Liquid crystal waveguide with active incoupling

Patent metadata

Field	Value
Publication number	US-10976579-B2
Application number	US-201816059731-A
Country	US
Kind code	B2
Filing date	Aug 9, 2018
Priority date	Aug 9, 2018
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

A liquid crystal waveguide (LCW) can include actively controlled incoupling of light into a LCW, such as by using a voltage-controlled electrode to actively vary a property of an LC material arranged to affect the incoupling of light into the LCW. Actively varying light incoupling into the LCW can be used, for example, such as for calibration or compensation or to provide closed-loop feedback such as to stabilize the amount of light into the LCW while accommodating or reducing sensitivity of the LCW to variations in one or more of: input laser light incidence angle, input laser wavelength, LCW or input laser temperature, input laser optical power level, or the like. This can advantageously help improve or maximize light incoupling efficiency, which can improve performance and robustness of the LCW under actual operating conditions. The LCW can be used for, among other things, beamsteering in in-plane and out-of-plane directions.

First claim

The claimed invention is:

1. A Liquid Crystal Waveguide (LCW) system with controlled incoupling from air of incident laser light, the system comprising:
a Liquid Crystal Waveguide (LCW), including:
a core, arranged to receive light provided at a light input for communication toward a light output;
a light-incoupling control electrode; and
a Liquid Crystal (LC) material, arranged to be controlled by a control signal applied to the light-incoupling control electrode to vary a property of the LC material to adjust an incoupling from air of light incident from an input laser into the core of the LCW.

2. The LCW system of claim 1 , comprising a controller circuit, configured to vary the control signal applied to the light-incoupling control electrode to vary a property of the LC material to adjust an incoupling of light into the core of the LCW to accommodate a variation in at least one of input laser light incidence angle, input laser wavelength, input laser position, LCW or input laser temperature, or input laser optical power level.

3. The LCW system of claim 1 , further including a light detector sensor, coupled to an input of the controller circuit to apply the control signal to the light-incoupling control electrode to adjust incoupling of light into the core in response to light detected by the light detector sensor.

4. The LCW system of claim 3 , wherein:
the Liquid Crystal Waveguide (LCW) includes a substrate, arranged to receive light for input into the LCW; and
the light detector sensor is arranged to detect light input into the substrate without being received by the core.

5. The LCW system of claim 3 , wherein the light detector sensor is arranged to detect light guided and output by the LCW waveguide.

6. The LCW system of claim 1 , wherein:
the Liquid Crystal Waveguide (LCW) includes a subcladding arranged with respect to the core to tend to confine light within the core for communication toward the light output; and
wherein at least one of the subcladding or the LC material includes a tapered cross-section region providing a path via which light input from the substrate passes in being communicated to the core.

7. The LCW system of claim 1 , wherein the Liquid Crystal Waveguide (LCW) includes at least one of: a substrate, arranged to receive light for input into the LCW, or a subcladding, arranged with respect to the core to tend to confine light within the core for communication toward the light output; and
wherein the LCW system includes a step-coupler including an input region providing higher relative efficiency incoupling of light into the core, and a downstream optical isolation region along a portion of the core for tending to confine light in the core for communication toward the LCW output, wherein the optical isolation region includes a lower relative efficiency incoupling than the input region.

8. The LCW system of claim 7 , wherein the optical isolation region is provided by a subcladding region having a larger cross-section than a subcladding in the input region of the step-coupler.

9. The LCW system of claim 7 , wherein the optical isolation region is provided by a fill region defined by the substrate, the fill region including a lower index of refraction material than a material of the substrate.

10. The LCW system of claim 1 , including a diffractive grating located to provide at least partially diffractive incoupling of light into the core.

11. The LCW system of claim 1 , comprising:
a controller circuit, configured to vary the control signal applied to the light-incoupling control electrode to vary a property of the LC material to adjust an incoupling of light into the core of the LCW; and
a temperature sensor, coupled to an input of the controller circuit to apply the control signal to the light-incoupling control electrode to adjust incoupling of light into the core in response to an indication of temperature detected by the temperature sensor.

12. The LCW system of claim 1 , comprising:
a controller circuit, configured to vary the control signal applied to the light-incoupling control electrode to vary a property of the LC material to adjust an incoupling of light into the core of the LCW; and
wherein the controller circuit is configured for dithering light incoupled to the core for providing a signature to a lock-in amplifier.

13. The LCW system of claim 1 , wherein the Liquid Crystal Waveguide (LCW), further comprises:
a substrate, arranged to receive light for input into the LCW; and
a subcladding, arranged with respect to the core to tend to confine light within the core for communication toward the light output.

14. A method of using a Liquid Crystal Waveguide (LCW) and controlling incoupling of light into the LCW, the method comprising:
receiving light for input into the LCW; and
controlling incoupling of light from air, incident from a laser beam, into the LCW, including by applying a control signal to vary a property of a Liquid Crystal (LC) material to adjust an incoupling of light from air into the LCW.

15. The method of claim 14 , comprising:
detecting an indication of light incoupling into the core; and
using the indication of light incoupling into the core as a feedback signal for the controlling incoupling of light into a core of the LCW.

16. The method of claim 15 , wherein the detecting the indication of light incoupling into the core includes detecting a light reflected without being incoupled into the core.

17. The method of claim 15 , wherein the detecting the indication of light incoupling into the core includes detecting an indication of light output from the LCW.

18. The method of claim 15 , comprising adjusting at least one of a laser wavelength, power, or incidence angle onto the LCW in response to the indication of light incoupling into the core.

19. The method of claim 14 , wherein controlling incoupling of light into a core of the LCW includes controlling a path through a tapered cross-sectional material.

20. The method of claim 14 , wherein controlling incoupling of light into the core includes varying a control signal applied to a light-incoupling control electrode to vary a property of the LC material to adjust an incoupling of light into the core of the LCW to accommodate a variation in at least one of input laser light incidence angle, input laser wavelength, LCW or input laser temperature, or input laser optical power level.

21. The method of claim 14 , comprising controlling incoupling of light into the core in response to a detected temperature of at least one of the LCW or the laser.

22. The method of claim 14 , wherein controlling incoupling of light into the core includes dithering light power through the LCW.

23. An apparatus for controlling incoupling of light into a Liquid Crystal Waveguide (LCW), the apparatus comprising:
means for receiving light for input into the LCW; and
means for controlling incoupling of light from air, incident from a laser beam, into the LCW, including by applying a control signal to vary a property of a Liquid Crystal (LC) material to adjust an incoupling of light from air into the LCW.

24. The apparatus of claim 23 , comprising:
means for detecting an indication of light incoupling into the core; and
means for using the indication of light incoupling into the core as a feedback signal for the controlling incoupling of light into a core of the LCW.

Assignees

• Analog Devices Inc

Inventors

• Ziemkiewicz Michael
• Davis Scott Robert
• Rommel Scott D
• Luey Benjamin
• Anderson Michael Howard
• Gann Derek

Classifications

• G02B6/126

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G02F1/011

  in optical waveguides, not otherwise provided for in this subclass · CPC title

• G02F1/1326 Primary

  Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides · CPC title

• G02F2201/302

  grating coupler · CPC title

• G02F1/133371

  Cells with varying thickness of the liquid crystal layer · CPC title