Laser illumination systems and methods for dual-excitation wavelength non-linear optical microscopy and micro-spectroscopy systems

• US 9,104,030 B2
• Filed: 06/05/2014
• Issued: 08/11/2015
• Est. Priority Date: 01/17/2012
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation), Arizona Board of Regents (University of Arizona)
• Inventors: Kieu, Khanh, Peyghambarian, Nasser, Freudiger, Christian W., Fu, Dan, Xie, Xiaoling Sunney
• Primary Examiner(s): Petkovsek, Daniel
• Application Number:
  US14/297,082
• Publication Number:
  US 20140285873A1
• Time in Patent Office: 432 Days
• Field of Search: 359326-332, 372/25, 356/301, 356/337, 356/342
• US Class Current: 1/1
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/653 Coherent methods [CARS]
• CPC Class Codes: G01N 2021/655 Stimulated Raman
• CPC Class Codes: G02B 21/002 Scanning microscopes scanning near field optical microscopes G01Q60/18
• CPC Class Codes: G02B 21/008 Details of detection or image processing, including general computer control
• CPC Class Codes: G02B 21/16 adapted for ultraviolet illumination ; Fluorescence microscopes G02B21/0076 takes precedence
• CPC Class Codes: G02B 2207/114 Two photon or multiphoton effect
• CPC Class Codes: G02F 1/353 Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
• CPC Class Codes: G02F 1/354 Third or higher harmonic generation
• CPC Class Codes: G02F 1/37 for second-harmonic generation G02F1/3532 takes precedence
• 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 3/0092 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 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06791 Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/10023 by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/1118 Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2391 : emitting at different wavelengths

Abstract

An illumination system is disclosed for providing dual-excitation wavelength illumination for non-linear optical microscopy and micro-spectroscopy. The illumination system includes a laser system, an optical splitting means, a frequency shifting system, and a picosecond amplifier system. The laser system includes a laser for providing a first train of pulses at a center optical frequency ω₁. The optical splitting means divides the first train of pulses at the center optical frequency ω₁ into two trains of pulses. The frequency shifting system shifts the optical frequency of one of the two trains of pulses to provide a frequency shifted train of pulses. The picosecond amplifier system amplifies the frequency shifted train of pulses to provide an amplified frequency-shifted train of pulses having a pulse duration of at least 0.5 picoseconds.

Claims

1. An illumination system for providing dual-excitation wavelength illumination for non-linear optical microscopy and micro-spectroscopy, said illumination system comprising:

a laser system including a laser for providing a first train of pulses at a center optical frequency ω

₁;

an optical splitting means for dividing the first train of pulses at the center optical frequency ω

₁ into a first split train of pulses and a second split train of pulses;

a frequency shifting system for shifting the optical frequency of the first split train of pulses to provide a frequency shifted train of pulses;

an amplifier system for amplifying the frequency-shifted train of pulses to provide an amplified frequency-shifted train of pulses;

combining means for combining the amplified frequency-shifted train of pulses with the second split trains of pulses to provide the amplified frequency-shifted train of pulses and the second split trains of pulses as a collinear train of laser pulses for the dual-excitation wavelength illumination; and

adjustment means for adjusting a time delay between the amplified frequency-shifted train of pulses and the second split train of pulses.

2. The illumination system as claimed in claim 1, wherein said frequency shifting system includes a highly non-linear fiber.

3. The illumination system as claimed in claim 1, wherein said amplifier system includes a narrowband filter.

4. The illumination system as claimed in claim 1, wherein said amplifier system includes a plurality of amplifier systems in series.

5. The illumination system as claimed in claim 1, wherein said amplifier system includes a chirped amplifier system.

6. The illumination system as claimed in claim 1, wherein said chirped amplifier system includes a chirp unit and an amplifier.

7. The illumination system as claimed in claim 1, wherein said chirped amplifier system further includes a broadband filter.

8. The illumination system as claimed in claim 1, wherein said system further includes a chirp means for adjusting the chirp of the second split train of pulses from the optical splitting means.

9. The illumination system as claimed in claim 1, wherein said system further includes a second amplifier system for amplifying the second split train of pulses.

10. The illumination system as claimed in claim 9, wherein an output of the second laser amplifier system is frequency doubled (SHG) or tripled (THG).

11. The illumination system as claimed in claim 9, wherein said amplifier system is one of an Erbium fiber amplifier, a Ytterbium fiber amplifier, a Thulium fiber amplifier, and a Holmium fiber amplifier.

12. The illumination system as claimed in claim 1, wherein said laser system is one of a Ytterbium fiber laser and an Erbium fiber laser.

13. The illumination system as claimed in claim 1, wherein said laser system is a Titanium Sapphire laser.

14. The illumination system as claimed in claim 1, wherein said amplifier system is one of an Erbium fiber amplifier, a Ytterbium fiber amplifier, a Thulium fiber amplifier, and a Holmium fiber amplifier.

15. The illumination system as claimed in claim 1, wherein the output of the amplifier system is frequency doubled (SHG) or tripled (THG).

16. The illumination system as claimed in claim 1, wherein the second split train of pulses from the optical splitting means is frequency doubled (SHG) or tripled (THG).

17. The illumination system as claimed in claim 1, wherein said illumination system is provided in a dual-excitation wavelength nonlinear microscopy or micro-spectroscopy system.

18. The dual-excitation wavelength nonlinear microscopy system of claim 17, wherein said dual-excitation wavelength nonlinear microscopy system includes balanced detectors.

19. The dual-excitation wavelength nonlinear microscopy system of claim 17, wherein said dual-excitation wavelength nonlinear microscopy system performs Coherent Anti-Stoke Raman Scattering microscopy or micro-spectroscopy.

20. The dual-excitation wavelength nonlinear microscopy system of claim 17, wherein said dual-excitation wavelength nonlinear microscopy system performs Stimulated Raman Scattering microscopy or micro-spectroscopy.

21. The dual-excitation wavelength nonlinear microscopy system of claim 17, wherein said dual-excitation wavelength nonlinear microscopy system performs two-color two-photon microscopy or micro-spectroscopy.