Gain control for arbitrary triggering of short pulse lasers

Patent metadata

Field	Value
Publication number	US-9570877-B1
Application number	US-201514986163-A
Country	US
Kind code	B1
Filing date	Dec 31, 2015
Priority date	Dec 31, 2015
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A device may include a transient optical amplifier having stored energy associated with a lower boundary and an upper boundary of a dynamic equilibrium, and a target level defining stored energy for amplifying a high energy input pulse to a higher energy output pulse. The device may include a pump to increase the amplifier's stored energy, and a source to pass low energy control pulses or the high energy input pulse to the amplifier. The device may include a controller configured to maintain the amplifier's stored energy in the dynamic equilibrium by requesting low energy control pulses for the amplifier at a high repetition frequency. The controller may wait to receive a trigger. Based on receiving the trigger, the device may stop passing low energy control pulses to the amplifier, and may pass the high energy input pulse to the amplifier when the amplifier's stored energy reaches the target level.

First claim

What is claimed is:

1. A method, comprising:
continuously pumping a transient optical amplifier thereby increasing the amplifier's stored energy, the amplifier's stored energy associated with three increasing energy levels:
a lower boundary of a dynamic equilibrium;
an upper boundary of the dynamic equilibrium; and
a target level defining stored energy for amplifying a high energy input pulse to a higher energy output pulse;

maintaining the amplifier's stored energy in the dynamic equilibrium by passing low energy control pulses from a source to the amplifier at a high repetition frequency; and
based on receiving a trigger:
stopping passing low energy control pulses to the amplifier,
waiting for the pumping to increase the amplifier's stored energy to the target level,
passing the high energy input pulse to the amplifier,
amplifying the high energy input pulse to a higher energy output pulse thereby decreasing the amplifier's stored energy to a depleted level, below the target level, and
outputting the higher energy output pulse.

2. The method of claim 1 , wherein the source comprises a short pulse laser source having a pulse repetition frequency greater than 5 megahertz (MHz); and a pulse picker, optically connected to the short pulse laser source, to control emission and energy of laser pulses from the short pulse laser source.

3. The method of claim 2 , where controlling the emission and energy of the laser pulses comprises:
passing, partially passing or blocking, by the pulse picker, laser pulses from the short pulse laser source.

4. The method of claim 2 , where stopping passing the low energy control pulses comprises:
blocking, by the pulse picker, laser pulses from the short pulse laser source.

5. The method of claim 2 , where at least one of the short pulse laser source or the pulse picker provide sub-microsecond response time.

6. The method of claim 1 , where the low energy control pulses, the high energy input pulse, and the higher energy output pulse have pulse widths less than one microsecond.

7. The method of claim 1 , where the depleted level is lower than the lower boundary of the dynamic equilibrium.

8. The method of claim 1 , where a center energy level of the dynamic equilibrium is closer to a center energy level of the target level and the depleted level than to the target level or to the depleted level.

9. The method of claim 1 , where a time delay between receiving the trigger and outputting the higher energy output pulse is between approximately 5 nanoseconds and approximately 100 nanoseconds.

10. A device, comprising:
a transient optical amplifier having stored energy associated with three increasing energy levels:
a lower boundary of a dynamic equilibrium;
an upper boundary of the dynamic equilibrium; and
a target level defining stored energy for amplifying a high energy input pulse to a higher energy output pulse;

a pump to increase the amplifier's stored energy;
a source to pass low energy control pulses or the high energy input pulse to the amplifier; and
a controller configured to:
maintain the amplifier's stored energy in the dynamic equilibrium by requesting the source pass low energy control pulses to the amplifier at a high repetition frequency;
wait to receive a trigger; and
based on receiving the trigger:
stop passing low energy control pulses to the amplifier, and
request the source pass the high energy input pulse to the amplifier when the amplifier's stored energy reaches the target level.

11. The device of claim 10 , where the source comprises a laser diode.

12. The device of claim 11 , where the controller, when stopping passing the low energy control pulses, is configured to:
control the laser diode to prevent emission of pulses by the laser diode.

13. The device of claim 10 , where the source comprises a continuous wave laser providing the low energy control pulses as a continuous wave low average power control beam and a second laser providing the high energy input pulse.

14. The device of claim 10 , where the amplifier's stored energy is depleted to a depleted level by amplification of the high energy input pulse; and
where the high repetition frequency is greater than a repetition frequency that would maintain the amplifier's stored energy in equilibrium between the target level and the depleted level without the low energy control pulses.

15. The device of claim 14 , wherein a difference between the upper boundary and the lower boundary is less than or equal to 60 percent of a difference between the target level and the depleted level.

16. The device of claim 14 , wherein a difference between the upper boundary and the lower boundary is less than or equal to 20 percent of a difference between the target level and the depleted level.

17. The device of claim 16 , further comprising outputting the higher energy output pulse; and
where decreasing the difference between the upper boundary and the lower boundary decreases at least one of:
a timing jitter between a time of outputting the higher energy output pulse and a time of receiving the trigger, or
an energy jitter between a desired energy level and an energy level of the higher energy output pulse.

18. The device of claim 10 , where the amplifier comprises at least one of:
one or more single pass amplifiers,
one or more multi-pass amplifiers, or
a combination of one or more single pass amplifiers and one or more multi-pass amplifiers.

19. The device of claim 10 , where the controller is to:
determine that the trigger indicates to provide a series of pulses in a burst; and
request, when the amplifier's stored energy reaches the target level, the high energy input pulse as the series of pulses in a burst.

20. The device of claim 10 , further comprising an output control, after the amplifier, to pass, block, or reduce energy levels of amplified low energy control pulses and higher energy output pulses before output.

21. The device of claim 20 , where the controller is configured to request the output control to block pulses when the controller is requesting low energy pulses from the source.

22. The device of claim 20 , where the output control comprises a pulse picker or a pulse-on-demand.

23. The device of claim 10 , further comprising a nonlinear wavelength converter after the amplifier.

24. The device of claim 10 , where the device receives multiple triggers and outputs multiple higher energy output pulses corresponding to the multiple triggers; and
where a timing jitter and an energy jitter of the multiple higher energy output pulses corresponding to the multiple triggers are less than approximately 1 microsecond and 5%, respectively.

25. A short pulse laser gain regulation method comprising:
pumping, by a laser system, a transient optical amplifier of the laser system, thereby increasing the amplifier's stored energy;
waiting, by the laser system, to receive a trigger;
while the amplifier's stored energy is below a holding energy level, preventing, by the laser system, emission of laser pulses from a pulse source of the laser system into the amplifier;
when the amplifier's stored energy reaches the holding energy level and the trigger has not been received, emitting, by the laser system, low energy control pulses from the pulse source into the amplifier, each low energy pulse decreasing some of the amplifier's stored energy, counteracting the pumping, t

Assignees

• Lumentum Operations Llc

Inventors

• Ammann Hubert
• Benetti Marco

Classifications

• H01S3/0941 Primary

  of a laser diode · CPC title

• H01S3/0085

  Modulating the output, i.e. the laser beam is modulated outside the laser cavity · CPC title

• H01S3/1003

  tunable optical elements, e.g. acousto-optic filters, tunable gratings · CPC title

• H01S3/1001

  by controlling the optical pumping · CPC title

• H01S3/10046

  Pulse repetition rate control (H01S3/11 takes precedence) · CPC title