Device for shaping a laser beam for an atomic sensor having retroreflector prism, linear polarizer, and form birefringence plate

Patent metadata

Field	Value
Publication number	US-11002977-B2
Application number	US-201615748563-A
Country	US
Kind code	B2
Filing date	Jul 21, 2016
Priority date	Jul 28, 2015
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

Device for shaping a laser beam for an atomic sensor, comprising a retroreflector prism with an entrance area, an exit area and two reflection surfaces forming a right angle therebetween. The device for shaping includes a linear polarizer disposed upstream from the entrance area of the retroreflector prism for linearly polarizing a laser beam entering into the retroreflector prism by the entrance area, and a form birefringence plate disposed downstream from the exit area of the retroreflector prism to circularly polarize a laser beam exiting from the retroreflector prism by the exit area.

First claim

The invention claimed is:

1. A laser beam shaping device intended in particular to be included in an atomic sensor such as an atomic clock, atomic magnetometer or atomic gyrometer by being combined both with a laser beam emission laser and also an alkaline vapor cell comprising a cavity filled with a gas into which a shaped laser beam could enter and a photo detector for receiving a laser beam having entered the cell,
the shaping device comprises a retroreflector prism comprising an entrance area for an entering laser beam, an exit area for an exiting laser beam and also two internal laser beam reflection surfaces, said reflection surfaces forming a right, angle therebetween,
wherein the shaping device further comprises
a linear polarizer disposed upstream from the entrance area of the retroreflector prism so as to be traversed by a laser beam entering the retroreflector prism by the entrance area and able to linearly polarize said entering laser beam, and
a form birefringence plate disposed downstream from the exit area of the retroreflector prism so as to be traversed by a laser beam exiting the retroreflector prism by the exit area and able to circularly polarize said exiting laser beam in order to obtain a shaped laser beam.

2. The device according to claim 1 , wherein the linear polarizer comprises a sub-wavelength metal network, and wherein the sub-wavelength metal network of the linear polarizer comprises a plurality of metal plates extending parallel to each other along a metal plate direction and being juxtaposed one relative to the other along a passing direction of the metal network perpendicular to the metal plate direction.

3. The device according to claim 2 , wherein the passing direction of the metal network is parallel to a direction of intersection between the respective geometric planes of extension of the two reflection surfaces.

4. The device according to claim 1 , wherein the form birefringence plate comprises a zero-order sub-wavelength dielectric network, and Wherein the zero-order sub-wavelength dielectric network of the form birefringence plate comprises a plurality of dielectric plates extending parallel to each other along a dielectric plate direction and being juxtaposed one relative to the other along a dielectric network direction perpendicular to the dielectric plate direction.

5. The device according to claim 4 , wherein the linear polarizer comprises a sub-wavelength metal network, wherein the sub-wavelength metal network of the linear polarizer comprises a plurality of metal plates extending parallel to each other along a metal plate direction and being juxtaposed one relative to the other along a passing direction of the metal network perpendicular to the metal plate direction, and wherein, the dielectric plate direction forms an angle of 45° with the metal plate direction.

6. The device according to claim 4 , wherein the passing direction of the metal network is parallel to a direction of intersection between the respective geometric planes of extension of the two reflection surfaces, and wherein the dielectric plate direction forms an angle of 45° with the metal plate direction.

7. The device according to claim 1 , wherein the linear polarizer and the form birefringence plate are disposed side-by-side on a glass plate—or wafer.

8. The device according to claim 1 , wherein the entrance area and the exit area of the retroreflector prism form two portions of the retroreflector prism transmission surface and in which the linear polarizer and the form birefringence plate are placed facing said transmission surface, which are either formed on said transmission surface or formed on a glass plate—or wafer—placed facing said transmission surface.

9. An atomic sensor comprising a device for shaping a laser beam according to claim 1 , combined, compactly, both with a laser beam emission laser and also an alkaline vapor cell comprising a cavity filled with a gas into which a shaped laser beam could enter and a photo detector for receiving a laser beam having entered the cell.

10. The atomic sensor according to claim 9 , wherein a preferred direction of polarization of a laser beam emitted by the emission laser is substantially aligned with the passing direction of the linear polarizer metal network.

11. A process for fabrication of a device for laser beam shaping intended in particular to be included in an atomic sensor such as an atomic clock, atomic magnetometer or atomic gyrometer by being combined both with a laser beam emission laser and also an alkaline vapor cell comprising a cavity filled with a gas into which a shaped laser beam could enter and a photo detector for receiving a laser beam having entered the cell, wherein:
a retroreflector prism is disposed comprising an entrance area for an entering laser beam an exit area for an exiting laser beam and also two internal laser beam reflection surfaces, said reflection surfaces forming a right angle therebetween,
a linear polarizer is formed and disposed able to linearly polarize an entering laser beam and disposed upstream from the entrance area of the retroreflector prism so as to be traversed by a laser beam entering the retroreflector prism by the entrance area; and
a form birefringence plate is formed and disposed able to circularly polarize an exiting laser beam and disposed downstream from the exit area of the retroreflector prism so as to be traversed by laser beam exiting the retroreflector prism by the exit area.

12. Process according to claim 11 , wherein
the linear polarizer is formed by depositing a metal layer on a glass plate—or wafer, in particular an aluminum or gold layer; and
the form birefringence plate is formed on said glass plate—or wafer—either by depositing a layer of dielectric material, in particular a silicon nitride layer, on said glass plate—or wafer—or by etching said glass plate—or wafer;
the linear polarizer is disposed upstream from the entrance area of the retroreflector prism and the form birefringence plate downstream from the exit area of the retroreflector prism by placing the glass plate—or wafer—facing a transmission surface of the retroreflector prism, where the entrance area and the exit area of the retroreflector prism form two portions of said transmission surface.

13. Process according to claim 11 , wherein
the linear polarizer is formed and disposed upstream from the entrance area of the retroreflector prism by depositing a layer of metal material, in particular a layer of aluminum or gold, on a transmission surface of the retroreflector prism, the entrance area of the retroreflector prism forming a portion of said transmission surface; and
the form birefringence plate is formed and deposited downstream from the exit area of the retroreflector prism either by depositing a layer of dielectric material, in particular a layer of silicon nitride, on the transmission surface of the retroreflector prism, the exit area of the retroreflector prism forming a portion of said transmission surface, or by etching of said transmission surface.

Assignees

• Centre National De La Rech Scientifique—Cnrs
• Univ Franche Comte

Inventors

• Passilly Nicolas
• Gorecki Christophe
• Maurice Vincent

Classifications

• G02B27/0972 Primary

  Prisms (prisms per se G02B5/04) · CPC title

• G02B5/04

  Prisms · CPC title

• G02B5/122

  cube corner, trihedral or triple reflector type · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G02B5/3058

  comprising electrically conductive elements, e.g. wire grids, conductive particles · CPC title