Injection-Locked Coherent Reception Through an Externally Modulated Laser

A lean coherent receiver based on an externally modulated laser is presented. Reception is conducted in virtue of the optical detection capability of a monolithically integrated high-bandwidth electroabsorption modulator and its distributed feedback laser section that serves as a local oscillator. The in-line configuration of the receiver with its partial feed-through of the incident data signal to the local oscillator is further exploited for the purpose of optical injection locking. A locking range of 200 MHz is obtained at an input power level of –27.8 dBm. The proposed low-complexity receiver is being evaluated in an optical access scenario through the use of a commercial off-the-shelf externally modulated laser device rated for 10G applications. Coherent reception of 1 Gb/s on–off keyed data through exclusive use of analog signal processing at the receiver is demonstrated at low bit error ratios of 10−10 and is further shown to be compatible with a loss budget of 40.1 dB at the hard-decision forward error correction threshold. Higher data rates of up to 6.6 Gb/s at a loss budget of 31 dB are facilitated through broadband orthogonal frequency-division multiplexing, for which wavelength locking obviates optical frequency offset correction between the local oscillator and the incident data signal.