Laser system and laser light generation method

• US 9,184,555 B2
• Filed: 06/06/2014
• Issued: 11/10/2015
• Est. Priority Date: 03/28/2011
• Status: Active Grant

• Current Assignee: Gigaphoton, Inc. (Komatsu Ltd.)
• Original Assignee: Gigaphoton, Inc. (Komatsu Ltd.)
• Inventors: Yoshino, Masaya, Onose, Takashi, Wakabayashi, Osamu
• Primary Examiner(s): Rodriguez, Armando
• Application Number:
  US14/298,563
• Publication Number:
  US 20140341239A1
• Time in Patent Office: 522 Days
• US Class Current: 1/1
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/10023 by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/134 in gas lasers
• CPC Class Codes: H01S 3/1636 Al2O3 (Sapphire)
• CPC Class Codes: H01S 3/2251 ArF, i.e. argon fluoride is comprised for lasing around 193 nm
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2325 Multi-pass amplifiers, e.g. regenerative amplifiers
• CPC Class Codes: H01S 3/2333 Double-pass amplifiers
• CPC Class Codes: H01S 3/2366 comprising a gas as the active medium H01S3/10092, H01S3/2383 take precedence

Abstract

A laser system may include: a master oscillator configured to output pulsed laser light; an amplification device for amplifying the pulsed laser light from the master oscillator; a first timing detector configured to detect a first timing at which the master oscillator outputs the pulsed laser light; a second timing detector configured to detect a second timing at which the amplification device discharges; and a controller configured to, based on results of detection by the first timing detector and the second timing detector, control at least one of the first timing and the second timing so that the amplification device discharges when the pulsed laser light passes through a discharge space of the amplification device.

Claims

1. A laser system comprising:

a master oscillator including a seed laser and an amplifier and configured to generate pulsed laser light;

an amplification device configured to amplify the pulsed laser light from the master oscillator;

a first timing detector configured to detect a first timing at which the pulsed laser light passes through a predetermined position;

a second timing detector configured to detect a second timing at which the amplification device discharges; and

a controller configured to, based on results of detection by the first timing detector and the second timing detector, control at least one of the first timing and the second timing so that the amplification device discharges when the pulsed laser light passes through a discharge space of the amplification device,

wherein the master oscillator further includes at least one optical shutter disposed in an optical path between the seed laser and the amplification device,

wherein the predetermined position is a position where the pulsed laser light passes through after the optical shutter, and

wherein the controller is configured to control at least one of a timing at which the optical shutter is put into an open state and a timing at which the amplification device discharges based on the results of detection by the first timing detector and the second timing detector.

2. The laser system according to claim 1, wherein

the controller is configured to calculate a difference between the first timing and the second timing, and control at least one of a timing at which the master oscillator outputs pulsed laser light and a timing at which the amplification device discharges based on the calculated difference.

3. The laser system according to claim 1, wherein the master oscillator further includes a pumping laser configured to output pumping light to the seed laser;

wherein the controller is configured to control at least one of a timing at which the pumping laser oscillates and a timing at which the amplification device discharges based on the results of detection by the first timing detector and the second timing detector.

4. The laser system according to claim 1, wherein the second timing detector is configured to detect discharge light resulting from a discharge occurring in the discharge space of the amplification device as the second timing.

5. The laser system according to claim 1, wherein

the amplification device includes a circuit having a magnetic switch for causing a discharge in the discharge space, and

the second timing detector is configured to detect turning on and off of the magnetic switch as the second timing.

6. The laser system according to claim 1, wherein the second timing detector includes a current sensor and is configured to detect a timing at which a current caused by discharge produced at the discharge space of the amplification device flows as the second timing.

7. The laser system according to claim 1, wherein the seed laser is configured to output the pulsed laser light having a pulse duration that is longer than a period for which the controller puts the optical shutter in the open state.

8. The laser system according to claim 1, wherein the optical shutter includes:

an electro-optical element;

a first optical filter disposed on an optical input end side of the electro-optical element;

a second optical filter disposed on an optical output end side of the electro-optical element; and

a power source connected to the electro-optical element, the power source being configured to apply a voltage to the electro-optical element.

9. The laser system according to claim 8, wherein the electro-optical element is a Pockels cell.

10. The laser system according to claim 8, wherein each of the first and second optical filters includes at least one polarizer.

16. The laser system according to claim 1, wherein the amplifier is a multipass amplification-type amplifier.

17. The laser system according to claim 1, wherein the amplifier is a Fabry Perot-type amplifier.

18. The laser system according to claim 1, wherein the master oscillator further includes an Nd:

YAG laser.

19. The laser system according to claim 1, wherein the seed laser is a solid-state laser device.

11. A laser system comprising:

a master oscillator configured to generate pulsed laser light;

an amplification device configured to input the pulsed laser light outputted from the master oscillator and amplify the pulsed laser light;

at least one optical shutter disposed in an optical path of the pulsed laser light to be inputted into the amplification device;

a first timing detector located on a position below the optical shutter in the optical path and configured to detect a first timing at which the pulsed laser light passes therethrough;

a second timing detector configured to detect a second timing at which the amplification device discharges; and

a controller configured to, based on results of detection by the first timing detector and the second timing detector, control at least one of a first timing at which the master oscillator outputs pulsed laser light, a timing at which the optical shutter is put into an open state and a timing at which the amplification device discharges.

12. The laser system according to claim 11, wherein the optical shutter includes:

a Pockels cell;

a polarizer;

a power source connected to the Pockels cell and configured to apply a voltage to the Pockels cell.

13. The laser system according to claim 11, wherein the second timing detector is configured to detect discharge light resulting from a discharge occurring in a discharge space of the amplification device as the second timing.

14. The laser system according to claim 11, wherein

the amplification device includes a circuit having a magnetic switch for causing a discharge in a discharge space, and

the second timing detector is configured to detect turning on and off the magnetic switch as the second timing.

15. The laser system according to claim 11, wherein the second timing detector includes a current sensor and is configured to detect a timing at which a current caused by discharge produced at a discharge space of the amplification device flows as the second timing.

20. A laser system comprising:

a master oscillator including a seed laser and an amplifier and configured to generate pulsed laser light;

an amplification device configured to amplify the pulsed laser light from the master oscillator;

a first timing detector configured to detect a first timing at which the pulsed laser light passes through a predetermined position;

a second timing detector configured to detect a second timing at which the amplification device discharges; and

a controller configured to, based on results of detection by the first timing detector and the second timing detector, control at least one of the first timing and the second timing so that the amplification device discharges when the pulsed laser light passes through a discharge space of the amplification device,

wherein the second timing detector includes a current sensor and is configured to detect a timing at which a current caused by discharge produced at the discharge space of the amplification device flows as the second timing.