# US 2020/0400883 A1 · Photonic integrated circuit with encapsulated reference arm

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2020/0400883 A1
- Document ID: US20200400883A1
- Status: Published application
- Kind: A1
- Application number: 16/903,327
- Filed: 2020-06-16
- Published: 2020-12-24
- Earliest claimed: 2019-06-21
- Assignees: Commissariat A L'energie Atomique Et Aux Energies Alternatives; Aryballe
- Applicants: Commissariat A L'energie Atomique Et Aux Energies Alternatives; Aryballe Technologies
- Inventors: Loïc LAPLATINE; Mathieu DUPOY; Maryse FOURNIER; Pierre LABEYE; Thierry LIVACHE; Cyril HERRIER
- Web page: https://patentgrep.com/patent/US20200400883A1

## CPC

- G01N 21/7703: {using reagent-clad optical fibres or optical waveguides (using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B)}
- G01N 21/41: Refractivity; Phase-affecting properties, e.g. optical path length (G01N21/21 takes precedence)
- G01N 21/45: using interferometric methods; using Schlieren methods
- G01N 2021/458: {using interferential sensor, e.g. sensor fibre, possibly on optical waveguide}
- G01N 2021/7779: {interferometric}
- G01N 2201/08: Optical fibres; light guides
- G01N 2201/0873: Using optically integrated constructions
- G02B 6/122: Basic optical elements, e.g. light-guiding paths
- G02B 6/124: Geodesic lenses or integrated gratings
- G02B 2006/12107: {Grating}
- G02B 2006/12138: {Sensor}
- G02B 2006/1215: {Splitter}
- G02B 2006/12159: {Interferometer}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A photonic integrated circuit for an interferometric sensor includes a first waveguide called sensitive arm wherein a first portion of the light radiation is propagated, the sensitive arm being exposed to a first ambient medium and to at least one compound to be detected inducing a modification of the local refractive index perceived by the evanescent part of the electromagnetic field of the first portion of the light radiation, and a second waveguide called reference arm wherein a second portion of the light radiation is propagated, an encapsulation layer encapsulating the reference arm, the encapsulation layer being impermeable to the compound or compounds to be detected, so that the reference arm is exposed only to a second ambient medium, substantially of the same nature as the first ambient medium and without the compound to be detected and interferometric sensor comprising a photonic integrated circuit according to the invention.

## Claims

### Claim 1

A photonic integrated circuit (PIC) for interferometric sensor comprising:
a bottom layer called substrate;
a first coupling means suitable for coupling an incident light radiation (Lin) to the photonic integrated circuit (PIC);
a directional splitter linked to the first coupling means and configured to split the light radiation (Lin) coupled by the first coupling means to at least one pair of waveguides included in the photonic integrated circuit, each pair of waveguides comprising:
a first waveguide called sensitive arm wherein a first portion of the light radiation is propagated, said sensitive arm being exposed to a first ambient medium (M1) and to at least one compound to be detected (C) inducing a modification of the local refractive index perceived by the evanescent part of the electromagnetic field of the first portion of the light radiation, and
a second waveguide called reference arm wherein a second portion of the light radiation is propagated,
an encapsulation layer encapsulating the reference arm, said encapsulation layer being impermeable to the compound or compounds to be detected (C), so that the reference arm is exposed only to a second ambient medium (M2), substantially of the same nature as the first ambient medium (M1) and without said compound to be detected,
a directional combiner combining the first portion of the light radiation from said reference arm, called first transmitted portion, and the second portion of the light radiation from said sensitive arm, called second transmitted portion, to form a transmitted radiation;
a second coupling means suitable for coupling said transmitted radiation to a medium external to the photonic integrated circuit (PIC);
a top layer called superstrate covering at least the first and the second coupling means, the directional splitter and the directional combiner and not covering the sensitive arm and the reference arm, said encapsulation layer being deposited on top of the superstrate.

### Claim 2 (depends on 1)

The photonic integrated circuit according to claim 1, wherein the sensitive arm and reference arm are spiral-form waveguides.

### Claim 3 (depends on 1)

The photonic integrated circuit according to claim 1, comprising a so-called functionalization layer at least partially covering the sensitive arm and suitable for adsorbing one of the compounds to be detected.

### Claim 4 (depends on 3)

The photonic integrated circuit according to claim 3, comprising a so-called compensation layer at least partially covering the reference arm, a thickness of the compensation layer being equal to or greater than that of the functionalization layer before adsorption of said compound to be detected.

### Claim 5 (depends on 1)

The photonic integrated circuit according to claim 1, wherein the encapsulation layer is porous to the first ambient medium so as to allow a regulation of the relative humidity or of the osmotic pressure of the second ambient medium (M2) relative to the first ambient medium (M1).

### Claim 6 (depends on 1)

The photonic integrated circuit according to claim 1, wherein the encapsulation layer is made of glass, or silicon, polymer or metal.

### Claim 7 (depends on 1)

The photonic integrated circuit according to claim 1, wherein the encapsulation layer is a deformable membrane.

### Claim 8 (depends on 1)

The photonic integrated circuit according to claim 1, wherein an assembly formed by said directional splitter, said reference arm, said encapsulation layer, said sensitive arm and said directional combiner is called interferometric assembly, said photonic integrated circuit comprising a plurality of said interferometric assemblies, at least one additional directional splitter configured to split the light radiation coupled by the first coupling means to a plurality of interferometric assemblies, and a plurality of second coupling means, each suitable for coupling the radiation transmitted by a different interferometric assembly to a medium external to the photonic integrated circuit (PIC).

### Claim 9 (depends on 8)

The photonic integrated circuit according to claim 8, wherein the sensitive arm of each interferometric assembly comprises a so-called functionalization layer at least partially covering the sensitive arm and suitable for adsorbing one of the components to be detected, each functionalization layer being suitable for adsorbing a compound to be detected different from those adsorbed by the other functionalization layers covering the sensitive arm of the other interferometric assemblies.

### Claim 10 (depends on 8)

The photonic integrated circuit according to claim 8, wherein the reference arm of each interferometric assembly is individually encapsulated.

### Claim 11 (depends on 10)

The photonic integrated circuit according to claim 10, wherein the thickness of the individual encapsulation layer is less than 500 microns.

### Claim 12 (depends on 8)

The photonic integrated circuit according to claim 8, wherein the reference arms of the interferometric assemblies are collectively encapsulated, so as to form an encapsulation layer that is uniform and without discontinuity.

### Claim 13 (depends on 12)

The photonic integrated circuit according to claim 12, wherein the thickness of the uniform encapsulation layer is between 5 and 2000 microns.

### Claim 14 (depends on 1)

An interferometric sensor comprising:
a laser source configured to emit an incident light radiation (Lin);
a photonic integrated circuit according to claim 1;
an optical detection system suitable for detecting a light radiation (Lout) from the second coupling means and generating a signal (S) representative of the trend over time of the detected light intensity;
a processing unit for processing said signal, suitable for determining, from the detected intensity, the trend over time of the phase-shift between the first transmitted portion and the second transmitted portion.