Optical scanning device that includes waveguides

Patent metadata

Field	Value
Publication number	US-11256156-B2
Application number	US-201816108129-A
Country	US
Kind code	B2
Filing date	Aug 22, 2018
Priority date	Sep 29, 2016
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

An optical scanning device includes: a first waveguide that propagates light by total reflection; and a second waveguide. The second waveguide includes: a first multilayer reflective film; a second multilayer reflective film that faces the first multilayer reflective film; and a first optical waveguide layer directly connected to the first waveguide and located between the first and second multilayer reflective films. The first optical waveguide layer has a variable thickness and/or a variable refractive index and propagates the light transmitted through the first waveguide. The first multilayer reflective film has a higher light transmittance than the second multilayer reflective film and allows part of the light propagating through the first optical waveguide layer to be emitted to the outside. By changing the thickness of the first optical waveguide layer and/or its refractive index, the direction of the part of the light emitted from the second waveguide is changed.

First claim

What is claimed is:

1. An optical scanning device comprising:
a first waveguide that propagates light in a waveguide direction by total reflection; and
a second waveguide,
wherein the second waveguide includes:
a first multilayer reflective film;
a second multilayer reflective film that faces the first multilayer reflective film; and
a first optical waveguide layer that is connected directly or through a gap to the first waveguide and located between the first multilayer reflective film and the second multilayer reflective film,

wherein the first optical waveguide layer has a variable thickness and/or a variable refractive index for the light and propagates the light transmitted through the first waveguide,
wherein the first multilayer reflective film has a higher light transmittance than the second multilayer reflective film and allows part of the light propagating through the first optical waveguide layer to be emitted to outside of the second waveguide, and
wherein the thickness and/or the refractive index of the first optical waveguide layer is changed to change the direction of the part of the light emitted from the second waveguide.

2. The optical scanning device according to claim 1 ,
wherein the first optical waveguide layer propagates the light in the same direction as the waveguide direction of the first waveguide.

3. The optical scanning device according to claim 1 ,
wherein a thickness of the first waveguide is unchanged or is changed by an amount different from the amount of change in the thickness of the first optical waveguide layer.

4. The optical scanning device according to claim 1 ,
wherein a refractive index of the first waveguide for the light is unchanged or is changed by an amount different from the amount of change in the refractive index of the first optical waveguide layer for the light.

5. The optical scanning device according to claim 1 , further comprising
an adjusting element that changes the thickness and/or the refractive index of the first optical waveguide layer to change the direction of the part of the light emitted from the second waveguide.

6. The optical scanning device according to claim 5 ,
wherein the first optical waveguide layer contains a material whose refractive index for the light is changed when a voltage is applied, and
wherein the adjusting element changes the refractive index of the first optical waveguide layer by applying a voltage to the first optical waveguide layer to change the direction of the part of the light emitted from the second waveguide.

7. The optical scanning device according to claim 1 ,
wherein |n w1 −n w2 |/n w1 <0.4 holds
where n w1 is a refractive index of the first waveguide for the light, and n w2 is the refractive index of the first optical waveguide layer for the light.

8. The optical scanning device according to claim 1 ,
wherein n w2 and d 2 satisfy 0.95×mλ/(2n w2 )<d 2 <1.5×mλ/(2n w2 ),
where n w2 is the refractive index of the first optical waveguide layer for the light; d2 is the thickness of the first optical waveguide layer; λ is a wavelength of the light in free space; and m is an integer of 1 or more.

9. The optical scanning device according to claim 8 ,
wherein n w2 and d 2 further satisfy
1.2× m λ/(2 n w2 )< d 2 <1.5× m λ/(2 n w2 ).

10. The optical scanning device according to claim 1 ,
wherein n w1 and n w2 satisfy n w1 >n w2 ,
where n w1 is a refractive index of the first waveguide for the light, and n w2 is the refractive index of the first optical waveguide layer for the light.

11. The optical scanning device according to claim 1 ,
wherein part of a surface of the first waveguide has a grating, and the light to be propagated through the first waveguide enters the first waveguide through the grating.

12. The optical scanning device according to claim 1 ,
wherein the light to be propagated through the first waveguide enters the first waveguide through an end surface of the first waveguide.

13. A photodetection system comprising:
the optical scanning device according to claim 1 ;
a photodetector that detects light emitted from the optical scanning device and reflected from a target; and
a signal processing circuit that generates distance distribution data based on an output from the photodetector.

14. The optical scanning device according to claim 1 ,
wherein the first optical waveguide layer has an end surface connected directly to an end surface of the first waveguide.

15. The optical scanning device according to claim 1 , wherein the optical scanning device is configured such that the propagating light in the first waveguide has a reflection angle that is greater than a critical angle of the total reflection.

16. An optical scanning device comprising:
a first waveguide that propagates light in a waveguide direction by total reflection;
a second waveguide; and
a third waveguide,
wherein the second waveguide includes:
a first multilayer reflective film;
a second multilayer reflective film that faces the first multilayer reflective film; and
a first optical waveguide layer that is located between the first multilayer reflective film and the second multilayer reflective film,

wherein the third waveguide includes:
a third multilayer reflective film,
a fourth multilayer reflective film that faces the third multilayer reflective film; and
a second optical waveguide layer that is located between the third multilayer reflective film and the fourth multilayer reflective film,

wherein the second optical waveguide layer is connected directly or through a gap to the first waveguide and propagates the light transmitted through the first waveguide,
wherein the first optical waveguide layer is connected directly to the second optical waveguide layer, has a variable thickness and/or a variable refractive index for the light, and propagates the light transmitted through the second optical waveguide layer,
wherein the first multilayer reflective film has a higher light transmittance than the second multilayer reflective film and allows part of the light propagating through the first optical waveguide layer to be emitted to outside of the second waveguide, and
wherein the thickness and/or the refractive index of the first optical waveguide layer is changed to change the direction of the part of the light emitted from the second waveguide.

17. The optical scanning device according to claim 16 , wherein the optical scanning device is configured such that the propagating light in the first waveguide has a reflection angle that is greater than a critical angle of the total reflection.

18. An optical scanning device comprising a plurality of waveguide units arranged in a first direction,
wherein each of the plurality of waveguide units includes:
a first waveguide that propagates light in a second direction by total reflection; and
a second waveguide,

wherein the second waveguide includes:
a first multilayer reflective film;
a second multilayer reflective film that faces the first multilayer reflective film; and
a first optical waveguide layer that is connected directly or through a gap to the first waveguide and located between the first multilayer reflective film and the second multilayer reflective film,

wherein the first optical waveguide layer has a variable thickness and/or a variable refractive index for the light and propagates the light transmitted through the first waveguide,
wherein the first multilayer reflective film has a higher light transmittance than the second

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Hashiya Akira
• Inada Yasuhisa
• Hirasawa Taku
• Yamaoka Yoshikazu
• Nagao Nobuaki

Classifications

• G02F2201/302

  grating coupler · CPC title

• G02B2006/12104

  Mirror; Reflectors or the like · CPC title

• G02B6/122

  Basic optical elements, e.g. light-guiding paths · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S17/89

  for mapping or imaging · CPC title