Solid-state laser

Abstract

A method for assembling an optically pumped solid-state laser having an extended cavity is disclosed. The method comprises the steps of providing a casing, mounting a TEC and a base plate in the casing, and mounting a plurality of laser components on the base plate using a UV and heat curing adhesive. Once the laser components are correctly positioned and aligned on the base plate, the adhesive is pre-cured using UV radiation. Final curing of the adhesive is obtained by subjecting the entire laser package to an ambient temperature of at least 100° C. The base plate is preferably selected to have a CTE similar to that of the laser components in order to facilitate the high temperature curing. A preferred material for the base plate is AlSiC.

Description

TECHNICAL FIELD [0001]The present invention generally relates to improvements in or relating to optically pumped solid-state lasers. In particular, the present invention relates to improvements in or relating to solid-state lasers having extended cavities and a plurality of laser components and optical surfaces.RELATED ART [0002]U.S. Pat. No. 5,170,409 discloses a resonator assembly suited for a diode pumped solid-state laser. The resonator assembly comprises a transparent support plate, e.g. formed from Pyrex, having a coefficient of thermal expansion significantly lower than common metals. Mirror mounts are bonded to the support plate using a UV curable adhesive. Before curing the adhesive using UV radiation, the position of the parts can be adjusted until proper alignment is achieved. By using a support plate formed from a material with a low coefficient of thermal expansion, the stability of the laser is said to be enhanced.[0003]U.S. Pat. No. 6,178,188 discloses a laser assembl...

AI Technical Summary

Benefits of technology

[0008]The inventive technology disclosed herein aims generally towards improving manufacture, performance and long-term stability of optically pumped solid-state lasers. In particular, the inventive technology aims towards advancing manufacture as well as operational performance and longevity of lasers having an extended cavities, i.e. non-microchip lasers, comprising multiple elements and optical surfaces. An exemplary laser targeted by the inventive improvements disclosed herein may have a cavity length of about 10-30 mm. For such a laser, although comparatively compact, mechanical tolerances for proper operation are very demanding. Typically, components and elements in the laser should meet tolerances of about 0.1 mrad in angle and about 10 μm in translation.

[0013]Using high temperature curing adhesives would greatly improve the robustness and ruggedness of the lasers. However, and as indicated above, the laser must be designed specifically for the purpose of being heated to such high temperatures, or else the laser would typically not be operational following the harsh high temperature treatment.

Problems solved by technology

Unfortunately, thermal cure adhesives may require a long cure time.

This is explained to be a drawback in that special design configurations of optoelectronic component assemblies may obstruct light paths and thus cause poor curing of the adhesive.

Despite the above efforts, there have been issues in the art relating to the manufacture of optically pumped solid-state lasers that limits production, long-term stability and high output powers, particularly for such lasers having an extended cavity with a plurality of laser components and optical surfaces.

For such a laser, although comparatively compact, mechanical tolerances for proper operation are very demanding.

Since operation of the laser causes temperature gradients in the laser, stresses induced by thermal expansion may eventually lead to mechanical fatigue and output power degradation.

Similar stress on the laser can also be caused by thermal shock and mechanical movement during transport.

An identified source of optical surface contamination is out-gassing from adhesives used for securing laser components to the base plate of the laser.

Over time, however, these adhesives may out-gas contaminants that adhere to optical surfaces in the laser.

Such contamination is particularly harmful for sensitive, short-wavelength quasi three-level lasers.

It is indeed a challenge to devise a laser having an extended cavity and multiple laser components and optical surfaces, which can withstand being heated as a package to above 100° C. Even temperatures as high as 150° C. may be required in some instances.

However, and as indicated above, the laser must be designed specifically for the purpose of being heated to such high temperatures, or else the laser would typically not be operational following the harsh high temperature treatment.

Even if the CTE of the base plate and the laser components mounted thereon is matched, there may still be issues relating to temperature gradients within the package unless dimensions of for example the base plate are properly selected.

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