JPH05264862A - Optical waveguide module - Google Patents

Abstract

PURPOSE:To suppress the axis mis-alignment of the optical waveguides of a planar optical wave circuit chip and the optical fibers of a fiber arranging means by preventing the nonuniform stagnation of an adhesive in the butt parts between the planar optical wave circuit chip and the fiber arranging means and eliminating the unbalance of the stresses by the thermal shrinkage at the time of curing of the adhesive and the thermal expansion and contraction by an environmental change. CONSTITUTION:Upper substrates 26 for adjusting thickness are provided on the optical waveguides 14 of the planar optical wave circuit chip 16 to diminish the level difference of the butt parts between the planar optical wave circuit chip 16 and the fiber arranging means 24. The butt parts are adhered by the adhesive but the level difference of the butt parts is small and, therefore, the nonuniform stagnation of the adhesive does not arise and the generation of the unbalance of the stresses by the thermal shrinkage at the time of curing of the adhesive and the thermal expansion and contraction by the environmental change is obviated. The axis mis-alignment between the optical waveguides 14 of the planar optical wave circuit chip 16 and the optical fibers 18a of the fiber arranging means 24 is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an optical waveguide module used in optical communication networks and the like.

[0002]

2. Description of the Related Art An optical waveguide module of this type has an optical waveguide 14 formed on a flat substrate 12, as shown in FIG.
A plurality of V-grooves 20a into which the planar lightwave circuit chip 16 having the above and the optical fiber 18a of the optical fiber ribbon 18 connected to the optical waveguide 14 of the lightwave circuit chip 16 are engaged.
And a fiber array tool 24 including a holding cover 22 that abuts the grooved substrate 20 and holds the optical fiber 18a together with the grooved substrate 20.

The planar lightwave circuit chip 16 and the fiber arranging tool 24 are bonded to each other by an adhesive while aligning the optical waveguide 14 and the optical fiber 18a of the fiber arranging tool 24.

[0004]

However, in this optical waveguide module of the prior art, when the adhesive applied to the abutting surface of the lightwave circuit chip 16 and the fiber arranging tool 24 and its periphery is cured, the shrinkage or the like occurs. The butt surfaces are displaced due to the stress generated by the displacement, which tends to cause axial displacement. In particular, as shown in FIG. 3, when there is a step between the end surface 12a of the planar substrate 12 of the planar lightwave circuit chip 16 and the end surface 22a of the holding lid 22 of the fiber arraying tool 24, the adhesive is applied to the portion having this step. Is likely to accumulate, and it is conceivable that axis misalignment may occur due to stress imbalance. Therefore, for example, it is difficult to make a highly accurate connection so that the transmission loss due to the axis deviation can be suppressed to 0.1 dB / place or less. In addition, after the lightwave circuit chip and the fiber arranging device are adhered and fixed to each other, they are easily affected by the thermal expansion of the adhesive, and transmission loss due to axis misalignment increases in a high temperature or low temperature region, and it is possible to cope with environmental changes. It was difficult to obtain a satisfactory optical module.

An object of the present invention is to avoid the above-mentioned drawbacks and to prevent misalignment of the axis due to thermal expansion and contraction of the adhesive due to curing of the adhesive or changes in the environment, and an optical waveguide module having a highly accurate connecting portion. To provide.

[0006]

In order to solve the above problems, the present invention provides a planar lightwave circuit chip having an optical waveguide on a flat substrate and an optical fiber ribbon connected to the optical waveguide of the lightwave circuit chip. A fiber array tool for arranging and holding optical fibers, wherein the planar lightwave circuit chip and the fiber array tool are bonded to each other by aligning the optical waveguide of the planar lightwave circuit chip and the optical fiber of the fiber array tool. In the optical waveguide module, the planar lightwave circuit chip further includes a thickness adjusting upper substrate provided on a flat substrate so as to sandwich the optical waveguide, and the upper substrate is abutted and bonded to the fiber array tool. An object is to provide an optical waveguide module characterized by the above.

