Patent ID: 9089084
Filing Date: 2015-07-21
Classification: H04B,H05K,Y10T

Abstract:
1. A method to form an optical transceiver that installs a semiconductor laser diode (LD), comprising steps of: before the LD is installed in the optical transceiver, measuring an I-L characteristic of the LD, the I-L characteristic relating a current supplied to the LD with optical power output from the LD; installing the LD within the optical transceiver; and determining a modulation current as varying a temperature of the optical transceiver by a feedback loop with an initial condition by referring to a look-up-table (LUT) relating the modulation current (Im) with temperatures (T), the modulation current being supplied to the LD to keep an extinction ratio of light output from the optical transceiver in a preset range as a bias current (Ib) supplied to the LD is automatically determined by an automatic power control (APC) circuit to keep an average of the optical power output from the LD in a preset level, wherein the step of determining the modulation current includes steps of: setting the initial condition in the feedback loop; monitoring the extinction ratio of the light output from the optical transceiver; and modifying the modulation current according to an equation of: where Im(cur) is the modulation current currently supplied to the LD, the Im(tar) is a next modulation current modified from the current modulation current Im(cur), ER(cur) is the extinction ratio currently monitored, and ER(tar) is a target extinction ratio, wherein the LUT is revised by replacing data based on the I-L characteristic of the LD with the modulation current practically determined for the light output from the optical transceiver.