JPH06313821A - Optoelectronic integrated circuit - Google Patents

Abstract

PURPOSE: To provide an optoelectronics integrated circuit capable of simply attaining the connection and adjustment of at least two glass fibers in respect to an optoelectronics integrated circuit connected especially to glass fibers. CONSTITUTION: The integrated circuit has a light incident/outgoing face B prevented from being reflected, an waveguide W connecting at least two end parts to the face B and one or more areas A, M having pn junction or pin junction in the waveguide W.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to optoelectronic integrated circuits, and more particularly to integrated circuits for simple chip-fiber coupling in optical control elements.

[0002]

BACKGROUND OF THE INVENTION In the transmission section of optoelectronic communication technology, there is the problem of connecting optical semiconductor devices to glass fiber waveguides by means of two chip-fiber couplings, for example optical modulators, switches and amplifiers. . Optical amplifiers in particular require chip-fiber couplings with high reproducible coupling efficiency combined with very little back reflection.

[Electronic Letters (Electron
ics Letters) 27 "pp. 1845-1846 (199)
1 year) R. Boudreau et al. Describes a double-sided connection of glass fiber to an optical amplifier. The fiber must be aligned with respect to the amplifier waveguide with a tolerance in the region of 1 μm or less. In particular, the position of the first adjusted fiber must be maintained during the alignment of the second fiber.

The paper by Y. Tamura et al., "The 16th European Optical Communications Conference 1990 (ECOC'90)", describes an amplifier module containing an optical circulator.

[Electronic Letters (Electron
ics Letters) 25 "pp. 242-243 (1989)
(1) Cha. Et al., Describe an optical amplifier with a waveguide end face embedded for antireflection.

[Electronic Letters (Electron
ics Letters) 27 "pp. 1747-1748 (199)
1 year) P.Jduthie et al.
A 4 × 4 switching matrix with directional couplers connected via an arc of ˜20 mm is described.

The N. Bar-Chaim article describes an aluminum-gallium-arsenic-laser diode having a quantum-well structure with a half-ring geometry.

[Photon Technology Letters (Ph
oton.Technol.Letters) 2 "88-90 (1990)
(TLKoch) et al. Describe a laser diode with a multiquantum-well structure in the indium-gallium-arsenic / indium-gallium-phosphide system with tapered waveguides. .

[Electronic Letters (Electron
ics Letters) 27 "132-134 (1991)
Year) Saul (JBDSoole) and other papers "1.5 μm
"A Monolithic InP-Based Grating Spectrometer for Wavelength Division Multiplexing Systems", describes a wavelength demultiplexer on an InP chip. In this demultiplexer, many ridge waveguides are arranged in parallel with each other, and one end of each of them is opened to the same light incident / emission surface. The other end of each is directed to a diffraction grating that respectively reflects the incident light rays back into the waveguide.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide an optoelectronic integrated circuit, in particular for coupling with glass fibers, which allows easy connection and adjustment of at least two glass fibers. To provide.

[0011]

This problem is solved by an optoelectronic integrated circuit having the features of claim 1. Embodiments are listed in claims 2 and below.

[0012]

In the integrated circuit according to the present invention, the waveguides which are connected to the same light incident / emission surface at the end portions are provided.

Therefore, the side surface of the integrated circuit, which is provided for light incidence, is also used as an emission surface, and antireflection means, for example, an antireflection layer is provided. Therefore, the glass fibers to be connected to the integrated circuit can be connected to the same side of the integrated circuit. If the integrated circuit is assembled on a sub-carrier, this sub-carrier may be provided with groove-like cuts for receiving and fixing the glass fibers. Thus, a simple and easy mass-reproducible adjustment of the glass fibers to be spliced is possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An integrated circuit according to the present invention will be described below with reference to FIGS.

FIG. 1 shows an integrated circuit according to the invention with a doubly bent waveguide W in a perspective view of the surface viewed from the side of the light incident / emission surface B. Regions A and M provided for supplying energy are arranged in the waveguide W. For this purpose pn or pin junctions are arranged in the waveguide in these regions. The energy is provided in the form of optical energy, which can be done, for example, by illumination of this region from above or by light guided into the waveguide. Energy can also be supplied in the form of electrical energy via contacts provided on these areas. In the drawing, these areas are shown as amplifier A and modulator M as an example. In the waveguide of FIG. 1, an amplifier A is located in the center and a modulator M is located in each of the two arcs. However, it is also possible to provide a modulator or a directional coupler instead of the amplifier (switch), respectively. The center end of the waveguide is for light incidence,
Both ends located on the sides are provided for light emission (implied by the arrow). The radius R of the waveguide arc is also entered.

