JPS5856989B2 - Optical branching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical add/drop multiplexer using a distributed feedback type semiconductor amplification element having a double heterojunction structure as an optical drop/add element.

Fiber optic equipment suffers from crosstalk.
)'L Since it can be easily made small and has good space utilization, it is expected to be applied to data buses of electronic computers and has been actively developed.

By the way, in this lightning fiber device, branching of an optical signal from an optical fiber and insertion of an optical signal into the optical fiber are regarded as important basic technologies.

Conventionally, various types of optical fiber devices have been known in which optical branching or adding devices are inserted between optical fibers to drop or add optical signals.
Both methods have the disadvantage of large losses during branching and insertion of optical signals.

The present invention has been devised to eliminate these drawbacks, and provides an optical add/drop multiplexer that can minimize loss of optical signals during drop/add of optical signals.

Hereinafter, one embodiment of the present invention will be described with reference to Eko.

In the figure, numeral 1 is a distributed feedback semiconductor amplification element having a double heterojunction structure.

This semiconductor amplifying element 1 has n
-Ca gog Al□, 1As layer 4 and n-Ga
The As layer 5 is sequentially bonded outward, and the pGao, 9 Al□, As layer 6 and p-GaAs layer 7 are sequentially bonded outward to the other side of the GaAs active layer 2 to form a double heterojunction structure.

And the n-Ga□, gAlo, IAs layer 3 and n-Gao, 7 A70. The BAs layer 4 is used as an optical waveguide, and a wafer structure 8 having periodic irregularities along the optical waveguide is formed on the joint surface of both layers 3 and 4.

The length of the ridge structure 8 is limited to a predetermined length so that the semiconductor amplifying element 1 does not oscillate due to distributed feedback due to Bragg reflection.

That is, the length of the ridge structure 8 is limited so that the semiconductor amplifying element 1 does not oscillate and emit light by itself.

Further, in the semiconductor amplifying element 1, a negative electrode contact 9 having an opening in the center is bonded to the outside of the nGaAs layer 5, and a positive electrode contact 10 is bonded to the outside of the p-GaAs layer 7, and each of the contacts A DC voltage is applied between 9 and 10.

Eleventh electrodes are provided on both end faces of the optical waveguide of the semiconductor element 1, respectively.
The second optical fibers 11 and 12 are bonded with transparent epoxy resin, and the third optical fiber 13 is bonded to the opening of the negative electrode contact 9 of the semiconductor amplification element 1 with transparent epoxy resin.

The semiconductor amplifying element 1 has an equivalent refractive index (phase velocity in vacuum/'phase velocity in an optical waveguide) &n, where the periodic interval A of the unevenness of the ridge structure 8 is λ, and the wavelength of light is λ.

A=-Xλ so that the light radiates perpendicularly to the optical waveguide when closed.

(where m is an integer). In such a configuration, if the semiconductor amplification element 1 is operated at a level below the oscillation operation level, the semiconductor amplification element 1 has a function as an optical amplifier, and thus acts as an optical branching or adding element.

That is, the light transmitted from the first optical fiber 11 side is branched to the third optical fiber 13 side by the five-way structure 8 of the semiconductor amplification element 1.

Furthermore, when the light transmitted from the second fiber 12 side enters the semiconductor amplification element 1, it is amplified and transferred to the second optical fiber 1.
1 side, and is also branched to the third optical fiber 13 side by the ridge structure 8 of the semiconductor amplification element 1 .

Thus, the semiconductor amplifying element 1 functions as a branching element.

In this case, the light is branched from the first optical fiber 11 via the semiconductor amplification element 1 to the second and third optical fibers 12.13, or conversely, the light is branched from the second optical fiber 12 via the semiconductor amplification element 1. first and third optical fibers 11.1
Since the light branched into 3 is hardly attenuated by the amplification effect of the semiconductor amplification element 1, the loss at the time of branching can be extremely reduced.

Further, the light inserted through the third optical fiber 13 is split by the ridge structure 8 of the semiconductor amplification element 1, one of which is transmitted to the first optical fiber 11 side, and the other is transmitted to the second optical fiber 11 side. The signal is transmitted to the fiber 12 side.

Thus, the semiconductor amplification element 1 acts as an insertion element.

In this case, the light branched from the third optical fiber 13 via the semiconductor amplification element 1 to the eleventh and second optical fibers 11 and 12 is hardly attenuated by the amplification effect of the semiconductor amplification element 1, so It is possible to minimize the loss in time.

As described above, according to the present invention, a distributed feedback semiconductor amplifier element having a ridge structure of a predetermined length and a double heterojunction structure can be used as an optical branching or adding element by operating it below the oscillation operation level. Therefore, it is possible to provide an optical add/drop multiplexer that can suppress optical signal loss during drop/add of optical signals.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the present invention. 1...Distributed feedback semiconductor amplification element, 80190
1. Always structure, 11, 12, 13... optical fiber.

Claims (1)

[Claims] 1. The GaAlAs layer forming the optical waveguide has a wafer structure with periodic irregularities along the optical waveguide, which is limited to a length that prevents the light introduced into the optical waveguide from oscillating due to distributed feedback due to Bragg reflection. Distributed feedback type having a double heterojunction structure, which amplifies the introduced light along the optical waveguide and radiates the light in a direction perpendicular to the optical waveguide due to the diffraction effect of the ridge structure. Consists of a semiconductor amplification element and optical fibers connected to the optical input and output end faces of this semiconductor amplification element,
An optical add/drop multiplexer, characterized in that the light introduced into the optical waveguide is branched or multiplexed/added by operating the semiconductor amplification element below its oscillation operation level.