Laser pulse synthesis system
View Patent ↗A laser pulse synthesis system is provided. A further aspect of the present system uses a phase-only modulator to measure ultrashort laser pulses. An additional aspect achieves interferences between split subpulses even though the subpulses have different frequencies. Yet another aspect of a laser system employs multi-comb phase shaping of a laser pulse. In another aspect, a laser system includes pulse characterization and arbitrary or variable waveform generation through spectral phase comb shaping.
1. A method of using a laser system, the method comprising:
(a) emitting at least one laser pulse;
(b) shaping the pulse with a phase-only modulator;
(c) separating the pulse into at least two replica subpulses by using a phase in the modulator that interacts with at least two frequency subsets of the pulse, each subset representing a pulse;
(d) measuring a characteristic induced by at least one of the subpulses after step (c);
(e) supplying a linear pulse function to only some pixels of the modulator for at least one of the subpulses; and
(f) supplying a different phase function to other of the pixels of the modulator for at least another of the subpulses, simultaneously with step (e).
2. The method of claim 1 , wherein the shaper is a two-dimensional phase mask which supplies the different functions to a single pulse.
3. The method of claim 1 , wherein the measured characteristic is a duration of the pulse.
4. The method of claim 1 , wherein the measured characteristic is autocorrelation.
5. The method of claim 1 , wherein the measured characteristic is cross-correlation.
6. The method of claim 1 , wherein the modulator is a programmable spatial light modulator, and the subpulses are temporally separated.
7. A method of using a laser system comprising:
(a) separating a laser pulse into at least two subpulses in time but not in space;
(b) independently shaping each of the subpulses using different chirp functions in a piecewise manner, performing the shaping of the subpulses with a phase-only modulator;
(c) supplying a first shaping function to some pixels of the modulator for the one of the subpulses; and
(d) supplying a second and different shaping function to some pixels of the modulator for at least a second of the subpulses.
8. The method of claim 7 , further comprising shaping the pulse with a phase-only modulator.
9. The method of claim 7 , further comprising shaping the pulse with a phase- and polarization-only modulator.
10. The method of claim 7 , further comprising using software instructions to automatically vary a pulse shaper to shape the subpulses.
11. The method of claim 7 , further comprising generating and characterizing optical pulse trains where a spectral phase of every laser pulse in the train is independently controlled.
12. The method of claim 7 , further comprising using the laser pulse for machining a workpiece.
13. The method of claim 7 , further comprising using the laser pulse for biomedical imaging.
14. A method of using a laser system comprising:
(a) separating a laser pulse into at least two subpulses in time but not in space;
(b) independently shaping each of the subpulses using different chirp functions in a piecewise manner; and
(c) characterizing the laser pulse in which the phase of an input pulse to an amplifier is shaped to enable measuring of the output pulse using a spectrometer located substantially at a target, and without requiring mechanical movement of any optics during operation.
15. The method of claim 14 , further comprising performing the shaping of the subpulses with a phase-only modulator, supplying a first shaping function to some pixels of the modulator for the one of the subpulses, and supplying a second and different shaping function to some pixels of the modulator for at least a second of the subpulses.
16. A method of using a laser system, the method comprising:
(a) generating and characterizing optical pulse trains where a spectral phase of every laser pulse in the train is independently controlled;
(b) splitting a laser spectrum into at least two groups of frequencies distributed over an entire spectrum bandwidth;
(c) adjusting the two groups of frequencies such that a desired amplitude and bandwidth for each subpulse is achieved;
(d) imposing the desired phase mask on each of the subsets of frequencies; and
(e) creating a piecewise phase function across the original spectrum to generate a desired pulse sequence.
17. The method of claim 16 , further comprising using a frequency comb to generate the multi-pulse train.
18. The method of claim 16 , further comprising obtaining frequency resolved autocorrelation of the pulse at the focus by creating at least two pseudoreplicas and recording a second harmonic generation spectrum as a function of their relative time delay.
19. The method of claim 16 , further comprising shaping the subpulses with a phase-only modulator, supplying a first shaping function to some pixels of the modulator for the one of the subpulses, and supplying a second and different shaping function to some pixels of the modulator for at least a second of the subpulses.
20. The method of claim 16 , further comprising using software instructions to automatically vary a pulse shaper to shape the subpulses.
21. The method of claim 16 , further comprising using the laser pulse for machining a workpiece.
22. The method of claim 16 , further comprising using the laser pulse for biomedical imaging.
23. The method of claim 16 , further comprising detecting nonlinear optical excitation in the laser pulse.
24. A method of using a laser system, the method comprising:
(a) emitting a laser pulse;
(b) shaping the pulse;
(c) splitting the pulse into subpulses being of identical duration to the original pulse except having different frequencies;
(d) causing nonlinear optical interference between the subpulses, and changing the interference with a pulse shaper and without mechanical component movement; and
(e) measuring interferometric correlation between the subpulses.
