LD End-pumped Nd: YVO₄/LBO Single-Frequency Laser At 671nm

Diode-pumped solid-state lasers(DPSL), with high efficiency, nicebeam quality, compact configuration, and long lifetime, have beenextensively applied in military affairs, medical treatments, scientificresearches, and so on. Especially, the single-frequency DPSL are required fora lot of applications such as spectroscopy, coherent measurement andholography. Along with the development of crystal growing technology andLD technology, all-solid-state red lasers have shown broad potentialapplications in color displays, biomedical, and pumping sources for tunableCr:LiSAF lasers. Since the wavelength of 1.3μm is the transmission windowof silicon fiber, the lasers at 1.3μm are very important for the opticalcommunication in fibers. With the single-frequency red laser at 671nm to bethe pump source, the entangled light at 1342nm can be obtained via theprocess of frequency-down-conversion. The entangled optical beam at1342nm is a basic resource for the practical application of quantuminformation. Thus, the single-frequency lasers at 671nm are also thenecessary pump sources for developing quantum communication in opticalfibers.In this thesis, the experimental and theoretical study on laser-diodeend-pumped CW Nd:YVO₄/LBO single-frequency red laser at 671nm withintracavity frequency-doubling is presented. The laser was end-driven by alaser diode. A type-Ⅰcritical phase-matched LBO crystal, a TGG and aλ/2wave plate are placed inside the ring resonator with four cavity mirrors to bethe frequency-doubling crystal and the optical diode, respectively. Thesingle-frequency second harmonic wave output of 360 mW at 671nmwavelength with the longtime intensity fluctuation less than 1.0% within 1hour was obtained. At the same time the frequency shift of the fundamentalwave at 1342nm of less than±4.7MHz(1 minute) was observed. The thesis consists of the following four chapters:Chapter 1: IntroductionIn this part, the progressing history and developing tendency of DPSLare reviewed and the research achievements of red solid-state lasersup-to-date are summarized.Chapter 2: The theoretical analysis of second harmonic generation viaintracavity frequency-doubling of LBOThe principle of the frequency-doubled red laser is theoreticallyanalyzed in which the dependence of the frequency-doubling efficiency onthe phase-matching is described. By comparing the non-critical and criticalphase matching in type-Ⅰand type-Ⅱcut crystals, the walk-off effect intype-Ⅰcritical phase matching is discussed. Based on these theoreticalanalysis we drew a conclusion that type-Ⅰcritical phase matching LBOshould be the best candidate for performing the frequency-doubling from1342nm to 671nm.Chapter 3: Design and realization of the laser systemUsing the rate-equation of four-level system, the expressions ofthreshold pump power, output power and slope efficiency are concluded. Inaddition, the effects of parameters of the laser resonators and the thermaleffect of laser crystal are discussed. All above calculated results provided thereliable references for the optimized design of the laser system. Finally,through experimental study we built a LD end-pumped Nd:YVO₄/LBOintracavity frequency-doubled single-frequency red laser, and obtained thestable output power of 360mW at the wavelength of 671 nm.Chapter 4: Conclusion and outlook...