Uncooled Fabry-Perot lasers for QPSK transmission

Abstract
We investigate the use of uncooled lasers in an optical fiber transmission system employing quadrature-phase-shift keyed (QPSK) signals on subcarriers. The BER of a 2 Mb/s QPSK channel is measured in a system containing 60 subcarriers. Error-free performance (BER <10/sup -9/) is achieved over a wide range of modulation depths. This demonstrates that these inexpensive lasers can be used in multi-channel digital systems.