Method of controlling a diode device for use in optical storage systems

Abstract

A system and method is provided which compensates for the effects of relaxation oscillations and turn-on delays of diode laser devices. In particular, there is provided a method and system for tuning the shape of the power profile of an output optical signal and its position with respect to a channel bit clock of an optical recording system.

1 . A method of controlling a diode laser device having a lazing threshold value, the method comprising the acts of:
 supplying a control signal to the diode laser device wherein at a predetermined turn-on time, the control signal comprises a bias signal having a value which exceeds the threshold value, and at a predefined time before the predetermined turn-on time, the control signal comprises a pre-bias signal having a magnitude which is less than the threshold value and which extends for a time period, and wherein, the predefined time, magnitude, and time period of the pre-bias signal is selected to provide a predetermined output, power profile of the output optical signal,   outputting from the diode laser device an. optical signal when the control signal exceeds the threshold.   
     
     
         2 . The method of  claim 1 , wherein the pre-bias signal comprises a series of pre-bias pulses, having respective predefined times, magnitudes and- extents, wherein the combination of the plurality of pre-bias pulses is selected to cause the output optical signal to have a predetermined power profile. 
     
     
         3 . The method of  claim 1 , wherein the pre-bias signal is a stepped value. 
     
     
         4 . The method of  claim 1 , wherein the predetermined- turn-on time is determined by a clock signal. 
     
     
         5 . The method of  claim 1 , wherein the predetermined turn-on time is selected to provide a predetermined output power profile of the output optical signal. 
     
     
         6 . The method of  claim 1 , wherein the value of the pre-bias signal is selected to provide a predetermined output power profile of the output optical signal. 
     
     
         7 . A method of controlling a diode laser device having a lazing threshold value the method, comprising the acts of:
 supplying a control signal from a controller to the diode laser device wherein at a predetermined turn-on time, the control signal comprises a bias signal having a. value which exceeds the threshold value, and at a predefined time before the predetermined turn-on time, the control signal comprises a pre-bias signal, having a magnitude which is less than the threshold, value and which extends for a time period, and -wherein the predefined time, magnitude, and time period of the pre-bias signal are selected to provide a predetermined output power profile of the output optical signal, and wherein the threshold value is a predetermined constant,   outputting from the diode laser device an optical signal when the control signal exceeds the threshold.   
     
     
         8 . The method of  claim 7 , wherein the pre-bias signal comprises a series of pre-bias pulses, having respective predefined times, magnitudes and extents, wherein the combination of the plurality of pre-bias pulses are selected to cause the output optical signal to have a predetermined power profile. 
     
     
         9 . The method of  claim 7 , wherein the pre-bias signal is a stepped value. 
     
     
         10 . The method of  claim 7 , wherein the predetermined- turn-on time is determined by a clock signal. 
     
     
         11 . The method of  claim 7 , wherein the predetermined turn-on time is determined by a required selected to provide a predetermined output power profile of the output optical signal. 
     
     
         12 . The method of  claim 7 , wherein the value of the pre-bias signal is selected to cause a predetermined output power profile of the output optical signal. 
     
     
         13 . An optical system comprising,
 a controller operable to output a control signal; and   a laser diode device operable to receive a control signal from the controller, and to output an optical signal when the control signal exceeds a threshold, value for lazing of the laser diode, wherein at a predetermined turn-on time, the control signal comprises a bias signal having a value which exceeds the threshold value and at predefined time before the predetermined turn-on time, the control signal comprises a pre-bias signal having a magnitude which is less than the threshold value and which extends for a time period, and wherein the predefined time, magnitude, and time period- of the pre-bias signal are selected for providing a predetermined output power profile of the output optical signal.   
     
     
         14 . The optical system of  claim 13 , wherein the controller is operable to supply a pre-bias signal comprising a series of pre-bias pulses, having respective predefined times, magnitudes and extents, wherein the combination of the plurality of pre-bias pulses for causing the output optical signal to have the predetermined power profile. 
     
     
         15 . The optical system of  claim 13 , wherein the controller is operable to supply a pre-bias signal to the laser diode device that varies with time to provide multiple different magnitudes at different times. 
     
     
         16 . The optical system of  claim 13 , wherein the controller is operable to output to the laser diode device as the control signal and before the predetermined turn-on time, a pre-bias signal, which has a value less than the threshold value, and is determined by a clock signal of the system. 
     
     
         17 . The optical system of  claim 13 , wherein the controller is operable to output to the laser diode device as the control signal and before the predetermined, turn-on time, a pre-bias signal which has a value less than the threshold value, wherein the controller is operable to determine the predetermined turn-on time for providing a predetermined output power profile of the output optical signal. 
     
     
         18 . The optical system of  claim 13 , wherein the controller is operable to output to the laser diode device as the control signal and before the predetermined turn-on time, a pre-bias signal which has a value less than the threshold value, wherein the controller is operable to determine the value of the pre-bias signal for providing a predetermined output power profile of the output optical signal. 
     
     
         19 . The method of  claim 1  wherein the time period of the magnitude is less than the predefined, time. 
     
     
         20 . The method of  claim 1  wherein the magnitude of the pre-bias signal varies during the predefined time.