High-power frequency stabilized tapered diode amplifiers at 1064 nm

The realization of a compact green-emitting solid state laser source for applications like laser TV or head-up displays is still a challenging task. One way to generate green light with a solid state laser source is nonlinear frequency upconversion (frequency-doubling) of e. g. 1064 nm to 532 nm. In order to achieve good conversion efficiencies tunable laser sources with output powers of several watts, narrow bandwidth and good beam quality are required. We have realized tapered laser diodes based on the GaInAs/AlGaAs material system emitting at a central wavelength of 1064 nm. These devices have an AR-coating on the front facet as well as on the ridge facet. Therefore, these laser diodes can be frequency stabilized in an external cavity setup consisting either of a grating in Littrow mounting placed on the rear side or by an integrated Fiber Bragg grating. The latter configuration allows a compact low footprint integration of the laser diodes into compact laser modules. The optical output power of these devices frequency stabilized at 1064 nm exceeds 4 W with beam qualities suitable for frequency doubling (M-2 < 2) and a tuning range from 1030 nm to 1070 nm. For laser diodes with a HR coating on the ridge facet even higher output powers of more than 8 W are achieved. The ridge and tapered section of the tapered diode amplifiers are contacted separately in order to enable the modulation of the light source by the variation of the ridge current. The rapid temporal modulation achieved this way is a prerequisite for the use of such lasers in flying spot display applications.