We demonstrate a laser-based micro-bonding method for Vertical Cavity Surface Emitting Lasers (VCSELs) that enables
practically sufficient joint strength, while securing the output power before bonding. VCSELs have great potential for
optical interconnects because of their low threshold current and high-speed modulation capability. As for packaging of
VCSELs, flip-chip bonding (FCB), among others, has been investigated because it facilitates the coupling of laser
emission into fibers and waveguides. Conventional schemes for FCB, however, entail thermo-compressing stages and
therefore the thermal and mechanical stresses involved are prone to cause defects in the lasing media, leading to quality
defects. To overcome this problem, we have come up with a modified FCB method that can reduce such stress by
employing laser irradiation to efficiently heat joints minimizing heat-affected regions. A micro-bonding system used in
the experiments has an infrared fiber laser for heating, a diffractive beam splitter for parallel processing, a mounting head,
and a slider for precise alignment and translation. VCSEL pads are kept in contact with counter pads on a substrate with
AuSn solder placed between them. The split and focused beams by the element are guided to strike the joining points
through the substrate, heating and melting the solder to attain a tight joint.
We present a grating array illuminator that serves at two different wavelengths. The grating was designed by simulated annealing method and drawn in photoresist by direct laser lithography that we have developed on optical disk mastering technology. Upon grating reconstruction with two chosen wavelengths, 1064 and 532 nm, from Nd:YAG lasers, two arrays of 9 split beams with the same pitch were reconstructed. The illuminator performance was found rather sensitive to profile errors, which was supported by computer analysis.