CMOS-compatible vertical-cavity surface-emitting lasers promise high-speed interconnects

CMOS-compatible vertical-cavity surface-emitting lasers promise high-speed interconnects

At the Materials Research Society meeting (Boston, MA), researchers from Lucent Tech nol ogies--Bell Labs (Holmdel, NJ) described fabrication of 850-nm vertical-cavity surface-emitting lasers (VCSELs). The goal, according to researcher Jack Cunningham, is to support optical-interconnect applications, with speeds of 1 Gbit/s needed within a year and 10 Gbit/s by 2001. Lucent has created devices compatible with silicon-based complementary metal-oxide semiconductor (CMOS) manufacturing processes and designed to lase at a very low threshold current--less than 1 mA--with drive voltages of about 3 to 4 V. The flip-chi¥bonded VCSELs are based on an oxidized to¥mirror and oxidized current aperture that allow them to operate as a bottom-emitter for large-scale integration. The design uses intercavity contacts and a nonalloyed buried contact.

The researchers have succeeded in producing resonantly enhanced emission with a record output of 70 µW/sr. More investigation of the oxide mirror is required. Cunningham says that the design of the structure was compromised to enhance flip-chi¥bonding rather than lasing--a compromise that allows large-scale arrays to be built.