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Browse Prior Art Database

Potassium Titanyl Phosphate Ridge Waveguide Frequency Doubler with Tight Mode Confinement

IP.com Disclosure Number: IPCOM000113188D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Kurdi, B: AUTHOR [+2]

Abstract

Waveguide second-harmonic generation provides a method for efficient generation of blue light from GaAlAs diode laser sources. Tight confinement of the infrared and blue radiation over a long interaction length is the key feature leading to high SHG conversion efficiencies. Waveguides for this purpose can be fabricated in KTP (potassium titanyl phosphate) using an ion-exchange process, where rubidium ions replace potassium in a layer a few microns thick near the surface of the crystal.

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Potassium Titanyl Phosphate Ridge Waveguide Frequency Doubler with
Tight Mode Confinement

      Waveguide second-harmonic generation provides a method for
efficient generation of blue light from GaAlAs diode laser sources.
Tight confinement of the infrared and blue radiation over a long
interaction length is the key feature leading to high SHG conversion
efficiencies.  Waveguides for this purpose can be fabricated in KTP
(potassium titanyl phosphate) using an ion-exchange process, where
rubidium ions replace potassium in a layer a few microns thick near
the surface of the crystal.

      Typically, such devices are fabricated using "Z-cut" KTP
substrates, since ion exchange is highly anisotropic in this
material, taking place primarily along the Z-axis, with very little
lateral diffusion along the X- and Y-directions (Fig. 1(a)).  Such
guides are typically 4 microns wide and several microns deep.  The
index step between the ion-exchanged region and surrounding substrate
varies with depth and is at most &tilde.  0.025.

      Tighter confinement can be obtained using an alternative
geometry that is the subject of this invention.  In this geometry, an
X-cut substrate is used, and a ridge perhaps 1 micron wide and 0.6
micron tall is formed by ion milling of the surrounding area.  The
refractive index in this ridge is then increased by ion exchange in
molten RbNO&sub3.  or mixed RbNO&sub3./Ba(NO&sub3.)&sub2..  Since
there is no appreciable diffusion in the X-direction, only the area
of the ridge is affected by the ion exchange, and since the width of
the rid...