# US 8,999,181 B2 · Method for manufacturing ridge-type waveguide

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- Number: US 8,999,181 B2
- Document ID: US8999181B2
- Status: Granted
- Kind: B2
- Application number: 13/905,157
- Filed: 2013-05-30
- Published: 2014-06-19
- Granted: 2015-04-07
- Earliest claimed: 2012-12-14
- Assignees: Hon Hai Precision Industry Co., Ltd.
- Applicants: Hon Hai Precision Industry Co., Ltd.
- Inventors: Hsin-Shun Huang
- Web page: https://patentgrep.com/patent/US8999181B2

## CPC

- G02B 6/10: of the optical waveguide type (G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00)
- G02B 6/136: by etching
- G02B 2006/12097: {Ridge, rib or the like}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

In a method for manufacturing a ridge-type waveguide, a substrate is provided. An etching resistance stripe is coated on the substrate. The substrate with the etching resistance stripe is subjected to a wet etching process to form a ridge under the etching resistance stripe. The etching resistance stripe is removed. A titanium stripe is then coated onto the ridge and diffused into the ridge to form a waveguide in the ridge by a high temperature diffusing process.

## Claims

### Claim 1

A method for manufacturing a ridge-type waveguide, the method comprising:
providing a substrate made of lithium niobate crystal;
coating an etching resistance stripe on the substrate;
dipping the substrate with the etching resistance stripe into a first etchant to form a ridge under the etching resistance stripe using a first wet etching process;
removing the etching resistance stripe;
coating a titanium stripe on the ridge; and
diffusing the titanium stripe into the ridge to form a waveguide in the ridge by a thermal diffusing process at a selected temperature.

### Claim 2 (depends on 1)

The method of claim 1, wherein the substrate is substantially rectangular and comprises a rectangular top surface, the etching resistance stripe extends along a length direction of the substrate and is positioned generally at a central part of a width direction of the top surface.

### Claim 3 (depends on 1)

The method of claim 1, wherein the etching resistance stripe is made of chromium.

### Claim 4 (depends on 1)

The method of claim 1, wherein the step of coating the etching resistance stripe comprises:
coating an etching resistance layer on the top surface; and
performing a photolithography process to the etching resistance layer to produce the etching resistance stripe.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first etchant is hydrofluoric acid.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first wet etching process lasts about 4 hours and an etching depth into the top surface is about 2-3 microns.

### Claim 7 (depends on 1)

The method of claim 1, wherein the step of removing the etching resistance stripe comprises:
dipping the ridge with the etching resistance stripe into a second etchant to remove the etching resistance stripe using a second wet etching process.

### Claim 8 (depends on 7)

The method of claim 7, wherein the second etchant contains nitric acid.

### Claim 9 (depends on 7)

The method of claim 7, wherein the second wet etching process lasts about 10-20 minutes.

### Claim 10 (depends on 1)

The method of claim 1, wherein the ridge comprises a rectangular upper surface, the titanium stripe extends along a length direction of the ridge and is positioned generally at a central part of a width direction of the upper surface.

### Claim 11 (depends on 1)

The method of claim 1, wherein the step of coating the titanium stripe comprises:
coating a titanium layer on the ridge; and
performing a photolithography process to the titanium layer to produce the titanium stripe.

### Claim 12 (depends on 1)

The method of claim 1, wherein the selected temperature of the thermal diffusing process is about 1020 degrees Celsius.

### Claim 13 (depends on 1)

The method of claim 1, wherein the thermal diffusing process lasts about 10-20 minutes.