FIG. 2 shows an integrated circuit having three arcs and thus also four waveguides, two of which are provided for light incidence and two for light emission. . The waveguide according to FIG. 2 is provided with four amplifiers A. The integrated circuit according to FIG. 1 forms a 1 × 2 matrix with optical switches in the form of y-forks. The integrated circuit according to FIG. 2 forms a 2 × 2 matrix, which allows a matrix-free construction. In order to improve the coupling between the glass fiber to be connected to the integrated circuit and the integrated circuit, a waveguide taper is provided at each opening of the waveguide W, as described in the above-mentioned publication by TLKnoch et al. It can be arranged in the light entrance / exit surface B. Waveguides are used for the light incidence / integration of integrated circuits, as described in the above-mentioned publications by Cha.
It may be terminated just before the emission surface B, or the end surface may be antireflection by a dielectric layer.

The bent region (arc) of the waveguide W is preferably constructed as a buried heterostructure (BH).
Particularly suitable for guiding light into the bent waveguide region are optical modulators (as shown in the drawings) or electrically pumped optical amplifiers with BH structures. . This is because those waveguide cores have a particularly high refractive index compared to the surrounding semiconductor material. The resulting relatively strong wave guidance makes especially small the radiation losses that might otherwise occur due to the curvature. FIG. 3 is a diagram showing the calculation result of the radius R of the semicircular waveguide arc in relation to the thickness D of this waveguide, in which case the width d and the material composition ( Band edge wavelength) is selected.
In doing so, a waveguide core consisting of indium-gallium-arsenide-phosphide embedded in indium-phosphide was the basis. As is clear from this diagram, a radius R of 1 mm or less is possible for a maximum possible radiation loss of 0.1 cm ^-1 . Instead of an indium-gallium-arsenide / indium-phosphide-BH structure, the device according to the invention comprises a ridge waveguide including a quantum-well layer, or an aluminum-gallium-
The material composition may include arsenide, indium-gallium-arsenide or gallium-arsenide.

FIG. 4 is a perspective view of an optoelectronic integrated circuit according to the present invention having a subcarrier S on which at least two fibrous optical waveguides (glass fibers) are mounted. The electrical drive of the integrated circuit IC takes place via the contacts K, K1, K2, K3 and K4. These contacts are conductively coupled, for example, to the region of the waveguide where the pn or pin junction is provided (eg amplifier A or modulator M). The subcarrier S is made of silicon, for example, and contains two groove-shaped notches V for the mutual alignment of the glass fibers G, which preferably have a V-shaped cross section.

The light coupled into the waveguide from one glass fiber G is guided in the arc through the integrated circuit IC to the other glass fiber G, at which time the turning angle is 180 °.
Is. An advantage of the present invention is that the distance between both ends of the waveguide W and the distance between both glass fibers on the light incident / emission surface B of the integrated circuit can be maintained with high accuracy. This significantly reduces the alignment error due to the coupling between the integrated circuit and the glass fiber during manufacture. Therefore, the cost for coupling between the input and output glass fibers and the integrated circuit is significantly reduced in the integrated circuit according to the invention. This is because the entrance waveguide and the exit waveguide are arranged on the same chip end face. This is especially true
It is useful when more than two glass fibers should be spliced. Another advantage of the present invention is that the footprint of the integrated circuit is reduced due to the particularly small radius of curvature for the waveguide, which is made possible by strong wave guidance in the buried heterostructure.

FIG. 5 corresponds to the integrated circuit of FIG. 2, but
An integrated circuit according to the invention is shown in which the waveguide has one crossing point. Compared to the circuit of FIG. 2, this integrated circuit of the 2 × 2 switching matrix has the waveguide ends that are open to the light incident / emission planes located closer to each other,
It also has the advantage that the width of the integrated circuit can be kept smaller. The end of the waveguide W is formed by a two-dimensional taper T in the embodiment shown in FIG. Thereby, a larger cross section of the glass fiber to be coupled compared to the waveguide extending in the integrated circuit can be adapted to this smaller cross section of the waveguide.

FIG. 6 shows an integrated circuit according to the invention as a 4 × 4 switching matrix, in which the amplifier switch can be replaced by a modulator or a directional coupler, respectively. A is entered. The portions defined by the dashed-dotted rectangle form a 2 × 2 switching matrix.

