| A single narrow line width tunable external cavity feedback semiconductor used in frequency doubling blue light is proposed. It is constructed with laser base, laser tube, collimation system, and optical grating. Via the current and temperature control, It is selected the mode of semiconductor laser used in the feedback of grating. The structure of external cavity makes the spectral line width of output light to be narrowed. Thus a single longitudinal mode, narrow spectral line width and stable frequency external cavity semiconductor laser is realized, and its spectral line width is compressed to be less than 1MHz. Precision temperature control circuit use PID control and Ziegler-Nichols setting regulation to set the PID circuit parameters. Finally it realize the temperature control of long-range,fast-response and high-stability to semiconductor laser, assure the veracity of temperature control, minish the error. |
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