EP-4736282-A1 - EXTERNAL CAVITY LASER ASSEMBLY WITH STABLE OUTPUT FREQUENCY

Abstract

A laser assembly (10) that generates a first beam (40) includes an emitter (16), a transmission grating assembly (20), and a redirector assembly (22). The emitter (16) emits an emitter beam (16a) from a first facet (16c). The transmission grating assembly (20) is positioned in the path of the emitter beam (16a), and the transmission grating assembly (20) diffracts the emitter beam (16a) into the first beam (40) and a second beam (42) during transmission through the transmission grating assembly (20). The redirector assembly (22) receives the second beam (42) and directs a redirected beam (44) at the transmission grating assembly (20) to form an external cavity.

Inventors

• WHITMORE, Alexander, Jason
• PUSHKARSKY, MICHAEL
• MULKEY, Daniel
• LANOVAZ, Marcus
• KISHIMOTO, Carrie
• SCHALCH, Jacob
• WEIDA, MILES
• PRIEST, ALLEN

Assignees

• Daylight Solutions, Inc.

Dates

Publication Date

20260506

Application Date

20240621

Claims (20)

1. 1. A laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam, the transmission grating assembly diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly; and a redirector assembly that receives the second beam and directs a redirected beam at the transmission grating.
2. 2. The laser assembly of claim 1 wherein the transmission grating assembly diffracts the redirected beam into a redirected cavity beam during transmission through the transmission grating assembly that is directed to the first facet of the emitter.
3. 3. The laser assembly of any of claims 1 and 2 wherein the transmission grating assembly diffracts the redirected beam into a redirected output beam during transmission through the transmission grating assembly.
4. 4. The laser assembly of claim 1 wherein the redirector assembly includes a redirector and a redirector mover that selectively moves the redirector to selectively tune a center wavelength of the emitter beam.
5. 5. The laser assembly of claim 4 wherein the redirector mover includes a guide assembly that guides the movement of the redirector, and a redirector actuator assembly that moves the redirector.
6. 6. The laser assembly of claim 5 further wherein the guide assembly includes a flexure.
7. 7. The laser assembly of any of claims 5 and 6 wherein the redirector actuator assembly includes a piezoelectric actuator.
8. 8. The laser assembly of claim 4 further wherein the redirector mover selectively moves the redirector approximately about a selected pivot axis that allows for mode hop free tuning over a large spectral range.
9. 9. The laser assembly of claim 4 further comprising a system controller that selectively controls a current to the emitter to selectively tune the center wavelength of the emitter beam.
10. 10. The laser assembly of claim 1 wherein the first beam is a zeroth order diffraction of the emitter beam, and the second beam is a first order diffraction of the emitter beam.
11. 11 . The laser assembly of claim 1 wherein the emitter includes a second facet that forms a first cavity end of an external cavity, and the redirector assembly forms a second cavity end of the external cavity; and wherein the transmission grating is positioned the between cavity ends along an optical path of the external cavity and wherein the transmission grating functions as an output coupler.
12. 12. The laser assembly of claim 1 wherein the redirector assembly includes a retroreflector or porro prism.
13. 13. The laser assembly of claim 1 further comprising a beam shaper positioned in the path of the first beam that shapes the first beam.
14. 14. The laser assembly of claim 1 further comprising an isolator positioned in the path of the first beam, wherein the isolator attenuates light from being directed back at the transmission grating.
15. 15. The laser assembly of claim 1 further comprising a pointer adjuster assembly that adjusts the pointing of the first beam.
16. 16. The laser assembly of claim 15 wherein the pointer adjuster assembly includes a first wedged window.
17. 17. The laser assembly of claim 16 wherein the pointer adjuster assembly includes a second wedged window.
18. 18. The laser assembly of claim 1 further comprising a polarization adjuster assembly that adjusts the polarization of the first beam.
19. 19. The laser assembly of claim 18 wherein the polarization adjuster assembly includes a first waveplate.
20. 20. The laser assembly of claim 19 wherein the polarization adjuster assembly includes a second waveplate.

