Optical Hybrids

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Optical Hybrids
WBS 1.1.1.4

• K.K. Gan
• The Ohio State University

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Outline
l Introduction l Opto-package prototypes l
Opto-hybrid board design l Cost and schedule
summary l Conclusions
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ATLAS Pixel Opto-link
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Opto-package
l 2 fibres VCSEL PIN l coupled VCSEL power
gt 300 mW _at_ 10 mA l VCSEL tolerance l 50
mm in z (along fibre) l 25 mm in r
(transverse to fibre)
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Opto-package Designs
l Marconi P 8 silicon/alumina pieces P
use silicon mirror for 450 light reflection
P high cost l Taiwan P 3 G-10 pieces
P cleave fibre at 450 P fibers permanently
attached need voliton connector P low
cost l OSU P 2 pieces P cap with
fibers can be attached to package at end of
module assembly P low cost
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OSU Design
l connector concept design P use precisely
fabricated cap and base for alignment P
simple two-piece design for mass production and
cost reduction l cap P 2 holes for
fibers l base P deposit gold traces for wire
bonding, VCSEL and PIN placements
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Base and Cap
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Cap and Base Prototypes
l produced caps and bases (rounded corners)
using machinable ceramic P material tested
aluminum silicate and macor P difficult to
obtain consistent precision _
redesign base with square corners for ease of
fabrication by Hybrid-Tek P alumina
sheet ground to proper thickness and cut into
strips P have produced bases with
precision within specification P 3D
traces have good connectivity _ fabricate
cap with Ultem (polyetherimide) for radiation
tolerance (10 Grad) P use manual micro
mold injection to save development time
P can fabricate several quality caps per hour
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Prototype Result
l produced 10 packages l VCSELs have fast
rise and fall time lt 1 ns l PINs have good
responsitivity 0.5 A/W l coupled power gt 300
mW in both VCSELs simultaneously for 8
packages with different combinations of bases and
caps _ demonstrated feasibility of
fabricating high precision caps and bases l no
cross-talk between VCSEL and PIN above 20 mA
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Cap with Precisely Fabricated Cavity
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Base with PIN and VCSELs
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Completed Opto-package
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no cross talk above 20 mA
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Summary on Opto-package
l principle of two-piece connector concept
demonstrated P precision bases with 3D
traces of good connectivity fabricated P
precision caps fabricated _ packages
produce optical power above specification
_ negligible cross-talk between VCSEL and PIN l
ability to produce precise die placement jig is a
concern P required six trials (one week)
for current jig
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Opto-hybrid Board
l convert optical signal into electrical signal
and vice verse l contains 6 sets of opto-pack,
VDC, and DORIC l electrical signal to/from
module channel through 60-pin connector l
layout to serve 7 modules is ready P will
convert to serve 6 modules P first
submission will use FR-4 for cost saving P
2nd and 3rd prototypes will use BeO l board is
compatible with Taiwan opto-pack
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Opto-hybrid
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Conclusions
l principle of fabrication of opto-pack
demonstrated l no major technical challenge in
opto-hybrid board fabrication P compatible
with Taiwan opto-pack P experience in
opto-pack prototyping is very useful
for mounting opto-packs on opto-hybrid board