JPS62269907A - Integrated optical waveguide - Google Patents

Abstract

PURPOSE:To integrate plural laser light sources about their pitches, angles and modes with high density and high accuracy by setting up the waveguide pitches of the incident side of monolithically integrated optical waveguides smaller than that of the outgoing side. CONSTITUTION:The waveguide pitches of the incident side of the monolithically integrated optical waveguides 105a-105c are set up smaller than that of the outgoing side and the outgoing directions of plural beams on the outgoing side are made different each other. For instance, a SiO2 layer with about 2mum thickness is formed on a silicon substrate by sputtering to obtain a buffer layer for an optical waveguide layer, coning #7059 is sputtering by 1mum to form the optical waveguide layer 110, and after forming a buffer layer 111 with 0.5mum thickness, the waveguide with 2mum width is formed by dry etching. Then, the whole layers are covered with a SiO2 sputtering film with 1mum thickness to form the waveguides. Angles formed by the waveguides 105a-105c and a face 106 are made different each other to project incident beams respectively in oblique directions.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Technical Summary) The present invention relates to an integrated optical waveguide in which a plurality of leading waveguides are monolithically formed.

[Prior art]

Conventionally, when designing an optical scanning device using a plurality of semiconductor lasers or light emitting diodes (LEDs), as disclosed in JP-A-59-126, for example, the light emitted from the light emitting body is The light sources are arranged so that the emission directions of the two intersect at one point P0, so that a plurality of scanning spots can be scanned on a surface to be scanned (not shown) while maintaining a good image formation state.

FIG. 6 shows a typical conventional example, and is a diagram of the optical system between the light source and the deflector, viewed from a direction perpendicular to the deflection scanning plane. 71a and 71b are semiconductor lasers, and each laser is arranged on the mount 72 so that its light beam generating surface is parallel to the end surface of the mount 72. Semiconductor laser 71a.

End surfaces 72a, 7 of the mount 72 where the mount 71b is provided
2b is as if the central rays ha and hb of the diverging light beams from each laser 71a and 71b had passed through the same point P0 (
Set. In other words, semiconductor lasers (71a, 7t
The end surfaces 72a and 72b are set such that when normal lines are drawn to each of the end surfaces 72a and 72b at the position where point h) is provided, each normal line passes through PO. Furthermore, the mount 72 is arranged so that, when viewed from a direction parallel to the deflection scanning plane, the position where the center beams ha and hb of each semiconductor laser pass through the PO point is slightly displaced in a direction perpendicular to the deflection scanning plane.
The position of the semiconductor laser provided above is set. A point P in the predetermined vicinity of the above 20 points and the deflection reflecting surface 78 of one deflector
are maintained in an optically congruent relationship by the imaging lens 74.

In this way, in order to arrange multiple semiconductor light emitters (for example, semiconductor lasers) so that their respective light emission directions are different, they must be aligned on the mount and configured into a hybrid structure, as shown in the example above. I needed to. For convenience, the term "array laser" will be used below to refer to a plurality of semiconductor light emitters, but in principle it also applies to light emitters such as LED arrays.

Furthermore, when using a monolithically formed array laser, it is necessary to install some kind of optical system in front of the array laser. In an example disclosed in Japanese Patent Laid-Open No. 58-211735, a prism is placed in front of an array laser. This is shown in FIG.

FIG. 7 shows a cross section of a prism when a semiconductor array laser has five light emitting parts.

81 is five light emitting parts (81a, 81b, 81c).

81d, 81e),
82 is a prism. The central ray ha of the luminous flux from the light emitting part 81a is refracted by the inclined surface 82a, and the light beam ha is as if P. It is bent as if it had passed through. Similarly, the central ray hb from 81b is bent by the inclined surface 82b, the central ray hd from 81d is bent by the inclined surface 82d, and the central ray he from 81e is bent by the inclined surface 82e, as if they had passed through Po. . Note that the central ray ha from 81c passes through the plane 82c perpendicularly, and Po exists on an extension of this central ray he. In this way, an inclined plane with a defined inclination angle is provided corresponding to each light emitting section, and the center ray of each luminous flux after exiting the prism 82 is as if P. Its direction is controlled as if it were emitted from a source. As described above, this Po is kept conjugate with a desired position P (not shown) near the deflection/reflection surface via the optical system.

Problems in this case include the precision and method of microfabrication of the prism 82, the alignment and bonding method between the prism 82 and the array laser 81, and the smaller the pitch of the array laser, the more difficult it becomes. In fact, it is almost impossible if the thickness is less than 100 μm.

On the other hand, FIG. 8 shows an attempt to achieve the same effect with an optical system, that is, a relay optical system 93, with array lasers 91a, 9
This is an example in which a relay system 93 is interposed between a collimator lens 92 and a cylindrical lens 95 that collimate and image the light emitted from 1b, and an image is formed on a polygon surface 94. (not shown).

The problem in this case is the optical path length, and the relay system itself is approximately 2
It becomes 0cm longer.

[Summary of the invention]

An object of the present invention is to solve the problem (large bulkiness) when using a relay optical system by using it together with a semiconductor array laser and making the emission direction of the plurality of light sources oblique, and to integrate the semiconductor array laser in a high density. An object of the present invention is to provide an integrated optical waveguide that solves problems such as optical output fluctuations due to mutual heat generation that sometimes occur.

In order to achieve the above object, in the present invention, the waveguide pitch on the output side is smaller than the waveguide pitch on the input side with a guide waveguide that is integrally integrated, and the output direction of a plurality of lights on the output side. We propose an integrated optical waveguide designed such that the waveguides are different from each other.

