Patent ID: 8855484

Claim:
A method for controlling optical power and extinction ratio over an entire temperature range, the method being applicable to a fiber-optic transceiver, wherein the fiber-optic transceiver is connected to an electronic device, is configured for generating or receiving a laser beam under control of the electronic device, and comprises a transmitter optical subassembly (TOSA), a laser driver, a controller IC, and a thermal sensor, the TOSA being provided therein with a laser diode but does not requiring require a monitoring photodiode, the laser driver being configured for driving the laser diode under control of the controller IC so as for the laser diode to generate a laser beam to be transmitted outward through an optical fiber, and the thermal sensor being configured for sensing a temperature of the laser diode, the method comprising the steps, performed by the controller IC, of: receiving a relationship between an optical power P(t) and an on-current I(t) of the laser diode over an entire temperature range, receiving operation parameters including bias currents I 0 (t) and modulation currents I 1 (t) of the laser diode in the entire temperature range, and writing the relationship and the operation parameters into a memory of the controller IC; wherein the relationship is obtained through substituting manufacturer-provided characteristic data concerning threshold currents I th (t) and corresponding slope efficiencies SE(t) at a plurality of specific temperatures, of the fiber-optic transceiver or of the laser diode into a first equation and a second equation, respectively, as follows: I th ( t )= I 0 + K 1 *exp( t/t 1 ) the first equation: SE ( t )= S 0 − K s *exp( t/t s ), the second equation: to determine characteristic constants in the first and second equations by an approximation method and then determine the relationship according to threshold currents I th (t) and corresponding slope efficiencies SE(t) in the entire temperature range obtained from the first and second equations, respectively; wherein the characteristic constants in the first and second equations are I 0 , K 1 , t 1 , S 0 , K s , and t s ; and wherein the operation parameters are obtained, through manually adjusting a bias current I 0 (t n ) and a modulation current I 1 (t n ) of the laser diode at a normal temperature t n so as for the laser diode to generate expected optical powers P 0 (t n ) and P 1 (t n ) at the normal temperature t n , according to a third equation, as follows: P ( t )=( I ( t )− I th ( t ))* SE ( t ), the third equation: and obtaining a current temperature t i of the laser diode through the thermal sensor, and controlling the laser driver according to the relationship, the operation parameters and the current temperature t i , so that the laser driver drives the laser diode to generate a laser beam having an expected optical power and an expected extinction ratio.