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US-12625306-B2 - Thin film narrow bandwidth transmission filter for optical emitters

US12625306B2US 12625306 B2US12625306 B2US 12625306B2US-12625306-B2

Abstract

In some implementations, an optical system includes an optical emitter, a locking apparatus, wherein the locking apparatus comprises a narrow bandwidth transmission filter (NBTF) and a partial reflection surface, wherein the locking apparatus is aligned to an optical output of the optical emitter, and wherein the locking apparatus is configured to provide optical feedback to the optical emitter.

Inventors

  • CAILIN WEI
  • Jihua Du
  • Prasad Yalamanchili

Assignees

  • LUMENTUM OPERATIONS LLC

Dates

Publication Date
20260512
Application Date
20221219

Claims (20)

  1. 1 . An optical system, comprising: an optical emitter, a locking apparatus, wherein the locking apparatus comprises: a narrow bandwidth transmission filter (NBTF); a partial reflection surface, wherein the locking apparatus is aligned to an optical output of the optical emitter, and wherein the locking apparatus is configured to provide optical feedback to the optical emitter; and a fast axis collimator (FAC) and a slow axis collimator (SAC) aligned to an optical path of the optical emitter, the partial reflection surface, and the NBTF, wherein the partial reflection surface and the SAC are implemented in a single optical element.
  2. 2 . The optical system of claim 1 , wherein the optical emitter is a single-mode laser or a multi-mode laser.
  3. 3 . The optical system of claim 1 , wherein the NBTF and the partial reflection surface are implemented in separate, discrete optical elements and optically aligned to each other.
  4. 4 . The optical system of claim 1 , wherein the NBTF is angled relative to an optical path associated with the optical emitter.
  5. 5 . The optical system of claim 1 , wherein the NBTF is disposed in an optical path between the SAC and the FAC or between the SAC and the partial reflection surface.
  6. 6 . The optical system of claim 1 , wherein the NBTF has a transmissivity greater than a threshold at a single continuous wavelength range.
  7. 7 . An optical device, comprising: a locking apparatus, wherein the locking apparatus comprises: a narrow bandwidth transmission filter (NBTF); a partial reflection surface, wherein the locking apparatus is configured to provide optical feedback; and a fast axis collimator (FAC) and a slow axis collimator (SAC) aligned to an optical path of an optical emitter, the partial reflection surface, and the NBTF, wherein the partial reflection surface and the SAC are implemented in a single optical element.
  8. 8 . The optical device of claim 7 , further comprising the optical emitter.
  9. 9 . The optical device of claim 7 , wherein the optical emitter is a single-mode laser or a multi-mode laser.
  10. 10 . The optical device of claim 7 , wherein the NBTF has a transmissivity greater than a threshold at a single continuous wavelength range.
  11. 11 . The optical device of claim 7 , wherein the NBTF has a transmissivity greater than a threshold at a first wavelength range and a second wavelength range, the first wavelength range and the second wavelength range being different wavelength ranges.
  12. 12 . The optical device of claim 11 , further comprising: a set of emitters including a first emitter associated with emitting an optical beam in the first wavelength range and a second emitter associated with emitting the optical beam in the second wavelength range.
  13. 13 . The optical device of claim 12 , wherein the NBTF is optically aligned to a first optical element for the first wavelength range and a second optical element for the second wavelength range.
  14. 14 . The optical device of claim 7 , wherein the optical emitter is configured to emit an optical beam, the optical emitter being aligned to the NBTF and the partial reflection surface.
  15. 15 . A device, comprising: a locking apparatus, wherein the locking apparatus comprises: a narrow bandwidth transmission filter (NBTF); a partial reflection surface, wherein the locking apparatus is configured to provide feedback to an optical emitter; and a fast axis collimator (FAC) and a slow axis collimator (SAC) aligned to an optical path of the optical emitter, the partial reflection surface, and the NBTF, wherein the partial reflection surface and the SAC are implemented in a single optical element.
  16. 16 . The device of claim 15 , further comprising the optical emitter.
  17. 17 . The device of claim 15 , wherein the optical emitter is a single-mode laser or a multi-mode laser.
  18. 18 . The device of claim 15 , wherein the NBTF and the partial reflection surface are implemented in separate, discrete optical elements and optically aligned to each other.
  19. 19 . The device of claim 15 , further comprising: the optical emitter to emit an optical beam, the optical emitter being aligned to the NBTF and the partial reflection surface.
  20. 20 . The device of claim 19 , wherein the NBTF is a first NBTF having a first transmission wavelength and the optical emitter is a first optical emitter associated with emitting at the first transmission wavelength, and further comprising: a second NBTF having a second transmission wavelength; and a second optical emitter associated with emitting at the second transmission wavelength, wherein the first optical emitter is aligned to the first NBTF and the second optical emitter is aligned to the second NBTF.

