Improvements in index alignment method for laser-fiber array packaging

Abstract

An "index alignment" method, based on the registration of fiducial marks, was previously developed for passive alignment of a laser array to a corresponding fiber array. This method has recently been improved and used to fabricate laserfiber array transmitter modules for single-mode operation at 1300 nm.An improved computer-controlled alignment-stage system with machine-vision features has been installed in order to render the alignment procedure faster, more precise, and more reliable; this system was particularly effective in quick achievement of the difficult but necessary angular alignment of the components. Special "self-registration" component-fabrication techniques were also developed to avoid mask-registration errors associated with the fabrication of the laser chip and the fiber carrier. Measures were also taken to improve the accuracy of alignment of the etch mask to the silicon crystallographic axes during fiber-carrier fabrication, and to improve the etch-stop indication process.Test results showed that for single-mode operation at 1300 nm, coupling efficiencies greater than 8% could be achieved, approaching the 9% coupling efficiency observed with active alignment. Tests of a completed module at 1 Gb/s showed values of RIN low enough to permit operation at distances of about 1 km.

Hybrid integration technologies for optical micro-systems

“…Particularly alignment process would be extremely complicated and costly. The passive alignment, which eliminates complicated optical axis precise alignment, can solve this problem [1,2]. Three types of passive alignment technique have already * eiji@su.rcast.u-tokyo.ac.jp been developed: mechanical contact alignment, visual alignment using alignment marks, and solder bump self alignment.…”

Heterogeneous integration towards an ultra-compact and thin optical displacement microsensor

“…The passive alignment technique, which eliminates complicated precise optical axis alignment and removes the need for closed-loop optimization, can solve this problem. Three types of passive alignment techniques have already been developed: mechanical contact alignment [10], visual index alignment using alignment marks [11][12][13], and solder bump self-alignment [14]. We adopted index alignment using alignment marks.…”

Vacuum, confinement, and QCD strings in the vacuum correlator method

“…Accurate assembly of these devices is very important in order to decrease the optical coupling loss on the optical module. The passive alignment method [1][2][3][4] is preferable to the active alignment method in terms of mass production and cost reduction.…”

“…In order to realize efficient optical coupling, three-dimensional alignments are needed. If the vertical position of the waveguide (center of the transmission mode profile) coincides with the active layer of the laser diode automatically, the alignment of the channel waveguide device becomes two dimensional on the Si submount and we can adopt a passive alignment method [1][2][3][4] of using an image processing technique as a horizontal positioning method.…”