# US 8,542,433 B2 · Electromagnetic wave oscillating devices and a method of producing the same

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- Number: US 8,542,433 B2
- Document ID: US8542433B2
- Status: Granted
- Kind: B2
- Application number: 13/718,511
- Filed: 2012-12-18
- Published: 2013-06-20
- Granted: 2013-09-24
- Earliest claimed: 2011-12-20
- Assignees: NGK Insulators, Ltd.
- Applicants: NGK Insulators, Ltd.
- Inventors: Jungo Kondo; Yuichi Iwata; Tetsuya Ejiri
- Web page: https://patentgrep.com/patent/US8542433B2

## CPC

- H01S 5/0604: {comprising a non-linear region, e.g. generating harmonics of the laser frequency}
- G02F 1/3534: {Three-wave interaction, e.g. sum-difference frequency generation (G02F1/3532 takes precedence)}
- G02F 2201/30: grating
- G02F 2201/38: Anti-reflection arrangements
- G02F 2203/13: involving THZ radiation
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- 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

It is provided a device oscillating an electromagnetic wave having a target frequency of 0.1 THz to 30 THz. The device includes a main body made of a non-linear optical crystal and a sub-wavelength grating structure formed on the main body. The sub-wavelength grating structure includes protrusions arranged in first direction “X” and second direction “Y” on the main body, first grooves 3X each provided between the adjacent protrusions and extending in the first direction, and second grooves 3Y each provided between the adjacent protrusions and extending in the second direction. Each of the protrusions includes a pair of first faces opposing in the first direction “X” with each other and a pair of second faces opposing in the second direction “Y” with each other. The width of the first face is made smaller from the main body 7 toward an upper end 2c of the protrusion 2.

## Claims

### Claim 1

A device comprising a non-linear optical crystal, said device oscillating an electromagnetic wave having a target frequency of 0.1 THz to 30 THz from said crystal to outside of said crystal:
said device comprising a main body comprising said non-linear optical crystal and a sub-wavelength grating structure formed on said main body;
wherein said sub-wavelength grating structure comprises protrusions periodically arranged in first and second directions on said main body, respectively, first grooves each provided between said adjacent protrusions and extending in said first direction, and second grooves each provided between said adjacent protrusions and extending in said second direction,
wherein each of said protrusions comprises an upper end, a pair of first faces opposing in said first direction with each other, and a pair of second faces opposing in said second direction with each other,
wherein a width of said first face is made smaller from said main body toward said upper end of said protrusion, a width of said second face is made smaller from said main body toward said upper end of said protrusion, said first groove forms a curved profile in a cross section cut along a direction of width of said first groove, and said second groove forms a curved profile in a cross section cut along a direction of width of said second groove.

### Claim 2 (depends on 1)

The device of claim 1, wherein said first faces and said second faces of each of said protrusions are flat.

### Claim 3 (depends on 1)

The device of claim 1, wherein said first faces and said second faces of each of said protrusions are concave faces.

### Claim 4 (depends on 1)

The device of claim 1, wherein said first and second directions are intersected at a right angle.

### Claim 5 (depends on 4)

The device of claim 4, wherein each of said protrusions is of a pyramidal shape.

### Claim 6 (depends on 1)

The device of claim 1, wherein said upper end of each of said protrusions is flat.