In the integrated circuit shown in FIG. 7, the waveguide arc is replaced by a straight section having one amplifier A and two turning mirrors U contained therein. Each of these turning mirrors U causes a change in direction of approximately 90 °. A two-dimensional taper T is used as an end portion of the waveguide opening to the light incident / emission surface B. However, the turning angle of the turning mirror U may deviate from 90 °, whereby the angle C from the normal to the light incident / exiting surface B is changed.
One or both waveguide end orientations that deviate by only one are obtained. Alternatively, it is possible to use more than two turning mirrors. A V-shaped arrangement is obtained by terminating the two straight sections of the waveguide in a turning mirror which causes substantially back reflection of the light rays. It is also possible to place a straight section of the waveguide between two arcs that cause a change in waveguide direction of only 90 °. A combination of turning mirrors, for example on one side for a 90 ° arc and on the other side for a change of direction of only 90 ° is also conceivable.
A number of possibilities are likewise provided for the antireflection of the light-incident / emission surface B, of which the antireflection layer is considered to be particularly advantageous.

FIG. 8 shows an integrated circuit corresponding to FIG. 1 in which the central waveguide end is arranged at a distance a from the light incident / emission surface B. In this case, it is advantageous if the energy-supplied region (in this case amplifier A) extends to the end of this waveguide section. The light incident / exiting surface B may be covered with an antireflection layer E as shown in FIG. In the example of FIG. 9, all the waveguides are terminated in front of the antireflection layer E with a distance a. The waveguide end is a passive section of the waveguide W in this example. These embodiments are advantageous in terms of connecting glass fibers. Similarly, in the embodiment of FIG. 7 with the turning mirror U, one or more waveguide ends may be spaced from the light incident / emission surface B.

[Brief description of drawings]

FIG. 1 is a perspective view of an integrated circuit according to the present invention having a waveguide guided in two arcs.

FIG. 2 is a perspective view of an integrated circuit having a waveguide guided and branched in three arcs.

FIG. 3 is a diagram showing possible curvature radii for a waveguide arc in relation to the thickness of the waveguide, its width and the material used.

FIG. 4 is a perspective view of an integrated circuit mounted on a subcarrier having glass fibers coupled together.

5 is a perspective view of an integrated circuit corresponding to the integrated circuit of FIG. 2 except for waveguide crossovers.

FIG. 6 is a schematic diagram of an integrated circuit according to the present invention as a 4 × 4 switching matrix.

FIG. 7 is a perspective view of an integrated circuit having two turning mirrors.

FIG. 8 is a perspective view of the integrated circuit corresponding to FIG. 1 with the waveguide sections terminating at a distance in front of the light incident / emission surface.

9 is a perspective view of the integrated circuit corresponding to FIG. 2 with all waveguide ends spaced at the light entrance / emission surface.

[Explanation of symbols]

 A amplifier B light incidence / emission surface E antireflection layer M modulator U turning mirror W waveguide IC integrated circuit

Claims (10)

[The claims] 1. A light incidence / emission surface (B) having antireflection, a waveguide (W) having at least two ends guided to the light incidence / emission surface (B), and An optoelectronic integrated circuit having at least one region (A, M) having a pn junction or a pin junction in a waveguide. 2. The direction change of the waveguide (W) required to guide the end of the waveguide (W) to the light incident / exiting surface (B) is 1.
Integrated circuit according to claim 1, characterized in that it is produced by at least one arc in a waveguide (W) having a radius (R) of less than mm. 3. The direction change of the waveguide (W) necessary for guiding the end of the waveguide (W) to the light incident / exiting surface (B) is produced by at least one turning mirror (U). The integrated circuit according to claim 1, wherein the integrated circuit comprises: 4. A subcarrier (S) is provided, and a groove for fixing the glass fiber (G) at an interval between ends of the subcarrier (S) communicating with the light incident / emission surface of the waveguide (W). Integrated circuit according to one of the preceding claims, characterized in that it has a notch (V). 5. The integrated circuit according to claim 1, wherein the waveguide (W) is constructed in a buried heterostructure. 6. The integrated circuit according to claim 1, wherein the waveguide (W) is a ridge waveguide. 7. The integrated circuit according to claim 1, wherein the waveguide has a quantum well structure. 8. The waveguide (W) is provided with a taper (T) at each end communicating with the light incident / exiting surface to improve coupling to a glass fiber. An integrated circuit according to any one of 1. 9. At least one part of the waveguide (W) guided to the light incident / emission surface (B) is from or to the light incident / emission surface (B). Integrated circuit according to one of the preceding claims, characterized in that it terminates at a distance (a) from the applied antireflection layer (E). 10. Integrated circuit according to claim 1, characterized in that the region having a pn or pin junction is an amplifier (A) or a modulator (M).