# US 11,906,825 B2 · Leaky-wave spatial modulator with integrated photonic crystal for all-optical analog-to-digital converters

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- Number: US 11,906,825 B2
- Document ID: US11906825B2
- Status: Granted
- Kind: B2
- Application number: 17/060,095
- Filed: 2020-10-01
- Published: 2021-04-01
- Granted: 2024-02-20
- Earliest claimed: 2019-10-01
- Assignees: Drexel University
- Applicants: Drexel University
- Inventors: Afshin S. Daryoush; Kai Wei
- Web page: https://patentgrep.com/patent/US11906825B2

## CPC

- G02F 1/0356: {controlled by a high-frequency electromagnetic wave component in an electric waveguide structure}
- G02F 1/065: in an optical waveguide structure
- G02F 1/2955: {by controlled diffraction or phased-array beam steering (controlled diffraction for optical waveguide switching G02F1/313)}
- G02F 2201/126: push-pull
- G02F 2201/127: travelling wave
- G02F 2203/12: spatial light modulator
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

Performance improvement of an all-optical analog-to-digital converter (AOADC) addresses both RF and optical modeling of a leaky waveguide based optical spatial light modulator (SLM) using electro-optic (E-O) material. The E-O polymer provides improved sensitivity for SLM and achieves a broader bandwidth due to better velocity matching between RF and optical waves.

## Claims

### Claim 1

A spatial light modulator (SLM) device within an all-optical analog to digital converter (AOADC) comprising:
a first radio frequency (RF) electrode;
a second RF electrode positioned in-plane and adjacent to the first RF electrode; an integrated electro-optic (E-O) polymer based optical waveguide positioned in-plane and sandwiched between the first RF electrode and the second RF electrode, wherein the integrated E-O polymer based optical waveguide is integrated with a photonic crystal (PhC) layer separated from the integrated E-O polymer based optical waveguide by a buffer layer defined by the first RF electrode and the second RF electrode such that the PhC layer is offset transversely with respect to the first RF electrode, the second RF electrode, and the integrated E-O polymer based optical waveguide to form a leaky waveguide structure that re-directs light to form the SLM, wherein a leaky wave exit angle from the integrated E-O polymer based optical waveguide is configured to be controlled by an RF signal applied to the leaky waveguide structure, and wherein the applied RF signal is quantized at discrete time intervals based on a sampling rate of the applied RF signal.

### Claim 2 (depends on 1)

The SLM of claim 1, wherein the integrated E-O polymer based optical waveguide is compatible with Si-Photonics.

### Claim 3 (depends on 1)

The SLM of claim 1, wherein DC contacts rendering realization of a lowpass filter are used for poling of the integrated E-O polymer based optical waveguide.

### Claim 4 (depends on 1)

The SLM of claim 1, wherein a superstrate material prism is comprised in the leaky waveguide structure.

### Claim 5 (depends on 1)

The SLM of claim 1, wherein the applied RF signal causes a change in a leakage angle of an optical wave in a superstrate.

### Claim 6 (depends on 1)

The SLM of claim 1, wherein a travelling wave push-pull topology of the RF electrodes provides a broad bandwidth of the RF modulated SLM.

### Claim 7 (depends on 1)

The SLM of claim 1, wherein the RF signal is a voltage applied to push-pull electrodes.

### Claim 8 (depends on 1)

The SLM of claim 1, wherein a gap between push-pull electrodes is configured to control an RF electric field.

### Claim 9 (depends on 1)

The SLM of claim 1, wherein an applied RF electric field changes an index of refraction due to the Pockels effect.

### Claim 10 (depends on 1)

The SLM of claim 1, wherein a change in an index of refraction in the optical waveguide adjusts an exit angle from the optical waveguide based on a dispersion diagram and the Snell's law.

### Claim 11 (depends on 1)

The SLM of claim 1, wherein the PhC layer is configured to decrease a wave velocity through the integrated E-O polymer based optical waveguide.

### Claim 12 (depends on 11)

The SLM of claim 11, wherein the PhC layer is configured to influence an effective group index at an operating optical wavelength.

### Claim 13 (depends on 11)

The SLM of claim 11, wherein SLM sensitivity is configured to be controlled by the PhC layer integrated with the buffer layer.

### Claim 14 (depends on 1)

The SLM of claim 1, wherein optical leakage of the leaky waveguide structure is configured to be controlled by adjusting an applied electric field in a gap of a push-pull travelling wave structure.