EXTERNAL RESONATOR VARIABLE WAVELENGTH LASER AND ITS PACKAGING METHOD

摘要

A semiconductor optical amplifier (1) has an end face reflectivity of at most 0.1% on the side constituting an external resonator, and the value of the finess determined by obtained by dividing the period of the transmission characteristics of a wavelength selection filter (3) by the half-peak value of the transmission characteristic is in the range of 4-25. Even when the reflectivity on the resonator side end face (1bb) of the semiconductor optical amplifier (1) is about 0.1%, the wavelength precision of about ±1.5 GHz can be achieved by setting the finess at 4 or above. The wavelength precision of about ±0.5 GHz can be achieved by setting the finess at 8 or above. In order to suppress insertion loss, the finess of an FP etalon is preferably set at 25 or less. Consequently, an external resonator variable wavelength laser having high wavelength precision can be realized.