DIGITAL LASER PULSE SHAPING MODULE AND SYSTEM

• US 20090323741A1
• Filed: 06/29/2009
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Deladurantaye, Pascal, Duchesne, François, Taillon, Yves, Parent, André, Mimeault, Yvan, Jacob, Michel
• Granted Patent: US 8,073,027 B2
• Time in Patent Office: Days
• US Class Current: 372/25
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/32 Material from living organisms, e.g. skins
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/382 by boring
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: G06F 1/0321 Waveform generators, i.e. devices for generating periodical functions of time, e.g. direct digital synthesizers G06F1/0314, G06F1/035 take precedence
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 5/06216 Pulse modulation or generation
• CPC Class Codes: H01S 5/146 using a fiber as external cavity

Abstract

A digital pulse shaping module for controlling a pulsed laser oscillator according to a digital input waveform is provided. The pulse shaping module includes a clock generator generating a plurality of phase-related clock signals and a shape generator which outputs a digital shape signal corresponding to the digital input waveform in Double Data Rate in response to the clock signals. A DAC converts the digital shape into an analog shape signal. The analog shape signal may be used to control the current source of a laser seed source or modulators in the laser oscillator shaping a seed light signal. Optionally, the pulse shaping module may also output a gate control signal having a predetermined timing relationship with respect to the digital shape signal.

Claims

1. A digital pulse shaping module for controlling a pulsed laser oscillator according to a digital input waveform, comprising:

a clock generator generating a plurality of phase-related clock signals at a same clock frequency;

a shape generator outputting a digital shape signal corresponding to said digital input waveform, said shape generator operating in Double Data Rate in response to said clock signals; and

a Digital-to-Analog Converter, hereinafter DAC, receiving the digital shape signal and converting the same into an analog shape signal.

2. The digital pulse shaping module according to claim 1, wherein the plurality of phase-related clock signals comprises a Clock_0 signal and a Clock_180 lagging half a period behind said Clock_0 signal.

3. The digital pulse shaping module according to claim 2, wherein the shape generator comprises a shape sub-module comprising:

parallely operating first and a second shape state machines respectively clocked by the Clock_0 and Clock_180 signals and each outputting a corresponding output shape; and

a shape DDR switch alternatingly outputting the output shape from said first and second shape state machines as said digital shape signal.

4. The digital pulse shaping module according to claim 3, further comprising a shape memory buffer storing a plurality of predetermined waveforms, each shape state machine comprising selecting means for selecting any one of said predetermined waveforms as the digital input waveform.

5. The digital pulse shaping module according to claim 4, wherein the shape memory buffer comprises a pulse shape data buffer for storing pulse shape and a pulse duration data buffer for storing pulse duration data.

6. The digital pulse shaping module according to claim 4, wherein each of said shape state machines comprises shape switching means for dynamically switching the corresponding output shape between two of said predetermined waveforms.

7. The digital pulse shaping module according to claim 4, wherein each of said shape state machines has a shape mode wherein the output shape corresponds to a selected one of said predetermined waveforms, and a QCW mode where the output shape is a quasi-continuous wave shape.

8. The digital pulse shaping module according to claim 7, wherein each of said shape state machine outputs said quasi-continuous wave shape by default.

9. The digital pulse shaping module according to claim 2, wherein the plurality of phase-related clock signals further comprises a Clock_90 signal and a Clock_270 signal respectively lagging a quarter of a period and three-quarters of a period behind said Clock_0 signal.

10. The digital pulse shaping module according to claim 9, wherein the shape generator further comprises a clock DDR switch providing a DAC clock signal to the DAC, said clock DDR switch being clocked by the Clock_90 and Clock_270 signals.

11. The digital pulse shaping module according to claim 1, further comprising a frequency synthesizer generating a high frequency clock control signal inputted to said DAC.

12. The pulse shaping platform according to claim 1, further comprising a shape buffer driver receiving the analog shape signal and generating a control shape signal adapted for controlling said pulse laser oscillator.

13. The digital pulse shaping module according to claim 1, further comprising QCW means for outputting a quasi-continuous wave as said digital shape signal.

14. The digital pulse shaping signal according to claim 13, wherein the QCW means comprise a frequency measurement module for measuring the frequency of an external QCW trigger signal, said frequency measurement module outputting a QCW output flag dependent on said frequency.

15. The digital pulse shaping module according to claim 2, wherein the shape generator further comprises a gate sub-module generating a gate signal having a predetermined timing relationship with respect to the digital shape signal.

16. The digital pulse shaping module according to claim 15, wherein the gate sub-module comprises:

parallely operating first and a second gate state machines respectively clocked by the Clock_0 and Clock_180 signals and each outputting a corresponding gate output;

first and second variable delay line respectively associated with the first and second gate state machines and imposing a delay on the corresponding gate output, thereby generating a delayed gate output; and

a gate DDR switch alternatingly outputting the delayed gate output from said first and second gate state machines as said gate signal.

17. The digital pulse shaping module according to claim 15, further comprising a gate buffer driver receiving the analog gate signal and generating a control gate signal.