In addition, the expression "each light's emission direction is different" used in the following description does not mean that the lights are emitted in the same direction or that there is no set of lights, but in a broad sense, there is one or more sets of lights that emit light in different directions. It means to do.

〔Example〕

FIG. 1(a) shows a glass waveguide 105 formed on a silicon substrate 104. The manufacturing method is to sputter 5 in 2 on a silicon substrate to form a layer of about 2 μm to form a buffer layer for the leading wave layer, and then use Corning #705.
9 was sputtered to a thickness of 1 μm to form a leading wave layer 110.

Furthermore, after forming a buffer layer I11 with a thickness of 0.5 μm, a waveguide with a width of 2 as shown in FIG.
It was formed in μm. Next, the entire structure was once again covered with a 1 μm thick sputtered film of 5i02 to obtain a cross-sectional view as shown in FIG. Since the 5in2 sputtered film has a refractive index about 0.1 smaller than the #7059 sputtered film, a waveguide is formed.

The waveguides f05a and 105c are drawn with exaggerated spacing, and the pitch of the waveguides on the 120 plane that couples with the laser is 200 μm1, and 50 μm on the exit surface 106.
It was formed to have a pitch of . The interval between the 106 and 120 planes is about 400 μm, and each plane is smoothed by polishing.

In addition, the beams emitted from the 106th surface pass through the waveguides 105a to 105.
The angles that the 5Cs make with respect to the 106 plane are different, and the light beams are emitted in diagonal directions.

The lasers to be coupled are three semiconductor lasers having independently driven electrodes with an oscillation wavelength of 780111 [0] formed on a 101 GaAs substrate.

The laser light propagates in the waveguide 105 in a single mode.

FIG. 1(b) is a schematic view of the surface of the coupling viewed laterally from direction B'.

Light bends at the exit surface approximately according to Snell's law.

Although it is of course possible to form the surface 106 not in one plane but at an angle by dry etching as shown in FIG. 3, it is necessary to form the output end surface 106 smoothly.

FIG. 4(a) shows an example in which optical input to the waveguide is not from an array laser but by using a fiber 201.

That is, in FIG. 4(a), 202 represents the core of the fiber, and the laser beam input to this fiber may be from a separate semiconductor laser, and does not need to be a monolithically formed array laser.

A C-σ cross section is shown in FIG. 4(b).

A groove 203 is formed on a substrate common to the St3 plate on which the waveguide is formed, so that the core of the fiber and the waveguide are coupled at the correct position.

FIG. 5(a) is an example in which the substrate on which the waveguides shown in FIGS. 1(a) to 2 are formed is monolithically formed with a semiconductor laser.

FIG. 5(b) is a top view of the same structure.

That is, a so-called double heterostructure is formed on a GaAs substrate 301 by normal crystal growth, and after a stripe-shaped injection region is formed, injection electrodes 303 and 304 are formed. The cavity surface 305 is dry etched to form the active layer 302.
A semiconductor laser is formed by processing perpendicular to the .

Next, a waveguide using Corning #7059307 as a waveguide was formed by bending in the same process as in FIG.

The active layer and the core 307 are made to have almost the same height to facilitate coupling, and in FIG. 3(b), mask alignment is performed using photolithography to reduce lateral deviation with the laser injection area. ing.

In addition to the above waveguides, TtO2 (cladding) and 5i
Combinations such as 02 (core) can be selected appropriately.

GaAsAflGaA, the same material as semiconductor laser light sources
Even a waveguide using s is sufficiently effective because it can be used for propagation of several 100 μm and several mm.

These multiple waveguides do not necessarily need to emit laser light obliquely at the time of emission, and are generally effective in reducing the pitch of the array light source at the output end face compared to the input end face. It goes without saying that the light source to be used is not limited to only semiconductor lasers, and light sources guided by fibers (eg, gas lasers) are also effective.

〔Effect of the invention〕

In the monolithically integrated leading waveguide of the present invention, the integrated optical waveguide is designed such that the waveguide pitch on the output side is smaller than the waveguide pitch on the input side, and the directions of output of a plurality of lights on the output side are different from each other. , it has become possible to integrate multiple laser light sources with high density and precision (pitch, angle, mode).

In addition, there is almost no thermal interference between the light sources, making it possible to obtain stable output.

This is extremely effective as a light source for an optical device (such as a laser beam printer) that forms and scans an image on a medium using a scanning optical system, and it has become possible to obtain good recording characteristics.

[Brief explanation of the drawing]

FIG. 1(a), FIG. 1(b), FIG. 2, and FIG. 3 are views showing one embodiment of the present invention, and FIG. 4(a), FIG.
), FIGS. 5(a) and 5(b) are views showing modified examples of the present invention, FIG. 6 is a view showing a conventional example in which lasers are arranged in a hybrid manner, and FIG. 7 is a view showing a conventional example in which lasers are arranged in a hybrid manner. FIG. 8 is a diagram showing a conventional example in which an array laser and a prism are combined to have different emission directions, and FIG. 8 is a diagram showing a conventional example in which an attempt is made to correct an array laser whose emission direction is constant using an optical system. 101 one board, 105a~105cm optical waveguide first item (
0) Figure 1 (b) Figure 76 Figure '''7

Claims (3)

[Claims] (1) An integrated optical waveguide characterized in that a plurality of waveguides are monolithically formed, and the waveguide pitch on the output side is different from the waveguide pitch on the input side. (2) The integrated optical waveguide according to claim 1, wherein the pitch on the output side is smaller than the pitch on the input side. (3) The integrated optical waveguide according to claim 1, wherein the integrated optical waveguide is formed so that the light exit directions are different.