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Optical waveguide and method of manufacture

a technology of optical waveguides and manufacturing methods, applied in the field of optical waveguides, can solve the problems of limiting the application of optical signal processing, the characteristics of waveguide materials used are limited, and the current waveguide materials are limited to siosub>2/sub>, semiconductors, and a small range of nonlinear crystals. the effect of heat, electric field, magnetic field or sound modification of optical properties

Inactive Publication Date: 2006-01-26
NIPPON TELEGRAPH & TELEPHONE CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical waveguide and a method of manufacturing it that can overcome the problems of conventional devices. The optical waveguide has a variety of characteristics that can be achieved, including a high refractive index and a low refractive index, making it easy to form. The invention also provides a diffused waveguide that can be formed by diffusing a crystal with a high refractive index material. The optical waveguide is formed from an optical functional material that has a large electrooptical effect and a high acoustooptic effect. The invention takes advantage of the fact that the waveguide material has a Curie temperature that can be controlled by an external electric field. The invention also provides a method of manufacturing the optical waveguide that involves depositing a thin film of the material over a substrate and growing it into a desired configuration. Overall, the invention provides an optical waveguide with improved characteristics that can be easily integrated into optical circuits.

Problems solved by technology

However, since the waveguide materials currently available are limited to SiO2, polymers, semiconductors and a small range of nonlinear crystals, the changing of the optical properties as realized by the method described above is greatly restricted by the characteristic of the waveguide material used, thus imposing limitations on the applicable optical signal processing.
The currently used waveguide materials, however, are limited to SiO2, polymers, semiconductors and a small range of nonlinear crystals.
Hence, the modification of optical properties as realized by the aforementioned application of heat, electric fields, magnetic fields or sound is greatly restricted by the characteristics of the waveguide material used.
The conventional optical ICs therefore have a problem that the applicable range of optical signal processing is very narrow.
Therefore, even in using the novel waveguide material KTaxNb1-xO3, the conventional technology has a problem that the waveguide fabrication process is complex.
Another problem is that, although the waveguide fabrication is essential in obtaining a desired performance, a technique to form waveguides in a KTN crystal has not yet been established.
As to K and Li compounds, there is not much information available about the materials which provide sufficient vapor pressures.
In the case of K in particular, no material has been known which is effective for use with the CVD method.
The essential reason for this is that alkali metal elements such as K and Li tend to be ionized easily and cannot easily be kept in a molecular state necessary for vaporization.

Method used

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  • Optical waveguide and method of manufacture
  • Optical waveguide and method of manufacture

Examples

Experimental program
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embodiment 1

[0065]FIG. 1 is a perspective view showing the fabrication of an optical waveguide applying the present invention. A basic fabrication shown here as an example waveguide structure for explanation uses a ridge type optical waveguide as an optical waveguide and an electric field application from an electrode as an external field application mechanism. In the figure, reference number 1 represents a substrate that functions as an undercladding layer, 2 a waveguide layer having a refractive index higher than that of the substrate 1 and formed from a film of an optical functional material KTaxNb1-xO3 (03 an input optical signal, 4 an electrode, 5 an output optical signal, and 6 an overcladding layer (cover layer) covering the waveguide layer and having a refractive index lower than that of the waveguide layer KTaxNb1-xO3 film 2.

[0066] The input optical signal 3 is transmitted into the KTaxNb1-xO3 film 2. The KTaxNb1-xO3 film 2 changes its optical property by an external voltage signal ap...

embodiment 1-1

[0069] First, the manufacturing process 1 will be explained. In this embodiment, the liquid phase epitaxy capable of forming a single crystal film with high quality was adopted as the method of depositing a high quality KTaxNb1-xO3 film on the substrate 1. A KTaxNb1-xO3 (0≦x≦1) substrate, a MgO substrate, a MgAl2O4 substrate and a NdGaO3 substrate were used for the substrate 1. As the buffer layer (undercladding layer) were used a semiconductor Si substrate, a GaAs substrate and an InP substrate, which were formed by depositing such materials as SiO2, KTaxNb1-xO3 (0≦x≦1), MgO, MgAl2O4 and NdGaO3.

[0070] To prevent a possible contamination, the KTaxNb1-xO3 film 2 was formed by using potassium oxide and KTaxNb1-xO3 oxide as a solvent and a solute, respectively, and by using a self-flux method. As the potassium oxide solvent, a mixture of KVO3 and K2O (KVO3=30-70 mol %) or K2CO3 carbonate was used. When a KTayNb1-yO3 (0≦y≦1) substrate was used, a material with x (01 are shown to have c...

embodiment 1-2

[0074] Next, the manufacturing process 2 will be explained. Photolithography was used to process the KTaxNb1-xO3 film to form a waveguide layer of a ridge type optical waveguide. A resist was applied to the thin film thus formed and was exposed and developed by using a mask for a 2 μm wide waveguide. The material was then etched by an ion milling method and the residual resist was removed, thereby forming a waveguide layer of the ridge type waveguide. The waveguide layer is nearly a 2 μm square and an observation of the side wall using a SEM (scanning electron microscope) found no significantly roughened surface.

[0075] The measurement of loss of this ridge type waveguide at a wavelength of 1.55 μm showed a loss value of 0.99 dB / cm, which means that the waveguide layer formed is good enough so that undulations of the surface as a result of processing can be neglected.

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Abstract

An optical waveguide capable of having various characteristics and a method of manufacture thereof as well as a method of manufacturing a crystal film are provided. An optical functional material KTaxNb1-xO3 is used as an optical waveguide. The input optical signal is transmitted to the KTaxNb1-xO3 film. The KTaxNb1-xO3 film undergoes changes in optical property when an external voltage signal-is applied to the electrode. Therefore, as it passes through the KTaxNb1-xO3 film, the input optical signal is modulated by the characteristic change. The modulated optical signal is taken out as an output optical signal.

Description

[0001] This application is based on Japanese Patent Application Nos. 2001-143570 filed May 14, 2001, 2001-143571 filed May 14, 2001, 2001-146560 filed May 16, 2001 and 2001-165283 filed May 31, 2001, the contents of which are incorporated hereinto by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an optical waveguide and a method of manufacture thereof and more particularly to an optical waveguide for novel functional optical integrated circuits using an optical functional material KTaxNb1-xO3 as the optical waveguide and a method of manufacture thereof and also to a method of manufacturing a crystal film for use with optical communication devices. [0004] 2. Description of the Related Art [0005] Intensive research and development efforts are being made from a cost performance point of view to develop optical integrated circuits that integrate on a single substrate optical devices that perform emission, detection, modul...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B6/10G02B6/12G02B6/132G02F1/00G02F1/035G02F1/355
CPCG02F1/3551Y10T29/49016G02B6/132G02B2006/12035G02B2006/12097G02B2006/121G02B2006/12109G02B2006/12142G02B2006/12164G02B2006/12173G02B2006/12176G02B2006/12178G02B2006/1218G02F1/0027G02F1/035Y10S117/918G02B6/13
Inventor SASAURA, MASAHIROFUJIURA, KAZUOENBUTSU, KOJIIMAI, TADAYUKIYAGI, SHOGOKURIHARA, TAKASHIABE, MAKOTOTOYODA, SEIJIKUBOTA, EISHI
Owner NIPPON TELEGRAPH & TELEPHONE CORP
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