PURPOSE: To realize frequency stability even in a long wavelength band by a method wherein a light from a semiconductor light-emitting element is made to branch into an output light and a light to be detected, the latter is transformed into a transformed wavelength light of a shorter wave length, a change in the wavelength of the transformed light is detected and a control is made on the basis of a detection output so that an oscillation wavelength of the element be a prescribed one.
CONSTITUTION: A semiconductor laser 1 as a light source outputs a laser light L0, which is made to branch into a stabilized output light L1 and a light L2 to be detected, by a half mirror MM. The light L2 to be detected is inputted to a wavelength transformation element 2 and it is turned thereby into a transformed wavelength light L3 of a wavelength of 1/2 and made to enter a wavelength change detector 3. The detector 3 can be constructed of a hollow cathode lamp utilizing a photo-galvanic effect and can convert a minute change in the wavelength into an electric change. This detection output is given to a drive current source 5 through the intermediary of a detecting element 4, a negative feedback is applied to a drive current of the semiconductor laser 1, and an oscillation wavelength can be controlled by controlling the drive current. A temperature control element 6 controls the temperature of the semiconductor laser 1. By the above constitution, high frequency stability can be realized.
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KOISHI YU
MASUDA NAOKI
AKAI YOSHIRO
| JPS63137494A | 1988-06-09 | |||
| JPH01102978A | 1989-04-20 |