[0007]

When the upper substrate for adjusting the thickness is provided on the optical waveguide of the planar lightwave circuit chip as described above, the step difference between the planar lightwave circuit chip and the fiber arranging device becomes small, and therefore, this butting Since the adhesive does not accumulate unevenly in the area, stress imbalance does not occur due to thermal contraction during curing of the adhesive and thermal expansion and contraction due to changes in the environment, and the optical waveguide of the planar lightwave circuit chip and the fiber array It is possible to suppress the axis deviation of the tool from the optical fiber. In addition, the number of butt end faces to be bonded between the planar lightwave circuit chip and the fiber arranging tool is increased, and the bonding strength is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described in detail. FIG. 1 and FIG. 2 show an optical waveguide module 10 according to the present invention. Similarly, a plurality of V grooves 2 into which the planar lightwave circuit chip 16 having the optical waveguide 14 on the flat substrate 12 and the optical fiber 18a of the optical fiber ribbon 18 connected to the optical waveguide 14 of the lightwave circuit chip 16 are inserted.
A grooved substrate 20 having 0a and a lid 2 for abutting against the grooved substrate 20 and sandwiching the optical fiber 18a with the grooved substrate 20.
2 and a fiber array tool 24 including.

The planar lightwave circuit chip 16 and the fiber arranging tool 24 are joined by aligning the optical waveguide 14 and the optical fiber 18a of the fiber arranging tool 24 and adhering the abutting surfaces to each other with an adhesive.

The optical waveguide module 10 of the present invention further comprises thickness adjusting upper substrates 26 provided on the upper surfaces of both ends of the planar substrate 12 so as to sandwich the optical waveguide 14 of the planar lightwave circuit chip 16, and the upper substrate is provided. Reference numeral 26 is abutted against the fiber arranging tool 24 and bonded by an adhesive.

Thus, the planar lightwave circuit chip 16
When the upper substrate 26 for adjusting the thickness is provided on the optical waveguide 14 of the above, the planar lightwave circuit chip 16 and the fiber arrangement tool 24 are provided.
The step at the butting portion with and becomes extremely small or not at all. Therefore, the adhesive is not unevenly accumulated at the abutting portion, and the heat shrinkage at the time of curing the adhesive and the stress imbalance due to the thermal expansion and contraction due to the change of the environment do not occur, and thus the planar lightwave circuit chip 16 It is possible to suppress axial misalignment between the optical waveguide 14 and the optical fiber 18a of the fiber arranging tool 24.

Next, referring to the first embodiment of the present invention,
1m thick as a planar substrate for planar lightwave circuit chips
A 7.62 cm (3 inch) silicon single crystal substrate of m was used, and a lower clad layer and a core layer were sequentially formed on this single crystal substrate by a flame deposition method. Then, the waveguide pattern was transferred onto this substrate by photolithography, and the portion other than the waveguide pattern portion of the core layer was removed by dry etching. Next, the upper clad layer was formed again by the flame deposition method so as to fill the waveguide patterner.

In the optical waveguide formed by this method, the upper and lower clad layers have a thickness of 25 μm, and the core layer has a cross section of 8 μm.
It is a rectangle of μm ² with a relative refractive index difference of 0.3% and a wavelength of 1.3.
It had a μm single mode waveguide structure. In addition, these optical waveguides have 250
Eight parallel patterns were formed at a pitch of μm. This pattern had a size of 5 mm × 20 mm, and was formed on a 7.62 cm (3 inch) silicon single crystal substrate in 2 rows × 10 stages at a total of 20 places. The substrate on which the optical waveguide was formed in this way was cut into individual optical waveguide patterns by a dicing saw to form a planar lightwave circuit chip.

At both ends of the upper surface of this planar lightwave circuit chip, a width adjusting top substrate is 5 mm wide and 5 m long.
Two silicon substrates having a thickness of 1 mm and a thickness of 1 mm were fixed by an adhesive so that the end faces and the side faces were aligned. afterwards,
Planar polishing was performed so that the end surface of the planar lightwave circuit chip and the end surface of the thickness adjusting substrate were flush with each other.

