Products - Gain-modules (GM)

The Gain-Module is a similar device to the Gain-Chip, but has one side coupled into single mode fiber. It is greatly applicable for building tunable lasers with a fiber output. Factory made fiber coupling ensures optimized coupling efficiency, long-term stability and excellent reliability. The Gain-Module eliminates the need for a number of components typically used in schemes with a bare Gain-Chip, thus substantially improving system reliability and reducing costs. A further feature of the Gain-module is temperature stability due to the built-in TEC and a high precision thermistor.

The device comprises a Gain-chip of "Type C" with a curved stripe. The facet where the stripe is tilted is designed for external feedback and features deep AR coating, resulting in extremely low back-reflection to the chip waveguide. It ensures the blocking of self-lasing and as well eliminates issues related to the compound cavity when operating in the external cavity system. This results in a very fine spectral line with high Side-Mode Suppression Ratio (SMSR) inherent across the full tuning range. The facet with a perpendicular stripe has the appropriate reflection (typically in the range of 5-15%) to simultaneously provide broad wavelength tuning with high output power. Reflection of this facet in a standard device is optimized for operation in an external cavity setup which provides efficient feedback (about 50%) to the chip (schematically shown in the picture). For schemes with lower feedback, we would recommend a customized device with a different coating on the facet to provide optimized reflection.

Tips for designing the external cavity:

• it is recommended to use a blazed grating in order to minimize loss to other reflection orders;
• in case of a grating with higher efficiency in polarization orthogonal to grooves, it is recommended to use λ/2 plate for the combination of high wavelength resolution with the best reflection efficiency.

Note: The operating wavelength, facet reflection and other parameters can be optimized for a particular application and design of external cavity system. Our knowledgeable Application Team is ready to consult and advise on the optimal solution based on your needs and application. Please, for a customized solution.