Opto Packages

We plan to use VCSELs and epitaxial Si PIN diodes for the on-detector opto-electronics. This requires special packages to be non-magnetic, low mass and radiation hard. We are investigating four routes:

MITEL VCSELs in the GEC package. The idea is to use a Si package similar to that used for the GEC LED/PIN devices. First tests have shown that we can get 500 microW of optical power into a 50 micron core fibre. AC tests ave been performed by GEC. Good results were obtained with BER tests at 100 MHz. The devices could be operated up to 1 GHz.No micro lenses were required and the alignment was purely pasive using the v-groove. The concept for the new package is based on a silicon baseplate on a ceramic tile. The PIN diode is mounted on the ceramic tile. The VCSELs are mounted on separate ceramic tiles which then sit on the silicon baseplate. An aluminised silicon mirror is used to turn the light from the vertical to horizontal direction. The fibres are placed in v-grooves in a separate silicon lid which fits onto the silicon base. 5 VCSEL only package have been produced by GEC and tested by us. The results of these tests are available here.

Marconi test results

Results from the Marconi measurements of these packages are available here.

The drawings for the final ATLAS style 2 VCSEL+PIN diode package are available here (pdf file).
Dimensioned drawing of the completed package (pdf file).

Photos of the piece parts are available here

A preliminary estimate of the radiation length of the package is available here.

A report on the tests of the first of the phase 2 VCSEL/PIN packages is available here.

Honeywell discussed using their VCSELs to produce a low mass package with 2 VCSELs and one PIN diode on a ceramic package.We have tested a 12 way VCSEL array package (Ecstatic) which worked well and gave good results for radiation tests. However it seems unlikely that Honeywell will be able to produce ATLAS style packages in time.

Ohio State University are prdoucing a ceramic package (base) to hold the VCSELs and the PINs. They would produce a separate package (cap) which would contain holes for mounting the fibres. The cap would mount accuately onto the base, ensuring the alignment of the fibres with the PINs and the VCSELs. They will produce a first prototype of a VCSEL only package, using MITEL VCSELs. The drawings for these prototypes are available here. A short report on the results of the first measurements is available here. OSU have now produced better packages. Results of BER tests of the first OSU package are available here. The OSU group have developed their own BER tester. Thei first results are available here (pdf file with BER plot). An improved package with a good ground plane has been made and this eliminated the cross talk problem. The test results are available (pdf file).

Taiwan are working on a low mass ATLAS style 2 VCSEL + 1 PIN diode package. They have produced 20 prototype packages with Truelight VCSELs and Centronic epitaxial Si PIN diodes. More details of their design are available here The first tests of integration of this package into the ATLAS links system was very successful and a short report is available (pdf file). Even better results were obtaimed with improved PIN bias decoupling. The results are available here.