Hybrid Q-switch device, lasers using the same, and method of operation

• US 20040190564A1
• Filed: 01/27/2004
• Published: 09/30/2004
• Est. Priority Date: 01/29/2003
• Status: Abandoned Application

• Current Assignee: Lambda Solutions, Inc.
• Original Assignee: Lambda Solutions, Inc.
• Inventors: Zhou, Wang Long
• Application Number:
  US10/766,706
• Publication Number:
  US 20040190564A1
• Time in Patent Office: Days
• US Class Current: 372/10
• CPC Class Codes: H01S 3/113 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/115 using intracavity electro-optic devices
• CPC Class Codes: H01S 3/117 using intracavity acousto-optic devices
• CPC Class Codes: H01S 3/121 using intracavity mechanical devices
• CPC Class Codes: H01S 3/127 Plural Q-switches

Abstract

A hybrid Q-switch device for a laser device having a laser medium being pumped with energy includes a solid-state saturable absorber element for controlling loss modulation of the laser medium; an active Q-switch element having open and closed states for controlling loss modulation of the laser medium and positioned in series with the laser medium and the absorber element; and, a device for adjusting timing of the open and closed states of the active Q-switch element. The combined loss modulation control from active Q-switch and absorber elements enable generation of a short width, high peak power pulse at a lasing wavelength. Particularly, the loss modulation effects of active and passive Q-switch means are timed to minimize cavity loss at which time a high peak power pulse of small pulse width is generated.

Claims

1. A laser device having a laser medium in a resonator cavity comprising:

a) means for pumping energy into said laser medium to increase gain of said laser device;

b) active Q-switch means having open and close states for controlling loss modulation of said resonator cavity; and

,

c) passive Q-switch means for further controlling loss modulation of said resonator cavity, wherein loss modulation control from active and passive Q-switch means enable generation of a short width, high peak power pulse at a lasing wavelength.

2. The laser device as claimed in claim 1, wherein loss modulation effects of active and passive Q-switch means are timed to minimize cavity loss at which time a high peak power pulse is generated.

3. The laser device as claimed in claim 2, capable of generating high peak power pulse having a width ranging between from about 50 ps to 10 ns.

4. The laser device as claimed in claim 2, wherein when said active Q-switch means is in a closed state, said laser medium absorbs energy to a certain gain level.

5. The laser device as claimed in claim 2, wherein said passive Q-switch means saturates at a time after the active Q-switch enters an open state to enable generation of a high peak power pulse of short duration.

6. The laser device as claimed in claim 2, further comprising means for triggering the active Q-switch means to provide an open time window adjusted to avoid occurrence of sub-pulsing.

7. The laser device as claimed in claim 6, wherein said active Q-switch means comprises an acousto-optical (AO) device for controlling loss modulation at a predetermined pulse repetition frequency.

8. The laser device as claimed in claim 6, wherein said active Q-switch means comprises an electro-optical (EO) crystal for controlling loss modulation at a predetermined frequency.

9. The laser device as claimed in claim 2, wherein said active Q-switch means comprises a rotating chopper device having open slits for controlling loss modulation at a predetermined frequency.

10. The laser device as claimed in claim 2, wherein said laser medium is a solid-state laser material comprising one selected from the group comprising:

Nd;

YAG, and Nd;

YVO₄.

11. The laser device as claimed in claim 2, wherein said passive Q-switch means comprises a solid-state saturable absorber.

12. The laser device as claimed in claim 2, wherein said saturable absorber includes Cr⁴⁺:

YAG.

13. The laser device as claimed in claim 11, wherein said solid-state laser material and said solid-state saturable absorber is physically bonded together.

14. The laser device as claimed in claim 10, wherein said solid-state laser material and said solid-state saturable absorber are integrated.

15. The laser device as claimed in claim 14, wherein said integrated solid-state laser material and said solid-state saturable absorber comprise a YAG crystal co-doped with Nd³⁺ and Cr⁴⁺.

16. A hybrid Q-switch for a laser device having a laser medium being pumped with energy comprising:

a solid-state saturable absorber element for controlling loss modulation of said laser device;

an active Q-switch element having open and closed states for controlling loss modulation of said laser device and positioned in series with said laser medium and said absorber element; and

,

means for adjusting timing of said open and closed states of the active Q-switch element, wherein combined loss modulation control from active Q-switch and saturable absorber elements enable generation of a short width, high peak power pulse at a lasing wavelength.

17. The hybrid Q-switch as claimed in claim 16, wherein when said active Q-switch means is in a closed state, said laser medium absorbs energy to a certain gain level.

18. The hybrid Q-switch as claimed in claim 17, wherein said saturable absorber element saturates at a time after the active Q-switch enters an open state to enable generation of a high peak power pulse of short duration.

19. The hybrid Q-switch as claimed in claim 18, wherein an open state of said active Q-switch means is adjusted to avoid occurrence of sub-pulsing.

20. The hybrid Q-switch as claimed in claim 18, wherein said active Q-switch element includes an electro-optical crystal triggered to adjust time of said open and close states.

21. The hybrid Q-switch as claimed in claim 18, wherein said active Q-switch element includes an acousto-optical crystal triggered to adjust said open and close states and thereby control optical gain of said laser medium.

22. The hybrid Q-switch as claimed in claim 18, wherein said active Q-switch element includes a rotating chopper device having one or more slits each of predetermined width for adjusting time of said open and close states.

23. The hybrid Q-switch as claimed in claim 22, wherein a diameter of the chopper is less than about 12.0 cm in diameter.

24. The hybrid Q-switch as claimed in claim 22, wherein a width of each opening slit is larger than a diameter of a laser beam emitted by said laser device.

25. The hybrid Q-switch as claimed in claim 22, further including two overlapped identical choppers each having slits, said choppers having their slits crossover so that a final opening width is changeable by adjusting a degree of mutual crossover.

26. A method of operating a laser device having a laser medium comprising the steps of:

a) pumping the laser medium to increase gain of said laser device;

b) controlling loss modulation of a resonator cavity of said device by active Q-switch means;

c) controlling loss modulation of a resonator cavity by passive Q-switch means,

wherein loss modulation control from active and passive Q-switch means enable generation of a short width, high peak power pulse at a lasing wavelength.

27. The method as claimed in claim 26, further including the step of timing loss modulation effects of active and passive Q-switch means to minimize cavity loss.

28. The method as claimed in claim 26, wherein said controlling loss modulation step b) includes:

closing said active Q-switch means for a time sufficient for said laser medium to absorb energy to a certain gain level.

29. The method as claimed in claim 26, wherein said absorber element saturates at a time after the active Q-switch enters an open state to enable generation of a high peak power pulse of short duration.

30. The method as claimed in claim 26, further comprising the step of:

triggering the active Q-switch means to provide an open time window adjusted to avoid occurrence of sub-pulsing.