Twisted double-heterostructure GaAs-(AlGa)As laser

A novel laser structure in which a channeled substrate laser is connected to a terraced substrate laser is fabricated. The active layer of the composite cavity is twisted in the junction area between the two laser cavities. A built-in refractive index variation is provided in both terraced substrate and channeled substrate cavities. A low threshold current of 40 mA is obtained in the twisted double-heterostructure(TDH) laser with a single twisted region, which shows a single-longitudinal-mode oscillation in addition to a stable fundamental-transverse-mode oscillation. Polarization change and interferometric effect caused by internal reflection in the twisted region are observed. A multiple twisted double-heterostructure(MTDH) laser is also fabricated by connecting a terraced substrate laser and a channeled substrate laser alternately. The MTDH laser with two twisted regions shows wavelength locking over a temperature range of more than 25°C within which the wavelength changes at a rate of 0.6 Å/°C.