All-optical spatial light modulators

Patent metadata

Field	Value
Publication number	US-11022826-B2
Application number	US-202016872731-A
Country	US
Kind code	B2
Filing date	May 12, 2020
Priority date	Jul 12, 2019
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A spatial light modulator (SLM) comprised of a 2D array of optically-controlled semiconductor nanocavities can have a fast modulation rate, small pixel pitch, low pixel tuning energy, and millions of pixels. Incoherent pump light from a control projector tunes each PhC cavity via the free-carrier dispersion effect, thereby modulating the coherent probe field emitted from the cavity array. The use of high-Q/V semiconductor cavities enables energy-efficient all-optical control and eliminates the need for individual tuning elements, which degrade the performance and limit the size of the optical surface. Using this technique, an SLM with 106 pixels, micron-order pixel pitch, and GHz-order refresh rates could be realized with less than 1 W of pump power.

First claim

The invention claimed is:

1. A spatial light modulator comprising:
a layer patterned with a two-dimensional array of semiconductor cavities, the two-dimensional array of semiconductor cavities each scattering signal light at a resonant wavelength;
a two-dimensional array of light-emitting diodes (LEDs), in optical communication with the two-dimensional array of semiconductor cavities, to tune the resonant wavelength of at least one semiconductor cavity in the two-dimensional array of semiconductor cavities via optical free carrier injection;
a control layer, operably coupled to the two-dimensional array of LEDs, to modulate LEDs in the two-dimensional array of LEDs at a rate of at least 1 GHz; and
a waveguide layer, in optical communication with the two-dimensional array of LEDs and the two-dimensional array of semiconductor cavities, to image pump signals emitted by the two-dimensional array of LEDs onto the two-dimensional array of semiconductor cavities.

2. The spatial light modulator of claim 1 , wherein the semiconductor layer comprises silicon.

3. The spatial light modulator of claim 1 , wherein each semiconductor cavity in the two-dimensional array of semiconductor cavities has a quality factor Q of at least 1000.

4. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities is comprised of H1 photonic crystal cavities.

5. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities is comprised of L4/3 photonic crystal cavities.

6. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities is comprised of micropillar cavities.

7. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities has a pitch of about half the resonant wavelength to about the resonant wavelength.

8. The spatial light modulator of claim 1 , wherein the pump signals emitted by the two-dimensional array of LEDs are at a wavelength of less than 500 nm and the signal light is at a wavelength of more than 500 nm.

9. The spatial light modulator of claim 1 , further comprising:
a signal light waveguide layer, in optical communication with the semiconductor layer, to guide the signal light to the at least one semiconductor cavity.

10. The spatial light modulator of claim 9 , further comprising:
a signal light source, in optical communication with the signal waveguide layer, to launch the signal light into the signal waveguide layer.

11. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities comprises a surface defined by a photonic crystal slab guided mode resonator.

12. The spatial light modulator of claim 1 , wherein the two-dimensional array of semiconductor cavities includes a wavelength-scale patterned semiconductor slab.

13. The spatial light modulator of claim 12 , wherein the two-dimensional array of semiconductor cavities supports a spatially distributed resonant mode.

14. The spatial light modulator of claim 1 , wherein a free carrier lifetime of the two-dimensional array of semiconductor cavities is about 100 ps or less.

15. The spatial light modulator of claim 1 , wherein a free carrier lifetime of the two-dimensional array of semiconductor cavities is about 1 ns or more.

Assignees

• Massachusetts Inst Technology

Inventors

• Panuski Christopher Louis
• Englund Dirk Robert

Classifications

• G02F2203/12

  spatial light modulator · CPC title

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title

• G02F1/015

  based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction (G02F1/03 takes precedence) · CPC title

• G02F2203/15

  involving resonance effects, e.g. resonantly enhanced interaction · CPC title

• G02F2202/32

  Photonic crystals · CPC title