25. The method of claim 24 , wherein the interference is constructive.
26. The method of claim 24 , wherein the interference is destructive.
27. The method of claim 24 , further comprising temporally delaying one interfering subpulse from another.
28. The method of claim 24 , further comprising measuring a carrier frequency of at least one of the subpulses.
29. The method of claim 24 , further comprising changing a carrier frequency of at least one of the subpulses.
30. The method of claim 24 , further comprising encoding communications information into the subpulses with a pulse shaper.
31. The method of claim 24 , further comprising using the subpulses for optical imaging.
32. The method of claim 24 , further comprising using the subpulses to micromachine a workpiece.
33. The method of claim 24 , further comprising double passing the pulse through the pulse shaper to reduce space-time coupling.
34. The method of claim 24 , wherein the correlation is autocorrelation.
35. The method of claim 24 , wherein the correlation is cross-correlation.
36. A method of using a laser system, the method comprising:
(a) emitting at least one original laser pulse, each having a duration of less than 1 picosecond;
(b) shaping the original laser pulse with at least two distinct phase functions;
(c) using each phase function to sample available spectral bandwidth of the original pulse;
(d) creating pulse replicas, each having the same pulse duration as the original pulse;
(e) controlling the replica pulses by distributing each of the phase functions across the spectrum of the associated pulse;
(f) creating an additional reference pulse with a pulse shaper and software instructions; and
(g) causing the reference pulse to scan across a pulse sequence to provide a cross-correlation of the sequence.
37. The method of claim 36 , further comprising controlling relative amplitude between the replica pulses.
38. The method of claim 36 , further comprising controlling relative bandwidth between the replica pulses.
39. The method of claim 36 , further comprising controlling relative duration between the replica pulses.
40. The method of claim 36 , further comprising controlling relative inter-replica time delay between the replica pulses.
41. The method of claim 36 , further comprising controlling absolute phase between the replica pulses.
42. The method of claim 36 , further comprising using the laser pulse for machining a workpiece.
43. The method of claim 36 , further comprising using the laser pulse for biomedical imaging.
44. The method of claim 36 , further comprising detecting nonlinear optical excitation in the laser pulse.
45. The method of claim 36 , further comprising characterizing the laser pulse in which the phase of an input pulse to an amplifier is shaped to enable measuring of the output pulse using a spectrometer located substantially at a target, and without requiring mechanical movement of any optics during operation.
46. A method of using a laser system, the method comprising:
(a) emitting at least one original laser pulse, each having a duration of less than 1 picosecond;
(b) introducing at least two distinct phase functions by pulse shaping;
(c) creating pulse replicas, each having the same pulse duration as the original pulse;
(d) distributing each phase function across the spectrum of the associated pulse;
(e) encoding pulse sequences with information;
(f) detecting the pulse sequences based on a nonlinear optical process;
(g) creating an additional reference pulse; and
(h) causing the reference pulse to scan across a pulse sequence to provide a cross-correlation of the sequence.
47. The method of claim 46 , further comprising introducing π phase shifts in contiguous pixels of a pulse shaper, where the total number of zero and π pixels is equal, if a given replica pulse needs to be cancelled.
48. The method of claim 46 , further comprising introducing π phase shifts in alternate phase locations, where the total number of zero and π pixels is equal, if a given replica pulse needs to be cancelled.
49. The method of claim 46 , further comprising a pulse shaper and software instructions creating the additional reference pulse.
50. The method of claim 14 , further comprising using a spectrometer to send a signal to a controller containing software that automatically controls and varies a pulse shaper.
51. The method of claim 50 , wherein the controller includes the software which causes the pulse shaper to introduce π phase shifts in contiguous pixels of the shaper, where the total number of zero and π pixels is equal, if a given replica pulse needs to be cancelled.
52. The method of claim 50 , wherein the controller includes the software which causes the pulse shaper to introduce π phase shifts in alternate phase locations, where the total number of zero and π pixels is equal, if a given replica pulse needs to be cancelled.
53. The method of claim 14 , wherein a duration of the laser pulse is less than 1 picosecond.
54. The method of claim 1 , further comprising:
using CW diode lasers to generate the at least one laser pulse with a duration less than 10 fs; and
generating an optical frequency comb with at least one nonlinear fiber.
55. The method of claim 1 , further comprising:
using the at least one laser pulse for microscopy; and
performing the separating and measuring steps with programmed software instructions in a computer.
56. The method of claim 7 , further comprising:
using CW diode lasers to generate multiples of the laser pulse, at least some of which having a duration less than 10 fs; and
generating an optical frequency comb with at least one fiber.