Thermoelectric Cooling Solutions

Vertical Cavity Surface Emitting Laser

Vertical Cavity Surface Emitting Laser (VCSEL) — surface-emitting laser with vertical-cavity semiconductor laser diode is a type of emitting the light in the direction perpendicular to the surface of the chip, as opposed to edge-emitting laser diodes, radiating in a plane parallel to the surface.

The main advantages of VCSEL in comparison with traditional edge-emitting semiconductor lasers are small angular divergence and symmetric radiation pattern output optical radiation, temperature and radiation stability, group technology and the ability to test the devices directly on the plate. Planar VCSEL technology allows creating VCSEL arrays - linear arrays and two-dimensional matrices with a large number of individually addressable VCSEL emitters.

VCSEL is used primarily for high rate telecom applications, it refers to the VCSEL structure of GaAs (850 nm) and InP (IR band 1270-2360 nm). In addition the IR VCSEL are used for the purpose of optical  gas analysis. Particularly promising are tunable VCSEL.

In spite of the high temperature stability, however, the emitting power, spectral line of radiation have strong temperature dependency. Therefore, in many of these applications thermostabilization is applied widely to ensure the stability of the operational parameters, as well as for longer lifetime.

Features for thermal management task of VCSEL are the following:

  • Super miniature design of the VCSEL. The VCSEL chips have small size less than one millimeter in the plane. Even in VCSEL arrays total size is only a few mm. Therefore, typically the VCSEL are mounted into miniature package of TO-Can type.
  • Single-chip VCSEL is low power as usual. Output power is maximum tens of mW. So a powered cooling is not required, but to possibly lower temperatures.

Progress on creating of powerful vertical lasers, for example, Vertical-External Cavity Surface-Emitting Lasers (VECSEL), requires a more powerful cooling. VCSEL arrays require more powerful cooling solutions in terms of cooling capacity.

Thermoelectric coolers as solid-stage heat pumps give a unique reliability at several hundred thousand hours of continuous operation. It is more than 20-25 years of operation without maintenance, replacement, which is important for telecommunication systems.

RMT has specially developed and produce series of miniature powerful TECs optimal for cooling of VCSEL.

Most suitable TECs VCSEL are in general thermoelectric cooler series МС and MD.

For ultra-miniature VCSEL design RMT recommends TEC Series 1MD04, 1MD03 and 1MD02. The smallest TECs of the series are just a little more than a square millimeter footprint. That allows the TECs use for cooled VCSELs in small packages such as TO-37, TO39 and very miniature types like TO46, TO56 and some others.

For high-power lasers or high-power VECSEL type, the matrixes of VCSEL lasers there are larger packages - TO8, TO66.

In addition, RMT offers the sub-assembly solutions – thermoelectric coolers mounted on standard TO-style headers.

All the products are manufactured in whole conformity with the standard of reliability Telcordia GR468 Core. The modules of RMT are fully compliant with RoHS и REACH requirements.

To select suitable solution and the optimal TEC for an application, the Online TEC Assistance is available at RMT’s website. For detailed modeling and calculations the company RMT provides our customers by free software TECCad or iTECPad.

And contact RMT for advice and assistance.