Laser system using ultrashort laser pulses

• US 7,450,618 B2
• Filed: 10/04/2002
• Issued: 11/11/2008
• Est. Priority Date: 01/30/2001
• Status: Expired due to Term

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Dantus, Marcos, Lozovoy, Vadim V.
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): FORDE, DELMA ROSA
• Application Number:
  US10/265,211
• Publication Number:
  US 20030099264A1
• Time in Patent Office: 2,230 Days
• Field of Search: 372/9, 372 25- 27, 372/28, 372/40, 372/22, 250281-288
• US Class Current: 372/25
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61N 5/062 Photodynamic therapy, i.e. excitation of an agent
• CPC Class Codes: G01B 9/02014 by using pulsed light
• CPC Class Codes: G01B 9/02044 Imaging in the frequency domain, e.g. by using a spectrometer
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01N 21/6402 Atomic fluorescence; Laser induced fluorescence
• 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

Abstract

A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and a spectrometer. Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan system and method characterize the spectral phase of femtosecond laser pulses. Fiber optic communication systems, photodynamic therapy and pulse characterization tests use the laser system with additional aspects of the present invention.

Claims

1. A system comprising:

a laser operable to emit a laser beam pulse;

a pulse shaper operable to shape the laser beam pulse with encoded characteristics;

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse;

a fiber optic cable carrying the laser beam pulse from the pulse shaper;

a crystal operable to separate multiple frequencies of the pulse;

a detection device operable to detect the characteristics of the shaped laser beam pulse as separated by the crystal; and

a unit connected to the device operably decoding the characteristics;

wherein the pulse shaper is operably provided with a phase function allowing the shaped pulse to travel through the fiber optic cable without substantially suffering nonlinear distortion.

2. The system of claim 1 wherein the laser beam pulse is encoded with a routing address.

3. The system of claim 2 wherein the laser beam pulse is encoded with multiple routing addresses and a second, subsequent laser beam pulse is emitted from the laser and is also encoded by the pulse shaper with multiple routing addresses.

4. The system of claim 3 wherein each routing address contained in the laser beam pulse is encoded by the pulse shaper and corresponds to separate frequencies after second harmonic generation.

5. The system of claim 2 wherein the laser beam pulse is encoded with communications message data.

8. The system of claim 1 wherein the crystal is a second harmonic generation crystal located in a path between the pulse shaper and the detection device.

9. The system of claim 1 wherein the crystal is a thick crystal.

13. The system of claim 1 wherein the laser is a femtosecond laser operable to emit a single laser beam pulse of less than about 50 femtosecond pulse duration.

14. The system of claim 1 wherein the laser operably transmits a laser beam pulse of less than 11 femtosecond duration.

15. The system of claim 1 wherein the pulse shaper is operable to control amplitude and phase of the laser beam pulse.

16. The system of claim 1 wherein the pulse shaper includes an adjustably deformable mirror.

17. The system of claim 1 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

18. The system of claim 1 wherein the detecting device is a CCD camera.

6. A system comprising:

a laser operable to emit a laser beam pulse;

a pulse shaper operable to shape the laser beam pulse with encoded characteristics;

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse;

a crystal operable to separate multiple frequencies of the pulse;

a detection device operable to detect the characteristics of the shaped laser beam pulse as separated by the crystal; and

a unit connected to the device operably decoding the characteristics;

a main transmitting controller; and

multiple remote initial-transmitting communications sources connected to the transmitting controller;

the main transmitting controller operably causing the pulse shaper to encode multiple successive laser beam pulses differently.

7. The system of claim 6 wherein the main transmitting controller, laser and pulse shaper act as a main communications transmitter to send encoded optical signals to the to a receiver, including the crystal and detection device, in order to decode the characteristic in an asynchronous manner without autocorrelation and without interferometry.

55. The system of claim 6 wherein the laser beam pulse is encoded with communications message data.

56. The system of claim 6 wherein the laser is a femtosecond laser operable to emit a laser beam pulse of less than about 50 femtosecond duration.

