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EP-4738728-A1 - INTEGRATED PRISM-CHIRPED VOLUME BRAGG GRATING FOR DISPERSION COMPENSATION

EP4738728A1EP 4738728 A1EP4738728 A1EP 4738728A1EP-4738728-A1

Abstract

Aspects of the disclosure are directed to a system for incorporating a CVBG (Chirped Volume Bragg Grating) into a prism to form a P-CVBG (Prism-Chirped Volume Bragg Grating) optical element for channel dispersion compensation. A prism region is configured to receive optical signals with multiple wavelengths and provide the wavelengths to the CVBG region by spatially separating the optical signals into various wavelengths. The CVBG region is configured to compensate for dispersion of the multiple wavelengths by reflecting the various wavelengths at different depths within the gratings of the CVBG region.

Inventors

  • WANG, LIMING
  • ZHOU, XIANG
  • LAM, CEDRIC FUNG

Assignees

  • Google LLC

Dates

Publication Date
20260506
Application Date
20250911

Claims (15)

  1. An optical element for channel dispersion compensation, comprising: a prism region configured to receive one or more optical signals having multiple wavelengths; and a chirped volume Bragg grating (CVBG) region formed within the prism region.
  2. The optical element of claim 1, wherein the prism region is further configured to separate the one or more optical signals into the multiple wavelengths.
  3. The optical element of claim 2, wherein the CVBG region is configured to: compensate for communication link dispersion of the multiple wavelengths, wherein compensating the communication link dispersion of the multiple wavelengths comprises dispersing the one or more signals using one or more gratings in the CVBG region.
  4. The optical element of claim 3, wherein the CVBG region is configured based on at least one parameter associated with at least one of polarities of dispersion, orders of dispersion, or passband characteristics.
  5. The optical element of claim 3, further comprising high-reflection (HR) coatings on a back surface of the CVBG region to provide reflection of non-dispersive signals.
  6. The optical element of claim 5, wherein the HR coatings are positioned on an incident surface of the optical element to fold the multiple wavelengths into one or more combined signals.
  7. The optical element of any one of claims 1 to 6, wherein the prism region and CVBG region are formed with matching angles; and/or wherein the CVBG region comprises one or more segments, each of the segments comprising a pattern of gratings, each of the pattern of gratings having a spatial chirp; and wherein each of the segments optionally has a different pattern of gratings.
  8. The optical element of any one of claims 1 to 7, wherein the CVBG region is a diffraction free region to limit dispersion for one or more of the multiple wavelengths.
  9. System for channel dispersion compensation, comprising: an optical transceiver configured to generate multiple dimensional optical signals, the optical transceiver comprising: one or more lasers; one or more photodetectors; and an optical element, comprising: an angled prism region configured to receive the optical signals having multiple wavelengths; and a chirped volume Bragg grating (CVBG) region formed with the angled prism region.
  10. The system of claim 9, wherein the CVBG region is configured to: disperse one or more of the optical signals using the one or more gratings to compensate for dispersion; and combine the dispersed signals with other dispersed signals.
  11. The system of claim 9 or claim 10, wherein the CVBG region comprises one or more segments, each of the segments comprising a pattern of gratings, each of the pattern of gratings having a spatial chirp.
  12. The system of claim 11, wherein each of the segments has a different pattern of gratings.
  13. The system of any one of claims 9 to 12, the CVBG region is configured based on at least one parameter associated with at least one of polarities of dispersion, orders of dispersion, or passband characteristics; and/or further comprising high-reflection (HR) coatings on a back surface of the CVBG region to limit additional dispersion; and wherein the HR coatings optionally are positioned on an incident surface of the optical element.
  14. The system of any one of claims 9 to 13, wherein the CVBG region is a diffraction free region to reduce additional dispersion; and/or further comprising multiple filters connected to the optical element.
  15. The system of any one of claims 10 to 14, further comprising a multiplexer optically coupled to the optical element to receive the combined dispersed signals.

