JPH04355416A - Waveguide route type optical device - Google Patents

Abstract

PURPOSE:To make dislocation of optical axis hard to be caused. CONSTITUTION:A waveguide route type optical device is constituted of a waveguide route substrate 1, upper splines 2, a support glass 3, a semiconductor laser 5 mounted on a pipe 6 having a flange and a lens 4 to converge outgoing light from the semiconductor laser 5, and the waveguide route substrate 1, the upper splines 2 and the support glass 3 are stuck together, and end face polishing is carried out so as to be on the same plane. On the one hand, the semiconductor laser 5 and the lens 4 are housed after their positions are adjusted beforehand so that the outgoing light from the semiconductor laser 5 can be converged in a flange part of the pipe 6 having the flange through the lens 4. End faces of this waveguide route substrate 1 and the flange surfaces of the pipes 6 having the flange are brought into close contact with each other, and are fixed together after the optical axis is adjusted.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a waveguide type optical device, and more particularly to an optical axis fixing structure for a waveguide type optical device comprising a waveguide and a semiconductor laser optically coupled to the waveguide via a lens. Regarding.

0002

[Prior Art] Generally, a waveguide type optical device forms a region in a ferroelectric substrate or a semiconductor substrate that has a higher refractive index than the periphery that serves as a light waveguide portion (waveguide). An electrode is formed on or near the top, and a voltage is applied to this electrode to utilize the electro-optic effect and other properties of the substrate.
It is an optical device that controls or modulates the phase and intensity of light by changing the refractive index of a waveguide. For example, L, which has a high electro-optic effect as such a waveguide type optical device,
There is an optical device in which a waveguide is formed by patterning and thermally diffusing Ti into a desired waveguide pattern on an iNbO3 substrate, and electrodes are provided to rapidly modulate the intensity of light.

[0003] In the field of optical communications, the current method of directly modulating a semiconductor laser has been changed to a method in which the light oscillated from the semiconductor laser is modulated at high speed using an external intensity modulator in order to achieve higher capacity and higher speed. This is an external modulator that has been widely researched and developed both domestically and internationally.

[0004] When realizing a waveguide-type optical device in which a semiconductor laser and a waveguide are integrated, (a) light from the semiconductor laser is coupled to the waveguide with high efficiency. (b) Reduce the possibility that the light from the semiconductor laser will leak into the substrate other than the waveguide as a stray. (c) Stabilize the optical axis fixing part. That is important.

A first example of a conventional waveguide type optical device having a structure for fixing a semiconductor laser as a light source, a lens for converging light emitted from the semiconductor laser onto a waveguide, and a waveguide substrate is shown in FIG. Shown in 2.

In FIG. 2, the waveguide type optical device of the first example includes a semiconductor laser 5, a lens 4, a waveguide substrate 1, a pedestal 10 for fixing the lens to a metal casing 9, and an LD package. They have a structure in which they are each optically coupled using a fixing pedestal 11 and then fixed independently. For example, the waveguide substrate 1 is fixed to the housing 9 in advance, and the lens 4 is positioned near the end face of the waveguide substrate 1,
The lens 4 is fixed to the housing 9. Finally, the optical axis of the LD package 7 mounted with the semiconductor laser 5 is adjusted, and it is fixed to the housing 9 using a method such as laser welding.

FIG. 3 is a sectional view showing a second example of a conventional waveguide type optical device.

In FIG. 3, the waveguide type optical device of this second example has a structure in which the emitted light from the semiconductor laser 5 is not converged using the lens 4, but is directly coupled to the waveguide. There is. However, in the case of this structure, the distance between the waveguide end face and the emission part of the semiconductor laser is 10 to 50 μm.
Even if the coupling efficiency is close to that level, the coupling efficiency is lower than that of the first example using the above-mentioned lens. Furthermore, the light that has not been coupled to the waveguide enters the waveguide substrate and leaks into the output optical fiber, extremely deteriorating the extinction ratio of the device. For this reason, the first conventional example shown in FIG. 2 is applied.

[0009]

[Problems to be Solved by the Invention] In the conventional waveguide type optical device described above, since the optical axis of both the semiconductor laser and the waveguide is fixed through the housing, when a temperature change occurs, the waveguide There is a problem in that a relative positional shift occurs due to the difference in thermal expansion coefficient between the substrate and the casing, or between the package on which the semiconductor laser is mounted and the casing, which tends to cause an increase in loss due to optical axis misalignment. This tendency is particularly noticeable when the waveguide substrate is large and the fixed area between the substrate and the housing is wide. Also, when force is applied to the housing from the outside, the housing deforms and loss increases due to optical axis misalignment. The problem is that it invites

On the other hand, when coupling the semiconductor laser light to the waveguide, there is a problem in that the workability is poor because the optical axis adjustment work must be performed inside the housing.

