Thermally controlled external cavity tuneable laser

摘要

The present invention relates to an external-cavity tuneable laser including a gain medium (2) an a tuneable mirror (8), wherein at least the tuneable mirror is in thermal contact, with a thermally conductive platform (10). The tuneable mirror lays substantially horizontally on the thermally conductive platform significantly thereby improving the thermal contact of the tuneable mirror with the platform. The laser beam from the gain medium is directed onto the tuneable mirror, which is mounted substantially horizontally with respect to the thermally conductive platform, by means of a deflector (6) that deflects the beam or a large part of it towards on of the principal surfaces of the tuneable mirror. The resulting laser cavity is therefore a folded cavity. The thermally conductive platform is preferably thermally coupled to TEC (11) that provides thermal control for the platform. In a preferred embodiment, the deflector is a beam splitter that deflects part of the incoming light and transmits the remaining part. A beam splitter as deflector a more compact laser assembly can be envisaged. According to a preferred embodiment of the invention, the portion of light transmitted through the beam splitter forms the output laser beam. In other words, the external-cavity laser outputs a laser beam on the side of the wavelength selective elements (the tuneable mirror and, if any, the channel grid), i.e., on the side of the front facet of the laser diode. With this laser design, a collimating lens to collimate the output laser beam is not necessary.