57. The system of claim 6 wherein the laser operably transmits a laser beam pulse of less than 11 femtosecond duration.

58. The system of claim 6 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse;

and

wherein the main transmitting controller, laser and pulse shaper act as a main communications transmitter to send encoded optical signals to the to a receiver, including the crystal and detection device, in order to decode the characteristic in an asynchronous manner without autocorrelation and without interferometry.

10. A system comprising:

a laser operable to emit a laser beam pulse;

a pulse shaper operable to shape the laser beam pulse with encoded characteristics;

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse;

a crystal operable to separate multiple frequencies of the pulse;

a detection device operable to detect the characteristics of the shaped laser beam pulse as separated by the crystal; and

a unit connected to the device operably decoding the characteristics;

wherein the unit operably determines phase distortions in the pulse.

59. The system of claim 10 wherein the laser beam pulse is encoded with communications message data.

60. The system of claim 10 wherein the laser is a femtosecond laser operable to emit a laser beam pulse of less than about 50 femtosecond duration.

61. The system of claim 10 wherein the laser operably transmits a laser beam pulse of less than 11 femtosecond duration.

62. The system of claim 10 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse;

and

wherein the main transmitting controller, laser and pulse shaper act as a main communications transmitter to send encoded optical signals to the to a receiver, including the crystal and detection device, in order to decode the characteristic in an asynchronous manner without autocorrelation and without interferometry.

11. A system comprising:

a laser operable to emit a laser beam pulse;

a pulse shaper operable to shape the laser beam pulse with characteristics;

an optic component operable to separate multiple frequencies of the pulse;

a detection device operable to detect the characteristics of the shaped laser beam pulse as separated by the component;

a unit connected to the device operably sensing the characteristics;

wherein the pulse shaper has a fixed wave form on a substrate;

and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

12. The system of claim 11 further comprising a fiber optic cable carrying the laser beam pulse from the pulse shaper.

63. The system of claim 12 wherein the laser beam pulse is encoded with communications message data as the characteristic, and the unit decodes the data.

64. The system of claim 12 wherein the laser is a femtosecond laser operable to emit a laser beam pulse of less than about 50 femtosecond duration, and the optic component is a crystal.

65. The system of claim 12 wherein the laser operably transmits a laser beam pulse of less than 11 femtosecond duration.

66. The system of claim 12 further comprising a lens located between the pulse shaper and the optic component, the lens causing the spectrum of the pulse to converge upon the optic component in a phase matching angle manner for subsequent dispersion and separation by the optic component across substantially the entire spectrum of the pulse;

and

wherein the main transmitting controller, laser and pulse shaper act as a main communications transmitter to send encoded optical signals to the to a receiver, including the optic component and detection device, in order to decode the characteristic in an asynchronous manner without autocorrelation and without interferometry.

118. The system of claim 12 wherein the fixed wave form is permanently molded on the substrate which is polymeric.

19. A system comprising:

a laser operable to emit a laser beam pulse;

a pulse shaper operable to shape the laser beam pulse with encoded characteristics;

multiple frequencies of the pulse being separated;

a detection device operable to detect the characteristics of the shaped laser beam pulse as separated;

a unit connected to the device operably decoding the characteristics;

wherein the detecting device includes an array of optical fibers with multiples of the unit being connected downstream of the corresponding fibers; and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

67. The system of claim 19 wherein the laser beam pulse is encoded with communications message data.

68. The system of claim 19 wherein the laser is a femtosecond laser operable to emit a laser beam pulse of less than about 50 femtosecond duration.

69. The system of claim 19 wherein the laser operably transmits a laser beam pulse of less than 11 femtosecond duration.

70. The system of claim 19 further comprising:

a crystal separating the pulse; and

a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse;

wherein the main transmitting controller, laser and pulse shaper act as a main communications transmitter to send encoded optical signals to the to a receiver, including the crystal and detection device, in order to decode the characteristic in an asynchronous manner without autocorrelation and without interferometry.

