “Pound-Drever-Hall-locked, frequency-stabilized cavity ring-down spectrometer,” Rev. Sci. Instr., 82, 063107, 2011.
[12]V. N. Baryshev , “Laser frequency stabilisation by the Pound-Drever- Hall method using an acousto-optic phase modulator operating in the pure Raman-Nath diffraction regime, ” Quant. Elect., 42, 315, 2012.
[13]D. J. Jones, S. A. Diddams, J. K. Ranka, A. Stentz, R. S. Windeler, J. L. Hall, and S. T. Cundiff, “Carrier-envelope phase control of femtosecond mode-locked lasers and direct optical frequency synthesis,” Science, 288, 635, 2000.
[14]L. N. Langley, M. D. Elkin, C. Edge et al., “Packaged semiconductor laser optical phase-locked loop (OPLL) for photonic generation, processing and transmission of microwave signals,” IEEE Trans. Microwave Theory Tech., 47, 1257, 1999.
[15]A. Ramaswamy, L.A. Johansson, J. Klamkin et al., “Coherent receiver based on a broadband optical phase-lock loop,” National Fiber Optic Engineers Conference (NFOEC), Anaheim, CA, 2007.
[16]H. S. Chan, Z. M. Hsieh, W. H. Liang, A. H. Kung, C. K. Lee, C. J. Lai, R. P. Pan, and L. H. Peng, “Synthesis and measurement of ultrafast waveforms from five discrete optical harmonics,” Science, 331, 1165, 2011.
[17]D. H. Lee, M. E. Klein, J. P. Meyn, and R. Wallenstein, “Phase-coherent all-optical frequency division by three,” Phys. Rev. A, 67, 013808, 2003.
[18]A. Douillet, J. J. Zondy, G. Santarelli, A. Makdissi, and A. Clairon, “A phase-locked frequency divide-by-3 optical parametric oscillator,” IEEE Tran. Instr. and Meas., 50, 548, 2001.
[19]http://www.rp-photonics.com/optical_parametric_oscillators.html
[20]B. E. A. Saleh and M. C. Teich, “Fundamentals of Photonics”, 2nd WILEY, 2007
[21]R. W. Boyd, “Nonlinear Optics”, 2nd ACADEMIC PRESS, 2003.
[22]http://www.rp-photonics.com/optical_resonators.html
[23]R. E. Best, “Phase-locked loops theory, design, and applications,” 6th Ed. McGraw-Hill, 2007.
[24]楊琇茹,“適用於光學頻率梳的光學鎖相迴路,” 大專學生參與專題研究計畫研究成果報告, 2011.
[25]http://tds.ic.polyu.edu.hk/mtu/atm/pid/t1/p2.htm
[26]http://en.wikipedia.org/wiki/PID_controller
[27]http://radhesh.wordpress.com/2008/05/11/pid-controller-simplified/
[28]B. Borchers, S. Koke, A. Husakou, A. Herrmann, and G. Steinmeyer, “Carrier-envelope phase stabilization with sub-10 as residual timing jitter”, Opt. Lett., 36, 4146, 2011.