Technical Insight
High temperature 1300nm VCSELs arrive (research review)
Long wavelength VCSELs have yet to provide substantial CW output power above 70C, which limits their commercial use in uncooled packages. This problem is addressed in two papers appearing in Photonics Technology Letters (2000, 12(12), p1595 and p1707). The first paper by V Jayaraman and co-workers ("Gore Photonics") describes 1310 nm VCSELs that provide 0.5 mW CW operation up to the commercially important 85C operating temperature, and continue in CW mode up to 115C. The device combines three epitaxial growth structures and a double wafer bonding diffusion process. The top 850 nm VCSEL is processed with two top contacts and emits downward into the 1310 nm VCSEL through a 1310 nm undoped AlGaAs DBR (see figure). The InP-based 1310 nm active device re-emits back through the 850 nm VCSEL. In the second paper, J Geske from UCSB and co-authors from Gore demonstrate transmission measurements from 1300 nm VCSELs using the structure described above. Error-free operation of 2.5 Gbit/s is achieved for a distance of 50 km. The device operated in CW single transverse mode at 1332 nm and featured a side mode suppression ratio of 55 dB. BER measurements showed that the transmission distance was attenuation-limited and that it suffered a 0.1 dB per penalty for reflection feedback of 25 dB at 5 m and 27 dB at 5.5 km.
