JPS6234125A - Optical waveguide type device - Google Patents

Abstract

PURPOSE:To connect both waveguides with each other and to facilitate the manufacture of a device which has good light convergence efficiency by forming the 1st optical waveguide at a specific part of a substrate made of an optical material having optical function effect and forming the 2nd glass optical waveguide at another part of the same substrate across a buffer layer. CONSTITUTION:The 1st optical waveguide 2 is formed on the center part of the substrate 1 which has piezoelectric effect and SiO2 which has a specific refractive index is sputtered at both sides of the substrate 1 where the waveguide 2 is not formed to form the buffer layer 6. Further, coning with a specific refractive index is sputtered on the buffer layer 6 to form the 2nd glass optical waveguide 7. An inter-digital transducer LDT which generates a surface acoustic wave SAW and a light absorbing member 10 are provided on the waveguide 2. Lenses 8 and 9 are provided to the waveguides 7 respectively and both waveguides 2 and 7 are coupled to tapered film thickness. Light from a light source 4 is collimated by the lens 8 and diffracted light or undiffracted light passed through the waveguide 2 is converted by the lens 9 and made incident on a photodetector array 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention A first optical waveguide is formed on a predetermined portion of a substrate made of an optical material having an optical functional effect, and a second optical waveguide is formed on another portion of the same substrate via a buffer layer. glass optical waveguides are formed, both optical waveguides are connected to each other, and an optical functional element is formed in the first optical waveguide, and a lens is formed in the second glass optical waveguide. Optical waveguide device.

BACKGROUND OF THE INVENTION The present invention relates to optical waveguide devices for optical integrated circuits.

An optical integrated circuit confines light in an optical waveguide on a substrate, controls the light using various effects, and processes optical signals. Optical spectrum and spectra as specific optical devices
These include analyzers, optical convolvers, optical Bragg shifters, and optical Fourier transformers. These optical integrated circuits collimate light.

It is always equipped with a lens used for convergence and other purposes.

5 and 6 show an optical spectrum analyzer as an example of an optical integrated circuit.

A two-dimensional optical waveguide (leading wave layer) 32 is formed by thermally diffusing Ti on the L iN b 03 substrate 31 .

Two geodesic lenses 38 are placed on this optical waveguide 32.
, 39 are arranged. Light (indicated by a chain line) entering the optical waveguide 32 from a light source 34 such as a semiconductor laser is frimated by a lens 38 and focused by a lens 39 . A photodetector array (image sensor) 35 is arranged on the focal plane of the lens 39.

Light collimated by the lens 38 and surface acoustic waves (SAW) propagating in a direction that satisfies the conditions of Bragg diffraction.
An interdigital transducer (I
DT) 33 is arranged on the optical waveguide 32. The radio frequency (RP) signal whose spectrum is to be analyzed is the IDT
33, a corresponding SAW is generated and interacts with the light. The diffraction angle of light diffracted by the SAW (an example of which is shown by a broken line) is approximately proportional to the RP multiplied signal frequency, and the single diffraction efficiency is approximately proportional to the RF power in the small signal region. Therefore, from the detector array 35, RF
A spectral signal representing the doubled signal frequency and power is obtained.

Geodesic lenses and Luneburg ◆ lenses are often used in such optical waveguide devices, but these lenses require cutting and dome formation, making them difficult to manufacture. The yield is not good and the manufacturing accuracy is not high either.

Another problem is that the lens becomes larger.

Although other waveguide lenses, such as Fresnel lenses and grating lenses, can be made smaller, Ti-diffused L
Since it is not possible to obtain a large refractive index change in the iNbO3 optical waveguide, the light collection efficiency is low and the numerical aperture NA is also small.

[Object of the invention] This invention is small, easy to manufacture, and highly accurate in manufacturing.
It is an object of the present invention to provide an optical waveguide device that can produce a lens with high light collection efficiency and large NA.

[Structure and Effects of the Invention] In the guided wave type device according to the present invention, a first optical waveguide is formed on a predetermined part of a substrate made of an optical material having an optical function effect, and a buffer is formed on another part of the same substrate. A second glass optical waveguide is formed through the layer, and these image optical waveguides are connected to each other.