20. A system comprising:

sequential laser beam pulses;

a pulse shaper operably varying pulse characteristics from one of the sequential pulses to another;

a component operably receiving the pulses as shaped by the pulse shaper in a converging phase matching angle manner and then causing each of the pulses to diverge into separate color frequencies; and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

21. The system of claim 20 further comprising a single detection device operable to simultaneously detect characteristics for a plurality of the frequencies of each of the shaped laser beam pulses as separated by the component which is an optic component, and the detection device subsequently sending a separate output signal corresponding to each separate frequency detected.

22. The system of claim 20 wherein at least one of the laser beam pulses is encoded with multiple communications routing addresses.

23. The system of claim 22 wherein each routing address contained in the laser beam pulse is encoded by the pulse shaper in a separate frequency region.

24. The system of claim 20 wherein at least one of the laser beam pulses is encoded by the pulse shaper with communications message data.

26. The system of claim 20 wherein the component is a crystal.

27. The system of claim 26 wherein the crystal is a second harmonic generation crystal located in a path between the pulse shaper and the detection device.

28. The system of claim 26 wherein the crystal is a thick crystal.

29. The system of claim 26 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of each of the pulses to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

71. The system of claim 20 wherein at least one of the pulses is of a duration less than about 50 femtoseconds.

72. The system of claim 20 wherein at least one of the pulses is of a duration less than about 11 femtoseconds.

25. A system comprising:

a laser beam pulse;

a pulse shaper operably varying the pulse;

an optic component operably receiving the pulse as shaped by the pulse shaper in a converging phase matching angle manner and

then causing the pulse to diverge into separate color frequencies;

a transmitting control unit;

multiple communications sources connected to and sending input signals to the transmitting control unit;

the transmitting control unit operably changing an aspect of the pulse shaper to encode multiple successive laser beam pulses in accordance with the input signals received from the communications sources and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

73. The system of claim 25 wherein the single laser beam pulse is encoded with the multiple communications routing addresses.

74. The system of claim 25 wherein the laser beam pulse is encoded by the pulse shaper with communications message data.

75. The system of claim 25 wherein the pulse is of a duration less than about 50 femtoseconds.

76. The system of claim 25 wherein the pulse is of a duration less than about 11 femtoseconds.

77. The system of claim 25 wherein the optic component is a crystal.

78. The system of claim 77 wherein the crystal is a second harmonic generation crystal located in a path after the pulse shaper.

79. The system of claim 77 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

30. A system comprising:

a laser beam pulse;

a pulse shaper operably varying the pulse;

an optic component operably receiving the pulse as shaped by the pulse shaper in a converging phase matching angle manner and then causing the pulse to diverge into separate color frequencies;

a communications transmitter assembly including a laser and the pulse shaper, the laser operably emitting the laser beam pulse;

a communications receiver assembly including the optic component and a detector;

the transmitter assembly operably sending encoded laser signals to the receiver assembly which operably decodes the laser signals in an asynchronous manner based on a predetermined decryption code; and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

80. The system of claim 30 wherein the pulse is of a duration less than about 50 femtoseconds.

81. The system of claim 30 wherein the pulse is of a duration less than about 11 femtoseconds.

82. The system of claim 30 wherein the optic component is a crystal.

83. The system of claim 82 wherein the crystal is a second harmonic generation crystal located in a path after the pulse shaper.

84. The system of claim 82 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

31. A system comprising:

a laser beam pulse;

a pulse shaper operably varying the pulse;

an optic component operably receiving the pulse as shaped by the pulse shaper in a converging phase matching angle manner and then causing the pulse to separate;

a fiber optic cable carrying the laser beam pulse from the pulse shaper and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

85. The system of claim 31 wherein the pulse is of a duration less than about 50 femtoseconds.

86. The system of claim 31 wherein the pulse is of a duration less than about 11 femtoseconds.

87. The system of claim 31 wherein the optic component is a crystal.

88. The system of claim 87 wherein the crystal is a second harmonic generation crystal located in a path after the pulse shaper.

