Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S5/00—Semiconductor lasers
  • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
  • H01S5/042—Electrical excitation ; Circuits therefor
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S5/00—Semiconductor lasers
  • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
  • H01S5/042—Electrical excitation ; Circuits therefor
  • H01S5/0428—Electrical excitation ; Circuits therefor for applying pulses to the laser

Definitions

• the present invention relates to activating a laser diode by applying a high current during a transient rise time for the laser, and a lower voltage during operation of the laser.
• a common electrical circuit to start a laser diode is shown in Figure 1.
• a prior art electrical circuit design for a laser diode includes a voltage source 12, which is applied to start laser diode 10 as well as to supply the power required for conducting continuous operation of the laser diode.
• a computer 18 initiates transmission of digital data to be imaged using laser diode 10.
• the data is supplied in synchronization with voltage source 12 through a digital control unit 15, typically a field programmable gate array (FPGA).
• the current supplied to the laser diode 10 is controlled by current control unit 17.
• an apparatus for driving a laser diode includes a first voltage source for powering the laser diode during a transient period of operation of the laser diode.
• a second voltage source having a lower voltage than the first voltage source, powers the laser diode during continuous operation of the laser diode.
• the present invention describes an apparatus and method for invoking a laser diode having a short rise/fall time while maintaining high system power efficiency.
• the invention utilizes two different power voltage sources and one current drive module in conjunction with the laser diodes.
• a higher power voltage source is used during the transient rise time, and thus, for a short period.
• the lower power voltage source is used for continuous laser diode operation.
• the higher power supply source level will be used to drive the current during the transient time of the laser diode operation, at the stage of starting the laser diode, and not during normal continuous laser diode operation.
• a lower power supply source will be used.
• Figure 1 is a prior art schematic illustrating a laser diode voltage driver control
• Figure 2 is a schematic illustrating a laser diode dual voltage driver control each using a dedicated power supply external power supply;
• Figure 3 is a schematic illustrating a laser diode dual voltage driver control using a single external power supply for both voltage drivers
• Figure 4 is a schematic illustrating laboratory results for laser driver power supply simulation.
• the invention discloses methods and apparatus for a laser diode driver.
• a laser driver according to the present invention, has the following advantages: a) The laser driver has a short rise time, typically less than 250 nanoseconds, using a high power voltage source. b) The life expectancy of the laser diode power voltage source is extended by using a lower power voltage source than the one applied for starting the laser diode, during the continuous operation of the laser diode. c) A smooth transient of current through the diode prevents high temperature from developing in the diode. Referring to Figure 3, computer 18 sends data via the expose bus to be imaged by laser diode 10. Laser diode 10 is started by the transient voltage source 13.
• the level of the transient voltage 13 is controlled by the digital control unit 15, which applies the required voltage level (usually between -3v to -5v) through the voltage boost control line 14 activating voltage boost circuit 19, synchronized with the data received from computer 18.
• digital control unit 15 controls the digital to analog converter 16, to apply the required voltage level for starting laser diode 10. After laser diode 10 is started, digital control unit 15 opens switch 11 to connect external voltage source 12 to supply the voltage laser diode 10 for continuous diode operation, typically in voltage levels of -2.5 v.
• Figure 4 shows voltage and current curves at the boost circuit 19, shown in Figure 3, during operation of the voltage for laser diode 10.
• the current overshoot profile 33 A is essentially characterized by two factors: the current slew rate (measured by current value divided by the rise time value 31) and the switching point to the voltage source 12, used during continuous operation of laser diode 10.
• the boost circuit is already at the state of maximum duty cycle value, according to the setting received from digital control unit 15.
• high voltage values are applied to laser diode 10, enabling the smooth transient current 33 to reach to maximum values in a very short rise time 31.
• Figure 4 shows a measured rise time 36 for a current increase from OA to 15A to be achieved in 250 nanoseconds.
• the continuous voltage source 12 takes control.
• Figure 4 shows the smooth transition between the two voltage sources as it is indicated in the charts showing smooth transient current 33 and smooth transient voltage 34.
• the current command 35 is off, the current in the diode falls as well, fall time 32 is measured at approximately 250 nanoseconds.
• FIG. 1 shows transient voltage source 13 generated by the same external power supply, amplified by a voltage boost circuit 19.
• Figure 2 depicts use of two distinct power supplies, external voltage source 12 for supplying continuous voltage lower than the voltage generated by power supply 23 for transient voltage purpose. The switching between the two power supplies is performed by opening switch 11 and closing switch 24 for transient voltage selection. The activation of voltage source 12 is done by closing switch 11 and opening switch 24.

Landscapes

• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Optics & Photonics (AREA)
• Semiconductor Lasers (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (4)

Families Citing this family (11)

Citations (10)

Family Cites Families (3)

• 2008
  • 2008-03-03 US US12/040,943 patent/US20090219964A1/en not_active Abandoned
• 2009
  • 2009-02-27 JP JP2010549637A patent/JP2011513988A/ja not_active Withdrawn
  • 2009-02-27 EP EP09719215A patent/EP2250715A1/en not_active Withdrawn
  • 2009-02-27 WO PCT/US2009/001250 patent/WO2009114074A1/en not_active Ceased

Patent Citations (10)

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