A feature is that an optical functional element is formed in the first optical waveguide, and a lens is formed in the second glass optical waveguide.

Here, the optical functional effect refers to a phenomenon in which the properties of a material, especially the properties for realizing an optical functional element, change when some physical quantity is applied from the outside, such as piezoelectric effect, f @ magneto-optic effect, magneto-optic effect, etc. say. Furthermore, optical waveguides include not only three-dimensional optical waveguides.

The concept includes a two-dimensional optical waveguide, a so-called leading wave layer.

Since the first optical waveguide is formed on an optical material having an optical function effect, various optical function elements can be formed there, so that desired optical control can be realized. The lenses necessary for this optical integrated circuit can be fabricated on the second glass optical waveguide. Since lenses can be fabricated on glass optical waveguides, large refractive index changes can be obtained, making Fresnel
It is possible to create lenses, gratings, and lenses.

The lens is miniaturized, 7 it is easy to manufacture, 1 the manufacturing accuracy is good, 2 the yield is good, the light collection efficiency is high, and the NA can be increased.

[Description of the Embodiment] FIGS. 1 and 2 show an embodiment of the invention, in which an optical spectrum analyzer is realized. The substrate 1 is Y-cut L iN b O3 having a piezoelectric effect, and the optical waveguide 2 is formed on the center part of the substrate 1 using titanium (Ti).
200+ was formed by sputtering and a lift-off method, and then thermally diffused in a wet 02 atmosphere at a temperature of 970° C. for 1 hour and 5 hours. Optical waveguide 2 on substrate 1
A buffer layer 6 is loaded by sputtering SiO2 having a refractive index of 1.40 on the parts other than the parts where the optical waveguide 2 was fabricated, that is, on both sides of the optical waveguide 2. Further, a glass optical waveguide 7 is fabricated by sputtering Corning 7059 having a refractive index of 1.53 onto the buffer layer 6. The coupling end of the glass optical waveguide 7 with the optical waveguide 2 is formed into a tapered shape by undercutting the mask during sputtering or by setting the mask slightly in front of the substrate 1 to cause a wrapping effect of the glass. Formed into a thick film. Thereby, the light in the glass optical waveguide 7 is efficiently coupled to the titanium diffused optical waveguide 2. The same is true vice versa.

On the optical waveguide 2 is an IDT 3 that generates a SAW.

A SAW absorption member IO is provided, and the Bragg diffraction effect of light by SAν as described above is performed on this optical waveguide 2.

L iN b O3 has a piezoelectric effect, an acousto-optic effect, an electro-optic effect, and a thermo-optic effect, and is optimal for controlling light waves. An optical functional element is provided in the optical waveguide 2 on this L iN b Oa.

However, the refractive index of L i N b O3 is 2
．． The refractive index of the optical waveguide 2 in which 2°Ti is diffused is 2.20.
4, the difference is 0.004. L iN b O3
When a lens is manufactured by loading some substance on top, the difference in isotropic refractive index of light propagating between the loaded part and the unloaded part is 0.004 or less. Therefore, in order to make the phase difference between the light propagating between the part loaded with a material and the part not loaded with a substance be π in order to function as a lens, a large lens film thickness is required, and the viewing angle becomes small. L iNb
A good lens cannot necessarily be produced on Oa.

Therefore, a glass optical waveguide 7 is provided on the substrate of LIN b Oa, and a lens 8.9 is provided here.

Here, a grating lens is shown as the lens. These lenses 8 and 9 are r S t
Even if a loaded type is formed using O2 sputtering and a lift-off method, a photoresist AZ or a negative type electron beam resist is used as a mask.

A group (groove) type structure may be formed by ion beam etching using C2Fe as a gas. A loading type is shown in FIGS. 1 and 2. The lens 8 is for collimating the light emitted from the light source 4, and the lens 9 is for condensing the diffracted light or undiffracted light that has passed through the optical waveguide 2 onto the photodetector array 5.

