| 摘要 |
PURPOSE: To enable a variable wavelength semiconductor laser to be widened in an operating temperature range by a method wherein the wavelength of light which an active layer is capable of oscillating is set coincident with that of light determined by the period and refraction index of a diffraction grating at a lower temperature than a room temperature. CONSTITUTION: The gain peak wavelength of a GaAs active layer 5 is as long as 822nm, the periodΛof a diffraction grating 8 is so determined as to set a reflection wavelengthλof a DBR region 3 determined by a formula,λ=2nDBRΛ, to 822nm, and a semiconductor laser of this constitution oscillates in wavelength of 822nm at a temperature of 77K. At this point, nDBR denotes the refractive index of the DBR region 3. A change of the DBR region 3 in the reflection wavelengthλwith a temperature change is almost equal to 0.06nm/1K or so, and the wavelengthλof the DBR region 3 becomes 835nm at a room temperature. When the DBR region 3 is increased in temperature to change oscillation light in wavelength, an operating temperature range of the DBR region 3 is as large as 322K even if the maximum temperature of the DBR region 3 is 400K as usual. Therefore, the variable wavelength range of a semiconductor laser of this constitution is 19nm or so wide, so that the semiconductor laser is markedly improved as compared with a conventional one whose variable wavelength range is 6nm wide.
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