Description

CROSS-REFERENCE TO RELATED APPLICATION This patent application claims priority to U.S. Provisional Patent Application No. 63/383,818, filed on Nov. 15, 2022, and entitled “THIN FILM NARROW BANDWIDTH TRANSMISSION FILTER.” The disclosure of the prior application is considered part of and is incorporated by reference into this patent application. TECHNICAL FIELD The present disclosure relates generally to optical filters and to thin film narrow bandwidth transmission filters for optical emitters. BACKGROUND In optical communications systems, a wavelength locked pump laser may be included as a component in a fiber amplifier module. For a single-mode wavelength locked pump laser system, a fiber Bragg grating (FBG) may be used as a wavelength selective reflective filter at an output fiber. The FBG may provide optical feedback to an optical emitter. Alternatively, a distributed feedback (DFB) diode chip may have a distributed grating which provides optical feedback to an optical emitter. For a multi-mode wavelength locked pump laser system, a volume Bragg grating (VBG) may be used to provide optical feedback for locking of an optical emitter. SUMMARY In some implementations, an optical system includes an optical emitter, a locking apparatus, wherein the locking apparatus includes a narrow bandwidth transmission filter (NBTF); and a partial reflection surface, wherein the locking apparatus is aligned to an optical output of the optical emitter, and wherein the locking apparatus is configured to provide optical feedback to the optical emitter. In some implementations, an optical device includes a locking apparatus, wherein the locking apparatus includes an NBTF; and a partial reflection surface, wherein the NBTF and the partial reflection surface are implemented on different surfaces of a single optical element, and wherein the locking apparatus is configured to provide optical feedback. In some implementations, an optical device includes a locking apparatus, wherein the locking apparatus includes an NBTF; and a partial reflection surface, wherein the NBTF is implemented on a first optical element and the partial reflection surface is implemented on a second optical element, the first optical element and the second optical element being separated by free space, and wherein the locking apparatus is configured to provide feedback. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1C are diagrams of examples associated with thin film narrow bandwidth transmission filters for optical emitters. FIG. 2 is a diagram of an example associated with thin film narrow bandwidth transmission filters for optical emitters. FIGS. 3A-3B are diagrams of examples associated with thin film narrow bandwidth transmission filters for optical emitters. DETAILED DESCRIPTION The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. Optical communication systems include optical emitters to emit optical beams. For example, a fiber amplifier node of an optical communication system may include a wavelength locked pump laser, such as a single-mode wavelength locked pump laser or a multi-mode wavelength locked pump laser. For example, a wavelength selective reflective filter, such as a fiber Bragg grating (FBG), may provide optical feedback for control of a single-mode wavelength locked pump laser. However, use of an FBG may be limited to fiber amplifiers that have fiber pigtails, which may prevent use of free space optics. Moreover, the FBG may be limited to structures where the fiber pigtails have coils with relatively large radii. In another example, a distributed grating on a distributed feedback (DFB) diode chip may provide feedback, which may influence the wavelength of a single-mode wavelength locked pump laser of the DFB diode chip However, DFB diode chips may experience wavelength drift at different ranges of operating drive currents and temperature. Moreover, at higher power ranges, a DFB chip may show power ripple, which may negatively impact optical performance. In yet another example, a volume Bragg grating (VBG) can be used as a narrow bandwidth filter for locking of a multi-mode wavelength locked pump laser. However, VBGs may be difficult to manufacture and/or may be excessively costly. Accordingly, using VBGs may limit deployments of optical communications systems. Some implementations described herein provide a locking apparatus that includes a narrowband transmission filter (NBTF) on a first surface of an optical element and a partial reflection surface on a second surface of an optical element. For example, an optical system may include an optical emitter, an NBTF on a first optical element, and a partial reflection surface on a second optical element. Alternatively, the optical system may include an optical emitter and an optical element with an NBTF on a first side and a partial reflection surface on a s