89. The system of claim 87 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

119. The system of claim 31 further comprising:

the pulse shaper operably varying at least one characteristic of the pulse to include encoded communications data; and

a remotely located communications unencryptor operable to decode the varied pulse characteristic in an asynchronous manner.

120. The system of claim 119 wherein the optic component is a passive optic component associated with the unencryptor operably causing self-separation of the encoded pulse.

121. The system of claim 31 wherein the pulse is encoded to carry address routing information and the associated communications information.

122. The system of claim 31 wherein intrapulse interference causes self-routing and separated frequencies of the pulse corresponding to encoded individual address routing data.

123. The system of claim 31 wherein the pulse shaper is located in a communications transmitter.

32. A system comprising:

a laser operably emitting a laser beam pulse;

an optic operably causing phase modulation of the laser beam pulse;

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse; and

at least one unit operably receiving the phase modulated pulse, determining at least one of;

(a) the magnitude and (b) sign, of the phase modulation in the frequency domain of the pulse.

36. The system of claim 32 wherein the unit independently measures quadratic phase modulation from the shaped pulse independent of higher order phase modulations.

37. The system of claim 32 wherein the optic is a pulse shaper which introduces a known reference phase to the pulse so the unit can analyze an unknown phase in the pulse.

38. The system of claim 32 wherein the at least one unit includes a spectrometer.

39. The system of claim 32 further comprising a pulse shaper, wherein the unit includes a thick, second harmonic generation crystal and a measuring device.

40. The system of claim 32 wherein the at least one unit includes a controller operable to determine the quadratic phase modulation and automatically adjust a member associated with the laser to reduce quadratic chirp.

42. The system of claim 32 wherein a subsequent laser beam pulse is used for communicating data from a transmission source to a remotely located receiving source.

43. The system of claim 32 wherein both the magnitude and sign of the pulse are determined by the receiving unit.

33. A system comprising:

a laser operably emitting a laser beam pulse;

an optic operably causing phase modulation of the laser beam pulse;

a unit operably receiving the phase modulated pulse and determining at least one of;

(a) the magnitude and (b) sign, of the phase modulation in the frequency domain;

a controller calculating a distance from a component associated with the laser to the receiving unit being targeted, by determining the magnitude of the acquired second order phase modulation as the laser beam pulse travels through a fluid, and

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse.

34. The system of claim 33 wherein the fluid is water.

35. The system of claim 33 wherein the controller makes the distance calculation without a reflected signal from the receiving unit being targeted.

41. A system comprising:

a laser operably emitting a laser beam pulse;

an optic operably causing phase modulation of the laser beam pulse;

software instructions operably causing multiphoton intrapulse interference to be created in the laser beam pulse; and

a unit operably receiving the phase modulated pulse and determining at least one of;

(a) the magnitude and (b) sign, of the phase modulation in the frequency domain;

wherein at least a subsequent laser beam pulse is used for photodynamic therapy upon tissue.

90. The system of claim 41 wherein the pulse is of a duration less than about 50 femtoseconds, and both the magnitude and sign of the pulse are determined by the receiving unit.

91. The system of claim 41 wherein the pulse is of a duration less than about 11 femtoseconds.

92. The system of claim 41 wherein the optic is a crystal.

93. The system of claim 92 wherein the crystal is a second harmonic generation crystal located in a path between the pulse shaper and the receiving unit.

94. The system of claim 92 further comprising a lens located between the pulse shaper and the crystal, the lens causing the spectrum of the pulse to converge upon the crystal in a phase matching angle manner for subsequent dispersion and separation by the crystal across substantially the entire spectrum of the pulse.

44. A laser system comprising:

a laser beam pulse;

a pulse shaper operably varying a characteristic of the pulse; and

a device, including software instructions, operable to create multiphoton intrapulse interference in the pulse.