Description

EXTERNAL CAVITY LASER ASSEMBLY WITH STABLE OUTPUT FREQUENCY RELATED APPLICATION [0001] As far as permitted, the contents of (i) U.S. Patent Application No: 63/510,619, filed on June 27, 2023, and entitled “External Cavity Laser Assembly With Stable Output Frequency”, (ii) U.S. Patent Application No: 63/624,691 , filed on January 24, 2024, and entitled “External Cavity Laser Assembly With Stable Output Frequency”, and (iii) U.S. Patent Application No: 63/625,833, filed on January 26, 2024, and entitled “External Cavity Laser Assembly With Stable Output Frequency” are incorporated herein by reference. BACKGROUND [0002] Laser assemblies can be used in many fields such as, laboratories, Lidar, medical diagnostics, pollution monitoring, leak detection, analytical instruments, homeland security, aerospace, remote chemical sensing, industrial process control, and jamming of heat-seeking missiles. One type of laser assembly is an external cavity laser diode assembly. Unfortunately, lab grade external cavity laser diode assemblies are large, expensive, have inaccurate tuning, have inaccurate pointing, and have a free running linewidth that is highly susceptible to acoustics and vibrations. [0003] Manufacturers are always searching for ways to reduce size, reduce cost, improve tuning accuracy, improve pointing, improve running linewidth stability, improve beam quality, and improve power output of these laser assemblies. SUMMARY [0004] One implementation is directed to a laser assembly that generates a first beam. The laser assembly can include an emitter, a transmission grating assembly, and a redirector assembly. The emitter emits an emitter beam from a first facet. The transmission grating assembly is positioned in the path of the emitter beam, and the transmission grating assembly diffracts the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly. The redirector assembly that receives the second beam and directs a redirected beam at the transmission grating assembly. [0005] One implementation is directed to a laser assembly that generates a first beam. The laser assembly can include an emitter, a transmission grating assembly, and a redirector assembly. The emitter emits an emitter beam from a first facet. The transmission grating assembly is positioned in the path of the emitter beam, and the transmission grating assembly diffracts the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly. The redirector assembly receives the second beam and directs a redirected beam at the transmission grating assembly. [0006] The transmission grating assembly diffracts the redirected beam into a redirected cavity beam during transmission through the transmission grating assembly that is directed to the first facet of the emitter. Further, the transmission grating assembly can diffract the redirected beam into a redirected output beam during transmission through the transmission grating assembly. [0007] The redirector assembly can include a redirector and a redirector mover that selectively moves the redirector to selectively tune a center wavelength of the emitter beam. The redirector mover can include a guide assembly that guides the movement of the redirector, and a redirector actuator assembly that moves the redirector. The guide assembly can be a flexure. The redirector actuator assembly can include a piezoelectric actuator. [0008] In one design, the redirector mover selectively moves the redirector approximately about a selected pivot axis that allows for mode hop free tuning over a large spectral range. [0009] Additionally, the laser assembly can include a system controller that selectively controls a current to the emitter to selectively tune the center wavelength of the emitter beam. [0010] The emitter includes a second facet that forms a first cavity end of an external cavity, and the redirector assembly forms a second cavity end of the external cavity. In this design, the transmission grating is positioned the between cavity ends along an optical path of the external cavity, and the transmission grating functions as an output coupler. The redirector assembly can include a retroreflector or porro prism. [0011] Additionally, in any of the designs provided herein, the laser assembly can include one or more of: (i) a beam shaper positioned in the path of the first beam that shapes the first beam; (ii) an isolator positioned in the path of the first beam, wherein the isolator attenuates light from being directed back at the transmission grating (e.g., set to the fundamental wavelength of the external cavity); (iii) a pointer adjuster assembly that adjusts the pointing of the first beam; (iv) a polarization adjuster assembly that adjusts the polarization of the first beam; (v) a coupling lens assembly that focuses the first beam onto a lens focal point; and/or (vi) a non-linear crystal, such as a secon