Description

BACKGROUND Optical modulation is a technology in modem data communication networks, enabling transmission over single-mode fibers (SMFs) ranging from meters to thousands of kilometers. This modulation inherently broadens the spectrum of laser sources, distributing information across multiple light wavelengths or frequencies. The signal spectrum typically expands with increasing data rates. SMFs exhibit chromatic dispersion due to material properties and waveguide effects, causing different wavelengths to propagate at varying speeds. As an optical signal travels through the fiber, the total chromatic dispersion can alter optical pulse widths, leading to undesired mixing of pulse energies. This effect, known as intersymbol interference (ISI), can significantly degrade signal quality. Various techniques have been proposed to mitigate ISI, yet significant challenges remain unresolved. BRIEF SUMMARY Aspects of the disclosure are directed to a system for incorporating a chirped volume Bragg grating (CVBG) into a prism to form a Prism-CVBG (P-CVBG) optical element for channel dispersion compensation. A prism region is configured to receive optical signals with multiple wavelengths and provide the wavelengths to the CVBG region by spatially separating the optical signals into various wavelengths. The CVBG region is configured to compensate for dispersion of the multiple wavelengths by reflecting the various wavelengths at different depths within the gratings of the CVBG region. An aspect of the disclosure provides for an optical element for channel dispersion compensation, including: a prism region configured to receive one or more optical signals having multiple wavelengths; and a chirped volume Bragg grating (CVBG) region formed within the prism region. In an example, the prism region is further configured to separate the one or more optical signals into the multiple wavelengths. In another example, the CVBG region is configured to: compensate for communication link dispersion of the multiple wavelengths, wherein compensating the communication link dispersion of the multiple wavelengths includes dispersing the one or more signals using one or more gratings in the CVBG region. In yet another example, the CVBG region is configured based on at least one parameter associated with at least one of polarities of dispersion, orders of dispersion, or passband characteristics. In yet another example, the optical element for channel dispersion compensation includes high-reflection (HR) coatings on a back surface of the CVBG region to provide reflection of non-dispersive signals. In yet another example, the HR coatings are positioned on an incident surface of the optical element to fold the multiple wavelengths into one or more combined signals. In yet another example, the prism region and CVBG region are formed with matching angles. In yet another example, the CVBG region comprises one or more segments, each of the segments comprising a pattern of gratings, each of the pattern of gratings having a spatial chirp. In yet another example, each of the segments has a different pattern of gratings. In yet another example, the CVBG region is a diffraction free region to limit dispersion for one or more of the multiple wavelengths. In yet another example, the CVBG region comprises one or more segments, each of the segments comprising a pattern of gratings, each of the pattern of gratings having a spatial chirp. In yet another example, each of the segments has a different pattern of gratings. In yet another example, the CVBG region is a diffraction free region to limit dispersion for one or more of the multiple wavelengths. In yet another example, the CVBG region comprises one or more segments, each of the segments comprising a pattern of gratings, each of the pattern of gratings having a spatial chirp. In yet another example, each of the segments has a different pattern of gratings. In yet another example, the CVBG region is a diffraction free region to limit dispersion for one or more of the multiple wavelengths. In yet another example, the CVBG region is a diffraction free region to limit dispersion for one or more of the multiple wavelengths. Another aspect of the disclosure provides for a system for channel dispersion compensation, including: an optical transceiver configured to generate multiple dimensional optical signals, the optical transceiver comprising: one or more lasers; one or more photodetectors; and an optical element, including: an angled prism region configured to receive the optical signals having multiple wavelengths; and a chirped volume Bragg grating (CVBG) region formed with the angled prism region. In an example, the CVBG region is configured to: disperse one or more of the optical signals using the one or more gratings to compensate for dispersion; and combine the dispersed signals with other dispersed signals. In yet another example, the CVBG region includes one or more segments, each of the segments compr