The Ferdinand-Braun-Institut (FBH) has developed a very compact laser module with emis-sion at 633 nm. The semiconductor laser module, sized only 76x54x15 mm³, uses a novel butterfly-type housing and aims at replacing bulky HeNe lasers. It offers a flexible platform for the integration of a wide range of photonic components, thus simplifying adaptation for a variety of application scenarios.
The particular module introduced here features an all-semiconductor master-oscillator power-amplifier (MOPA) combined with an iodine gas cell to stabilize the output power as well as the emission wavelength. The MOPA uses newly developed chips, achieving an optical output power of more than 30 mW. A miniaturized optical isolator, purpose-built for the wavelength of 633 nm, is interposed between MO and PA. It features an optical isolation of more than 30 dB and a transmission loss of less than 3 dB. The iodine gas cell is also miniaturized, offering a length of only 30 mm and a clear aperture of 2 mm.
The frequency of the module’s emission could be stabilized by the project partner Toptica to be absolute within a 10 MHz band over a time period of one hour. This corresponds to a frequency stability of 2·10-8, which translates to an accuracy of about 2 microns on a length scale of 100 m. Such accuracy could previously only be reached by large-sized HeNe lasers. The new laser modules will allow a significantly higher degree of miniaturization of interfer-ometric measurement systems in the near future.