On the other hand, a silicon substrate having a width of 5 mm, a length of 6 mm and a thickness of 1.09 mm is prepared for the grooved substrate of the fiber arranging tool, and the width of 240 μm is anisotropically etched on the silicon substrate. Eight V grooves were formed at intervals of 250 μm to complete a grooved substrate. The restraining lid has a width of 5 mm,
It was formed from a silicon substrate having a length of 6 mm and a thickness of 0.97 mm. The optical fibers of the single-mode 8-core optical fiber ribbon are aligned and engaged in the V-grooves of the grooved substrate, fixed with an adhesive while being held by the holding lid, and then the end faces of the grooved substrate and the holding lid are polished. The fiber array tool is completed.

The optical waveguide and the optical fiber are aligned on the fine adjustment stand while the optical power is monitored by abutting the end faces of the two fiber arranging tools on the both end faces of the planar lightwave circuit chip thus completed. Then, an adhesive was applied to the butted portion to fix it (see FIG. 2).

The step between the abutting portions of the planar lightwave circuit chip and the fiber arranging tool was within 20 μm. Also,
The transmission loss due to the axis deviation after bonding and fixing both was 0.1 dB / place or less. The measured values were almost the same at both ends of the lightwave circuit chip.

In the second embodiment of the present invention, a crystalline glass substrate is used as the thickness adjusting upper substrate instead of the silicon substrate. This crystalline glass substrate has a thickness of 1 mm and a transmittance of 20% or more in the wavelength range of 350 nm to 450 nm. A crystalline glass substrate was used instead of the silicon substrate as the grooved substrate of the fiber array tool. V-groove processing was performed using an ultra-precision grinder. The planar lightwave circuit chip and the fiber arranging device were adhered by using an ultraviolet curable adhesive.

The second embodiment also shows the same connection characteristics as the first embodiment. Further, when a heat cycle test at −10 to 60 ° C. was performed, loss fluctuation during the test was ± 0.2 dB or less, and residual loss was ± 0.1 dB or less.

In the embodiment of the present invention, the fiber arranging tool is composed of the grooved substrate having the V groove and the holding lid.
This fiber arranging tool may have a structure in which holes for fiber fixing are arranged by being manufactured by transfer molding using a plastic resin.

[0021]

According to the present invention, as described above, since the upper substrate for adjusting the thickness is provided on the optical waveguide of the planar lightwave circuit chip, the abutting portion between the planar lightwave circuit chip and the fiber arranging tool is provided. Since the difference in level is small, and therefore the adhesive does not accumulate unevenly at this abutting part, there is no imbalance in stress due to thermal contraction during curing of the adhesive and thermal expansion and contraction due to changes in the environment. It is possible to suppress axial misalignment between the optical waveguide of the planar lightwave circuit chip and the optical fiber of the fiber array tool. In addition, the number of butt end faces to be bonded between the planar lightwave circuit chip and the fiber arraying tool is increased, and the bonding strength is improved.

[Brief description of drawings]

FIG. 1 is an overall perspective view of an optical waveguide module according to the present invention.

FIG. 2 is a perspective view showing an exploded state of one half of the optical waveguide module shown in FIG.

FIG. 3 is a vertical sectional view of one half of a conventional optical waveguide module.

[Explanation of symbols]

 10 Optical Waveguide Module 12 Planar Substrate 14 Optical Waveguide 16 Planar Lightwave Circuit Chip 18 Fiber Ribbon 20 Grooved Substrate 22 Suppression Lid 24 Fiber Arrangement Tool 26 Upper Substrate for Thickness Adjustment

Claims (1)

[Claims] 1. A planar lightwave circuit chip having an optical waveguide on a flat substrate, and a fiber arranging tool for arranging and holding optical fibers of an optical fiber ribbon connected to the optical waveguide of the lightwave circuit chip. An optical waveguide module in which a planar lightwave circuit chip and the fiber arranging device are bonded to each other by aligning the optical waveguide and the optical fiber of the fiber arranging device so that the planar lightwave circuit chip sandwiches the optical waveguide. An optical waveguide module, further comprising: a thickness adjusting upper substrate provided on the flat substrate, wherein the upper substrate is abutted against and bonded to the fiber arranging tool.