Gain Crystals for Yellow Lasers.

Photography by Marieke Lienert

MEmbrane eXternal cavity Laser (MEXL) crystals enable simple and compact laser modules emitting visible light, especially in the yellow spectral range. The MEXL gain crystal is based on a µm-thin semiconductor membrane sandwiched between two optically transparent heat spreaders. By altering the material composition, the laser emission wavelength is adjusted during the fabrication process. All production steps are performed on the wafer-level ensuring consistently high quality and offering the potential for high-volume fabrication.

Excellent Beam Quality. Watt-Level.

Combined with an outcoupling mirror and an optical pump source, the MEXL gain crystal delivers Watt-level continuous-wave output powers with diffraction-limited beam profile. The external cavity also provides space for SHG crystals to exploit the high intra-cavity power, which allows efficient frequency doubling from the near-infrared to the green-yellow spectral range.

No Pump Optics. Simple.

Photography by Marieke Lienert

However, compared to conventional laser crystals, the short upper-state lifetime in the semiconductor material inherently results in low-noise operation and high-contrast modulation capabilities up to MHz frequencies. Due to the absorption properties of the semiconductor membrane, there is no need for focusing optics or stabilization of the pump source to a fixed wavelength. Thus, the MEXL technology opens the possibility to realize compact yellow laser modules in a simple way.