45. The system of claim 44 wherein the device causes the pulse to become self-switching when it undergoes a non-linear optical process.

46. The system of claim 45 wherein the non-linear optical process includes second harmonic generation.

47. The system of claim 45 wherein the non-linear optical process includes sum frequency generation.

48. The system of claim 45 wherein the non-linear optical process includes difference frequency generation.

49. The system of claim 45 wherein the non-linear optical process includes four-wave mixing.

50. The system of claim 44 wherein quadratic phase distortions are sensed and automatically minimized if present.

51. The system of claim 44 wherein phase modulation induced by an optical component is measured.

52. The system of claim 44 further comprising a detector operable to receive the shaped pulse.

53. The system of claim 52 wherein the detector includes a CCD camera.

54. The system of claim 52 wherein the detector includes an array of optical fibers connected to remote controllers.

95. The system of claim 44 wherein the pulse is of a duration less than about 50 femtoseconds.

96. The system of claim 44 wherein the pulse is of a duration less than about 11 femtoseconds.

113. The system of claim 44 wherein the device is a programmable controller and the software instructions of the controller operably vary the shape of subsequent pulses through automatic control of the pulse shaper.

114. The system of claim 44 wherein the shape imparted on the pulse by the pulse shaper is predetermined.

115. The system of claim 44 wherein the shape imparted on the pulse by the pulse shaper is automatically calculated by the device.

116. The system of claim 44 wherein the characteristic of the pulse is an order of multiphoton processes in the pulse.

117. The system of claim 44 wherein the device calculates a desirable function of phase versus frequency for the pulse shaper.

124. The system of claim 44 wherein the pulse shaper has a fixed pulse shaping configuration which is determined by an initial set up evaluation using the software instructions.

97. A laser system comprising:

a laser operably emitting a pulse; and

a unit operable to apply multiphoton intrapulse interference in the pulse, the unit further comprising a pulse shaper and software.

98. The system of claim 97 wherein the software causes the pulse shaper to operably vary the pulse.

100. The system of claim 97 further comprising a communications device using the pulse.

101. The system of claim 97 wherein the pulse is used in a photodynamic therapy device upon tissue.

102. The system of claim 97 wherein the pulse is used in an optical coherence tomography device.

103. The system of claim 97 wherein the pulse is used in a microscopy device on living tissue.

104. The system of claim 97 wherein the pulse is used for photochemistry control.

105. The system of claim 97 wherein two photon transitions in the pulse are achieved while three or greater photon transitions are substantially suppressed in the pulse.

106. The system of claim 97 further comprising a fiber optical cable carrying the multiphoton intrapulse interference-affected pulse.

107. The system of claim 97 wherein the unit further comprises:

a thin second harmonic generation crystal; and

a fixed mask, pulse shaper exhibiting a smooth function of phase versus frequency.

112. The system of claim 97 further comprising means for controlling photon transitions in the pulse.

125. The system of claim 97 wherein the pulse shaper has a fixed pulse shaping configuration which is determined by an initial set up evaluation using the software instructions.

99. A laser system comprising:

a laser pulse;

a controller, including a computer program, operably calculating distortions in the pulse; and

a pulse shaper operable to apply multiphoton intrapulse interference in the pulse based at least in part on the calculations by the computer program of the controller;

wherein the pulse has a duration of less than about 50 femtoseconds.

108. The system of claim 99 further comprising a spectrometer operably receiving at least a portion of the shaped pulse.

109. The system of claim 99 wherein the controller operably varies the shape of subsequent pulses through automatic control of the pulse shaper.

110. The system of claim 99 further comprising a communications device operably receiving the pulse.

111. The system of claim 99 wherein the pulse is used in at least one of:

(a) a medical treatment device and (b) a medical imaging device.

126. The system of claim 99 wherein the pulse shaper has a fixed pulse configuration which is determined by an initial set up evaluation using the computer program.