18. The digital pulse shaping module according to claim 2, wherein the shape generator further comprises a synchronization sub-module generating a trigger synchronization signal having a predetermined timing relationship with respect to a light pulse emitted by said laser oscillator responsive to an external trigger signal.

19. The digital pulse shaping module according to claim 18, wherein the synchronization sub-module comprises:

parallely operating first and a second synchronization state machines respectively clocked by the Clock_0 and Clock_180 signals and each outputting a corresponding synchronization output responsive to said external trigger signal;

first and second synchronization variable delay lines respectively associated with the first and second synchronization state machines and imposing a delay on the corresponding synchronization output, thereby generating a delayed synchronization output; and

a synchronization DDR switch alternatingly outputting the delayed synchronization output from said first and second synchronization state machines as said trigger synchronization signal.

20. The digital pulse shaping module according to claim 18, wherein the delay imposed by each synchronization delay line is user-defined.

21. The digital pulse shaping module according to claim 1, further comprising a microcontroller.

22. The digital pulse shaping module according to claim 1, further comprising a high speed digital logic circuit, the microcontroller, clock generator and shape generator being embedded thereon.

23. The digital pulse shaping module according to claim 22, wherein the high speed digital logic circuit is a FPGA or an ASIC.

24. The digital pulse shaping module according to claim 1, in combination with a connector interface interfacing communication between said digital pulse shaping module and user equipment.

25. The combination of claim 23, wherein the connector interface provides an external trigger signal to the digital pulse shaping module in response to a trigger command from the user equipment.

26. The combination of claim 25, wherein the connector interface outputs a trigger synchronization signal having a predetermined timing relationship with respect to a light pulse emitted by said laser oscillator responsive to said external trigger signal.

27. The combination of claim 24, wherein the connector interface provides a shape switching signal to the digital pulse shaping module in response to a shape selection command from the user equipment.

28. A pulse laser system for generating laser pulses, said pulsed laser system comprising:

a digital pulse shaping module comprising;

a clock generator generating a plurality of phase-related clock signals at a same clock frequency;

a shape generator outputting a digital shape signal corresponding to said digital input waveform, said shape generator operating in Double Data Rate in response to said clock signals;

a Digital-to-Analog Converter, hereinafter DAC, receiving the digital shape signal and converting the same into an analog shape signal; and

a shape buffer driver receiving the analog shape signal and generating a control shape signal; and

a laser oscillator receiving said control shape signal and generating said laser pulses in accordance therewith.

29. The pulsed laser system according to claim 28, wherein the laser oscillator comprises a pulsed seed light source generating said light pulses, the pulsed seed light source having a current source controlled by said control shape signal.

30. The pulsed laser system according to claim 28, wherein the digital pulse shaping module further comprises:

a gate sub-module generating a gate signal having a predetermined timing relationship with respect to the digital shape signal; and

a gate buffer driver receiving the analog gate signal and generating a control gate signal.

31. The pulsed laser system according to claim 30, wherein the laser oscillator comprises:

a seed source generating a continuous light beam; and

first and second modulators disposed in a path of said continuous light beam and modulating the same to provide said laser pulses, the first modulator and second modulators being respectively controlled by the control shape signal and the control gate signal.

32. The pulsed laser system according to claim 31, wherein the laser oscillator further comprises a first gain medium disposed between the first and second modulators.

33. The pulsed laser system according to claim 32, wherein the laser oscillator further comprises a second gain medium disposed downstream the second modulator.

34. The pulsed laser system according to claim 30, wherein the laser oscillator comprises:

a pulsed seed light source generating said light pulses, the pulsed seed light source having a current source controlled by said control shape signal; and

a modulator disposed downstream the pulsed seed laser source, the modulator being controlled by the control gate signal.

35. The pulsed laser system according to claim 28, wherein the laser oscillator comprises:

a pulsed seed light source generating a light signal of sub-pulses;

a first modulator disposed downstream the pulsed seed laser source and modulating the light signal to form said laser pulses, each laser pulse comprising a train of said sub-pulses, the modulator being controlled by the control shape signal.

36. The pulsed laser system according to claim 35, further comprising a sampling assembly providing a trigger signal synchronized with said sub-pulses to the digital pulse shaping module, the sampling assembly comprising:

an optical coupling device coupling a fraction of the light signal generated by the pulsed seed light source;

a detector for detecting said fraction of the light signal and outputting a corresponding detected signal; and

a trigger generator receiving said detected signal and generating therefrom the trigger signal synchronized with said sub-pulses.

37. The pulsed laser system according to claim 35, wherein the pulsed seed light source is a mode-locked laser.

38. The pulsed laser system according to claim 35, wherein:

the digital pulse shaping module further comprises a gate sub-module generating a gate signal having a predetermined timing relationship with respect to the digital shape signal, and a gate buffer driver receiving the analog gate signal and generating a control gate signal; and

the laser oscillator further comprises a second modulator disposed downstream the first modulator, the second modulator being controlled by the control gate signal.

39. The pulsed laser system according to claim 38, wherein the laser oscillator further comprises a first gain medium disposed between the first and second modulators.

40. The pulsed laser system according to claim 39, wherein the laser oscillator further comprises a second gain medium disposed downstream the second modulator.