EXTERNAL RESONATOR TYPE WAVELENGTH-VARIABLE LASER DEVICE

摘要

It is possible to realize an external resonator type wavelength-variable laser device which can preferably exhibit a wavelength varying function even by using a planar wavelength-variable reflection structure having a significant residual reflection. The external resonator type wavelength-variable laser device includes a planar reflection structure which can vary a reflection spectrum peak wavelength and a semiconductor element as a semiconductor gain medium. The semiconductor gain medium is formed by a multi-quantum well in which the product G·L of the light confinement constant G of the gain layer and the semiconductor gain medium length L (µm ) is in a range not smaller than 25 µm and not greater than 40 µm; and the gain peak wavelength ?0 (nm) upon implantation of carrier density having the maximum mode gain equal to an internal loss of the semiconductor gain medium is in a range greater than -3 x ?R/2 + (?c + 35) and smaller than (- (G·L)/7 + 8) x ?R + (- (G·L) + ?c + 45), wherein ?R (dB) is a reflection ratio difference and ?c (nm) is a central wavelength of the operation wavelength range of the wavelength-variable laser device.