Passive alignment and soldering technique for optical components

Abstract

The passive-alignment-packaging technique presented in this work provides a method for mounting tolerance-insensitive optical components e.g. non-linear crystals by means of mechanical stops. The requested tolerances for the angle deviation are ±100 µrad and for the position tolerance ±100 µm. Only the angle tolerances were investigated, because they are more critical. The measurements were carried out with an autocollimator. Fused silica components were used for test series. A solder investigation was carried out. Different types of solder were tested. Due to good solderability on air and low induced stress in optical components, Sn based solders were indicated as the most suitable solders. In addition several concepts of reflow soldering configuration were realized. In the first iteration a system with only the alignment of the yaw angle was implemented. The deviation for all materials after the thermal and mechanical cycling was within the tolerances. The solderability of BBO and LBO crystals was investigated and concepts for mounting were developed

Comparison of monochromatic and broadband monitoring of optical interference filters

“…In consequence mirror mounts have been developed with only screw and solder joints and no organic subcomponents. 9,10 The soldering technique was inherited from the development of soldered diode bars and soldered laser crystals. The optics' mechanical interface to the laser baseplate is given by a submount made of metal, typically aluminum.…”

“…A solderable organic free package has also been developed for Faraday isolators, Pockels cells and nonlinear crystals. 10 Because those are transmitting optics their alignment stability is less critical compared to mirrors except for nonlinear crystals whose conversion efficiency depends on the angle and the temperature. BBO Pockels cells and TGG Faraday isolators are depicted in Figure 12.…”

Optical path difference evaluation of laser-soldered optical components

“…Localized heating also enables a sequential build-up of systems as thermal dealignment during assembly is avoided. Contact-free heating could be provided by Joule heating using integrated resistive layers as demonstrated by the Pick&Align soldering technique [15]. Laser irradiation is a very versatile tool to reflow localized solder volumes as shown by the TRIMO approach for surface-mounted optics [16], by thin film laser soldering processes [17], and by Solderjet Bumping [18].…”

Solderjet bumping technique used to manufacture a compact and robust green solid-state laser

“…Laser-based soldering processes are especially well suited for the joining of optical components made of fragile and brittle materials such as glasses, ceramics and optical crystals, due to a localized and minimized input of thermal energy. Different techniques of heating solder alloys by laser irradiation are proposed using either thin film solder layers [3], Pick&Align resistance soldering technique [4] and [5] or the jetting of laser-molten solder droplets [6]. This so called Solderjet Bumping is a technique adapted from flip chip processing of semiconductor devices also allowing for the flux-free and contact-free processing of optical components and 3D-packaging.…”