Since the refractive index of glass is approximately 1.5 and the refractive index of LiNbOa is 2.2, glass can be directly coated with LiNbO.
Even if it is sputtered onto 3, it will not become an optical waveguide. For this reason, S iO2 with a refractive index of 1.46 is L t N b
A sufficiently thick buffer layer 6 is sputtered on the buffer layer 6, and Corning 7059 having a refractive index of 1.53 is sputtered thereon as the optical waveguide 7. The difference in refractive index between the buffer layer 6 and the optical waveguide 7 is 0.07, and the difference in refractive index between the buffer layer 6 and the optical waveguide 7 is 0.07.
A lens that is 10 times larger than 0.004 in the case of No. 3 and has a small lens thickness can be manufactured. Moreover, the light collection efficiency is also improved.

When manufacturing the above-mentioned loaded type lens,
A SiO3 film patterned by a lift-off method is further loaded onto the optical waveguide 7.

Compared to the equidistant refractive index n of the light propagating in the part not loaded with S iO2, when loaded with S io 2 ef
'['Also, the equidistant refractive index n of light propagating through the part is thick ef'l
'It's going to be 2. The larger the thickness of the loaded film, the larger nerl'2 becomes. The thickness of the lens is λ/ [2(nef'f'
2-nef'f'l), thereby producing the previous phase difference π.

The above-mentioned difference in refractive index of 0.07 and 0.004 is due to the above-mentioned (
neff2 crfl), it is easy to understand that if a lens is fabricated on a glass optical waveguide, the thickness of the lens can be made sufficiently small.

FIG. 3 shows an embodiment in which the present invention is applied to an optical parallel/serial converter. Substrate 1 of L iN b 03
The upper optical waveguide 2 is formed in the center portion and a portion slightly to the left of the substrate 1. Then, from the left optical waveguide 2 toward the left end of the substrate 1, several three-dimensional optical waveguides 12 are the same (formed by thermal diffusion of Ti). A glass optical waveguide 7 is formed through a buffer layer 6, and a lens 8,
9 are provided respectively. An IDT 3 is fabricated on the central optical waveguide 2.

The light incident on the optical waveguide 12 is output to the optical waveguide 2,
Further, they are directed into optical waveguides 7, where they are each collimated by lenses 8. Pulsed SA from IDT 3
ν occurs. First, the first light is Bragg diffracted by this pulsed SAW.

Since SAν is pulsed, other light at this time is SAW
does not interact with The diffracted light is directed from the optical waveguide 2 to the optical waveguide 7, where it is focused by a lens 9. A plurality of lights propagating through the central optical waveguide 2 are successively diffracted by the SAW. In this way, the light incident on the optical waveguide 12 in parallel over time is converted into a serial signal over two hours.

FIG. 4 shows yet another embodiment, which is also an optical parallel/serial converter. here.

This embodiment differs from the embodiment shown in FIG. 3 in that the glass optical waveguide 7 extends toward the left end of the substrate 1 to form a three-dimensional optical waveguide 17.

In the above embodiment, LiN b O3 is used as the substrate material, SiO2 is used as the buffer layer, and Corning 7059 is used as the glass optical waveguide, but it goes without saying that other materials can be used. The method for manufacturing the optical waveguide and the like can also be selected as appropriate depending on the type of material. Furthermore, the lenses are not limited to grating lenses.

The manufacturing method can also be determined depending on the type of lens.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show an embodiment of this invention.
FIG. 1 is a perspective view, and FIG. 2 is a sectional view. FIGS. 3 and 4 are perspective views showing other embodiments of the invention, respectively. 5 and 6 show a conventional example, with FIG. 5 being a perspective view and FIG. 6 being a sectional view. DESCRIPTION OF SYMBOLS 1... Substrate, 2... First optical waveguide, 3... ID
T. 6... Buffer layer, 7... Second glass optical waveguide. 8.9...Lens. Patent applicant: Tateishi Electric Co., Ltd. Agent: Patent attorney: Kenji Ushiku (1 other person) Figure 1 Figure 3 Figure 4 Figure 5 Procedural report voluntarily written on May 2, 1986

Claims (1)

[Claims] A first optical waveguide is formed on a predetermined portion of a substrate made of an optical material having an optical function effect, and a second glass optical waveguide is formed on another portion of the same substrate with a buffer layer interposed therebetween. An optical waveguide device in which optical waveguides are connected to each other, an optical functional element is formed in a first optical waveguide, and a lens is formed in a second glass optical waveguide.