Research On All Solid-State Single Longitudinal Mode 589nm Laser Technology

The all-solid-state compact lasers have the advantages of high efficiency,small size,long life,good beam quality and stable performance,which make them become the focus of laser technology research.With the emergence of nonlinear crystal and its frequency conversion technology,the wavelength range of output light will be further expanded,providing more practical laser wavelengths for laser applications.The intracavity sum frequency single longitudinal mode(SLM)laser studied in this paper is an important research content in the field of solid-state lasers.The low-noise,SLM589 nm laser research can provide reliable and high-quality laser light source for biomedical,sodium laser guiding star,urban observation and scientific research.It can provide theoretical and experimental basis for the development of small visible band,low noise,high stability and frequency laser.Theoretically,the steady state equations for the double wavelength sum frequency oscillating light in the cavity are derived from the double wavelength oscillating rate equation of the four-level system.After the nonlinear crystal is inserted into the cavity,the expressions of sum frequency light and fundamental frequency light are derived by calculating the coupled wave equations of sum frequency light and fundamental frequency light,and the optimal sum frequency efficiency of sum frequency light in the cavity is analyzed.In addition,Jones matrix is used to analyze and demonstrate the principle of frequency selection of sum frequency light.In terms of experiment,the SLM 589 nm yellow light output was achieved by using two resonant cavity structures and frequency selection by birefringent filter.During the study,the longitudinal mode property of the output light was measured by the Fabry-Perot scanning interferometer.In the experiment of direct resonator: 1.The curve of the sum frequency light changing with the pump power and the spectrum of the output laser are measured;2.The longitudinal mode characteristics and the noise of the sum frequency light with or without birefringent filter are compared and analyzed;3.The reason of the noise change of the basic frequency light under different pump power is explained.In the compound cavity experiment: 1.The change curve of the two fundamental and sum frequency light with the pump power and the spectrum of the output light are measured;2.By measuring the noise of the fundamental light under different pump power and the longitudinal mode state of the sum frequency light,the main reason of the noise of the sum frequency light is analyzed.The experimental results show that the source of and frequency optical noise is mainly the noise of the fundamental frequency itself,and using a single birefringent filter to select the frequency of two fundamental frequencies and make them run in a SLM is an effective method to achieve low noise,SLM and frequency lasers.