| 摘要 |
PURPOSE:To expand a tunable wavelength range, by arranging an acoustooptic element, which interferes with an incident laser beam for exciting sound waves, at a position, to which the laser beam from a semiconductor laser is inputted, at the outside of the semiconductor laser. CONSTITUTION:A laser beam from a main body 11 of a semiconductor laser is inputted in an acoustooptic element 13 through a collimating lens 12. An electroacoustic transducer element 14 and a high frequency power source 15 for exciting a suitable sound wave for the acoustooptic element 13 are provided. The main body 11 of the laser can be arbitrarily formed, but it is desirable to attach a reflection preventing film on the surface facing the lens 12. As a principle, a sound wave having a suitable wavelength and an intensity is formed in the acoustooptic element (TeO2) 13 through the electroacoustic transducer 14, and DFB (distribution feedback) action is imparted to the sound wave. Thus the oscillating wavelength of the semiconductor laser can be varied in a broad range only by the electric signal. The variable range reaches the intrinsic gain width (about 10 TH2) of the semiconductor laser and can be made as large as two orders of magnitude that of a conventional current injection type DFB laser.
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