Method and system for a pulsed laser source emitting shaped optical waveforms

• US 7,742,511 B2
• Filed: 09/12/2008
• Issued: 06/22/2010
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: 6091571 Canada, Inc. (MKS Instruments Incorporated)
• Inventors: Murison, Richard, Reid, Benoit, Boula-Picard, Reynald, Panarello, Tullio
• Primary Examiner(s): Nguyen; Dung T
• Application Number:
  US12/210,028
• Publication Number:
  US 20090067455A1
• Time in Patent Office: 648 Days
• Field of Search: 372/26, 372/6, 372/50.11
• US Class Current: 372/26
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• CPC Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/0912 Electronics or drivers for the pump source, i.e. details of drivers or circuitry specific for laser pumping laser diode drivers H01S5/042
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/1001 by controlling the optical pumping
• CPC Class Codes: H01S 3/10015 by monitoring or controlling, e.g. attenuating, the input signal
• CPC Class Codes: H01S 3/1003 tunable optical elements, e.g. acousto-optic filters, tunable gratings
• CPC Class Codes: H01S 3/10069 Memorized or pre-programmed characteristics, e.g. look-up table [LUT]
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2333 Double-pass amplifiers

Abstract

A laser system for processing a workpiece includes a tunable pulsed laser source having an output comprising a set of optical pulses. The tunable pulsed laser source includes a seed source, an optical circulator having a first port coupled to the seed source, a second port, and a third port, a modulator driver, and an amplitude modulator coupled to the modulator driver. The tunable pulsed laser source also includes a first optical amplifier characterized by an input end and a reflective end and a second optical amplifier coupled to the third port of the optical circulator. The laser system also includes a controller configured to adjust laser parameters of the tunable pulsed laser source, a supporting member configured to support the workpiece, and an optical system configured to adjust laser beams from the tunable pulsed laser source and direct them towards the workpiece.

Claims

1. A laser system for processing a workpiece, the laser system comprising:

a tunable pulsed laser source having an output comprising a set of optical pulses, wherein the tunable pulsed laser source comprises;

a seed source adapted to generate a seed signal;

an optical circulator having a first port coupled to the seed source, a second port, and a third port;

a modulator driver adapted to produce an electrical waveform;

an amplitude modulator coupled to the modulator driver and adapted to receive the electrical waveform, wherein the amplitude modulator is characterized by a first side coupled to the second port of the optical circulator and a second side;

a first optical amplifier characterized by an input end and a reflective end, wherein the input end is coupled to the second side of the amplitude modulator; and

a second optical amplifier coupled to the third port of the optical circulator;

a controller configured to adjust laser parameters of the tunable pulsed laser source;

a supporting member configured to support the workpiece; and

an optical system configured to adjust laser beams from the tunable pulsed laser source and direct them towards the workpiece.

2. The laser system of claim 1 further comprising a wavelength converter.

3. The laser system of claim 2 wherein the wavelength converter comprises a harmonic generator configured to generate harmonic wavelengths from a fundamental wavelength.

4. The laser system of claim 3 wherein the wavelength converter further comprises a plurality of mirrors configured for a laser beam from the tunable pulsed laser source to bypass the wavelength converter.

5. The laser system of claim 3 wherein the harmonic generator comprises at least one non-linear crystal.

6. The laser system of claim 1 further comprising a Digital-to-Analog Converter (DAC) configured to provide electrical waveforms.

7. The laser system of claim 1 wherein the workpiece comprises at least a first layer and a second layer, the first layer and the second layer comprising different materials.

8. The laser system of claim 7 wherein the set of optical pulses comprises:

a first set of pulses characterized by a first set of shapes, a first set of durations and a first set of intensities; and

a second set of pulses characterized by a second set of shapes, a second set of durations, and a second set of intensities, wherein the first set of pulses is different from the second set of pulses.

9. The laser system of claim 8 wherein the first set of pulses is used in processing the first layer and the second set of pulses is used in processing the second layer.

10. The laser system of claim 1 further comprising a sensor coupled to the controller and configured to detect a phase of laser processing.

11. The laser system of claim 10 wherein the phase of laser processing comprises an end of laser processing.

12. The laser system of claim 1 further comprising a digital-to-analog converter configured to generate the electrical waveform, the digital-to-analog converter being characterized by a sampling rate of 500 megasamples/second or faster and an analog electrical bandwidth larger than 100 MHz.

13. A method of laser processing, the method comprising:

outputting a first set of optical pulses from a tunable pulsed laser source toward a workpiece, wherein the workpiece comprises at least a first layer of a first material and a second layer of a second material, the first material being different from the second material, wherein the tunable pulsed laser source comprises;

a seed source adapted to generate a seed signal;

an optical circulator having a first port coupled to the seed source, a second port, and a third port;

a modulator driver adapted to produce an electrical waveform;

an amplitude modulator coupled to the modulator driver and adapted to receive the electrical waveform, wherein the amplitude modulator is characterized by a first side coupled to the second port of the optical circulator and a second side;

a first optical amplifier characterized by an input end and a reflective end, wherein the input end is coupled to the second side of the amplitude modulator; and

a second optical amplifier coupled to the third port of the optical circulator;

processing the first layer using the first set of optical pulses;

outputting a second set of optical pulses from the tunable pulsed laser source toward the workpiece, wherein the second set of optical pulses is different from the first set of optical pulses; and

processing the second layer using the second set of optical pulses.

14. The method of claim 13 wherein at least one of the first set of optical pulses or the second set of optical pulse are characterized by a fundamental wavelength, the method further comprising converting the fundamental wavelength to a harmonic wavelength.

15. The method of claim 13 further comprising:

detecting a signal associated with a termination of processing of the first layer; and

receiving the detected signal at a controller coupled to the tunable pulsed laser source.

16. The method of claim 13 wherein:

the first set of optical pulses comprises a first set of pulses characterized by a first set of shapes, a first set of durations, and a first set of intensities; and

the second set of optical pulses comprises a second set of pulses characterized by a second set of shapes, a second set of durations, and a second set of intensities.

17. The method of claim 13 wherein a duration for switching from the first set of optical pulses to the second set of optical pulses is shorter than a duration between any two consecutive optical pulses.

18. The method of claim 13 wherein laser processing comprises at least one of drilling, cutting, or cleaning.