[0011]

[Means for Solving the Problems] A waveguide type optical device of the present invention includes a waveguide substrate in which a waveguide is formed, and a semiconductor laser optically coupled to the waveguide through a lens. In the waveguide type optical device, the semiconductor laser and the lens are housed with their positions adjusted in advance so that an image is formed on the flange surface of the flanged pipe, and the flange surface of the flanged pipe and the end surface of the waveguide substrate are in close contact with each other, and the spot of the semiconductor laser imaged on the flange surface of the flanged pipe is adjusted and fixed in advance so that the spot is incident on the waveguide.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a waveguide type optical device according to an embodiment of the present invention.

In FIG. 1, the waveguide type optical device 20 of this embodiment is made of LiNbO3, which has a high electro-optic effect.
100 waveguide patterns formed on a substrate using a Ti film.
A waveguide is formed by thermal diffusion at 0°C for 6 hours, and an electrode is formed on the top of this waveguide via a SiO2 buffer layer.By applying a voltage to the electrode from the outside, the phase of the light can be controlled. Alternatively, it is a phase modulator that can be modulated.

The waveguide type optical device 20 of this embodiment is made by attaching the upper coating 2 to the upper surface of both ends of the waveguide substrate 1 and the holding glass 3 to the lower part thereof with adhesive, and then polishing both end surfaces. A semiconductor laser 5 serving as a light source and an optical fiber 12 are optically coupled to each end face. Here, the optical fiber 12 is housed in the flanged pipe 6, and the end face of the optical fiber 12 is directly applied to the end face of the waveguide substrate 1, and after the optical axis is adjusted in advance, the flange face of the flanged pipe 6 and The end faces of the waveguide substrate 1 are closely attached and fixed to each other. On the other hand, the semiconductor laser 5 is housed in the LD package 7, and its position is adjusted in advance with the flanged pipe 6 in which the lens 4 is housed, and the semiconductor laser 5 is fixed to the contact surface. This unit is fixed by bringing the flange surface of the flanged pipe 6 into close contact with the end surface of the waveguide substrate 1 and adjusting the optical axis.

Note that the end face of the waveguide is polished obliquely to prevent reflected light from returning to the semiconductor laser 5. Finally, the optical unit in which the waveguide substrate 1, the optical fiber 12, and the semiconductor laser 5 are integrated is mounted on the housing 9 by bonding the bottom surface of the holding glass 3.

Next, an example of the experimental results of this example will be explained.

A temperature cycle test was conducted on the present embodiment shown in FIG. 1 and the first conventional waveguide type optical device shown in FIG. When evaluating the optical fiber output, in this example, it was degraded by only 0.5 dB compared to the initial state, whereas in the first conventional example shown in FIG. 2, it was degraded by about 3 dB. Once the LD package 7 of the first conventional example was removed from the housing 9 and the optical axis was readjusted, it returned to its initial state again. For this reason, in this example, the optical axis fixing part is stable,
On the other hand, it can be seen that in the first conventional example, the optical axis fixing part is unstable and the reliability is low.

[0019]

Effects of the Invention As explained above, the present invention does not fix the waveguide substrate, the semiconductor laser, and the lens independently on the housing, but uses a flanged pipe to accommodate the semiconductor laser and the lens. Because it has a structure in which it is directly fixed to the end face of the waveguide substrate, it is not affected by the difference in thermal expansion coefficient between the waveguide substrate and the housing, the expansion and contraction of the adhesive at the fixed part, and the deformation of the housing due to external force. , it has the effect that optical axis deviation is less likely to occur, optically stable, and high reliability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view showing a first example of a conventional waveguide type optical device.

FIG. 3 is a vertical cross-sectional view showing a second example of a conventional waveguide type optical device.

[Explanation of symbols]

1 Waveguide substrate 2 Upper Yatoi 3 Holding glass 4 Lens 5 Semiconductor laser (semiconductor LD) 6 Pipe with flange 7 LD package 8 Semiconductor LD terminal 9 Housing 10 Lens fixing pedestal 11 LD package fixing pedestal 12 Optical fiber 20 Waveguide type optical device

Claims (1)

[Claims] 1. A waveguide type optical device comprising a waveguide substrate in which a waveguide is formed, and a semiconductor laser optically coupled to the waveguide via a lens, wherein the semiconductor laser and the lens are connected to each other. is housed in a position adjusted in advance so that the image is formed on the flange surface of the flanged pipe,
The flange surface of the flanged pipe and the end surface of the waveguide substrate are brought into close contact with each other, and the position is adjusted in advance so that the spot of the semiconductor laser focused on the flange surface of the flanged pipe is incident on the waveguide. A waveguide type optical device characterized in that it is fixed.