Wafer design of widely tunable vertical-external-cavity surface-emitting laser with broadband gain spectrum
The wafer design of a widely tunable InGaAs/GaAs quantum wells vertical-external-cavity surface-emitting laser (VECSEL) at 1,064nm was presented. A GaAs/AlAs based double-band mirror (DBM) was employed to yield sufficient reflectivity (\(>\)0.999) over 118nm wavelength coverage, which is 54nm wider than that of a usually used distributed Bragg reflector. In the active region, an antiresonant subcavity, formed by the DBM and the air-semiconductor interface, was introduced to produce extended longitudinal confinement factor, and two kinds of InGaAs quantum wells with different In composition were used to expand the material gain. As a result, a broadband gain spectrum of the semiconductor wafer with 85nm FWHM bandwidth was obtained, and this was valuable for broadband performance of a tunable VECSEL.
wafer design tunable vertical-external-cavity surface-emitting laser broadband gain