10-Gb/s 1.59- $\mu \text{m}$ DFB-LD Transmission Over 20 km SMF With No Compensation

We present a 10-Gb/s 1.59- $\mu \text{m}$ directly modulated laser (DML) capable of a 20-km transmission in a standard single-mode fiber without the use of any other compensation techniques. For the fabricated distributed feedback laser diode chips, the static, dynamic, and transmission properties were tested. During these tests, it appears that the signal quality was improved after a certain transmission distance. To examine the change in signal shape during the transmission, a time-resolved back-to-back signal was measured and its transmission properties simulated. The simulated results of a time-resolved signal show good agreement with those obtained from a transmission test. As a result, it was confirmed that a 10-Gb/s DML signal (with an extinction ratio of 4 to 5 dB) can be transmitted at up to 20 km with a power penalty of less than 1 dB.