KR100256702B1 - Integrated semiconductor optic amplifying system with high saturation power - Google Patents

Abstract

PURPOSE: A semiconductor optical amplifier system is to enhance an optical saturation characteristic and to integrate the semiconductor optical amplifier system on one chip. CONSTITUTION: An optical division unit(7) divides an optical signal which is inputted through an input waveguide(6) into N number of optical signals, where N is an integer. A semiconductor optical amplification unit(8) receives and amplifies the N number of the optical signals. An optical combination unit(9) receives the outputs of the optical amplification unit and outputs the received optical signal to an output waveguide(10). The optical amplification unit includes N number of semiconductor optical amplifiers. The optical division unit is implemented with one of 1 by N multi-mode interference optical divider and 1 by N Y-type optical divider. The optical combination unit is implemented with one N by 1 multi-mode interference optical combiner and N by 1 Y-type optical combiner.

Description

Integrated semiconductor optical amplification system with high saturation output

TECHNICAL FIELD The present invention relates to the field of semiconductors and, more particularly, to semiconductor optical amplification systems used in optical communication systems.

Amplification does not occur indefinitely in all the media where the amplification of the input optical signal occurs, and when the amplified signal has an output density higher than a certain level, it is no longer amplified.

Even in a semiconductor waveguide type optical amplifier, when the input optical signal travels in the waveguide direction and the intensity of the amplified signal exceeds a certain level, the gain decreases and the output does not increase any more. The light output at this time is defined as the saturation output. If the intensity of the input signal is small, output saturation does not occur, but if the intensity is large, output saturation occurs. Since all amplification materials contain this gain saturation, efforts to optimize the structure of the device are required to improve the saturation characteristics.

A conventional optical amplifier structure presented as part of an effort to improve such a saturation phenomenon is schematically illustrated in FIG. 1.

As shown, the optical amplifier having a high saturation output according to the prior art has a structure that increases the total saturation output by forming a wide active layer 3 while maintaining the single mode by increasing the width of the waveguide. In this structure, the saturation output per unit volume remains unchanged, but the total saturation amount becomes large. The optical amplifier of such a structure can improve the saturation characteristics, but the conversion of the mode size makes it impossible to integrate a single chip with other single mode waveguides and there is a problem that only the optical fiber using a lens can be modularized.

Reference numeral '1' represents an active region, '2' represents a clad region, '4' represents an upper clad layer, and '5' represents a substrate clad layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor optical amplification system capable of integration into a single chip and improving optical saturation output characteristics.

That is, the present invention is to implement an optical amplification system that can be integrated with the optical waveguide of the other function because the waveguide of the input / output stage is formed in a single mode while improving the saturation characteristics.

1 is a schematic configuration diagram of a conventional semiconductor optical amplifier.

2 is a conceptual diagram of a semiconductor optical amplification system having a high saturation output according to the present invention.

3 is a conceptual diagram of an integrated optical amplification system according to a first embodiment of the present invention;

4 is a schematic structural diagram of an optical amplification integrated system according to a second embodiment of the present invention;

5 is a conceptual diagram of an integrated optical amplification system according to a third embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

1: active area 2: cladding area

3: active layer 4: upper clad layer

5 substrate cladding layer 6 input waveguide

7: 1 x N MMI (Multimode Interference) Optical Separator

8: semiconductor amplifier 9: N x 1 MMI optocoupler

10: output waveguide

The semiconductor optical amplification system provided by the present invention comprises: an optical separation unit for separating an optical signal input through an input waveguide into N (natural numbers) optical signals; A semiconductor optical amplifier for amplifying each of N optical signals input from the optical separator; And an optical coupling unit configured to receive the output of the optical amplifier and output the output signal as a single optical signal to an output waveguide.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 shows a conceptual configuration of a semiconductor optical amplification system having a high saturation output according to the present invention.

As shown, the optical amplification system of the present invention includes N semiconductor optical amplifiers 8, 1 x N multimode interference (MMI) optical splitters 7, and N x 1 MMI optical couplers provided on the waveguide. 9)

First, the optical signal input to the input waveguide 6 is separated into N optical signals through a 1 x N MMI optical splitter 7, and each optical signal is incident on the N semiconductor optical amplifiers 8, respectively. Amplify.

Next, each of the amplified optical signals are combined by passing through the N x 1 MMI optical coupler (9), and transmitted to one output stage waveguide (10).

As described above, in the present invention, the input signals are divided into N and input to the N optical amplifiers 8, respectively, so that the output is not saturated even if the intensity of the input signal is increased, thereby increasing the saturation output of the entire amplifier by N times. You will get If there is no semiconductor optical amplifier 8 and is connected by a waveguide of the same length, light of the same intensity as the input signal is waveguided at the output terminal when the additional loss of the waveguide itself is ignored. The optical amplifier of the present invention has an advantage of being integrated into a single chip because the waveguide of the input / output stage is a single mode waveguide while improving the saturation output characteristic by N times.

FIG. 3 illustrates a conceptual configuration of an optical amplification system according to a first embodiment of the present invention, and illustrates a structure in which an S-type curved waveguide and two semiconductor amplifiers 33a and 33b are integrated. Reference numeral '31' denotes an input waveguide, '32' denotes a 1 × 2 MMI optical splitter, '34' denotes a 2 × 1 MMI optical coupler, and '35' denotes an output waveguide. This has the effect of doubling the saturation output of the amplifier.

Here, the S-type waveguide is symmetrically inserted so that the optical signal separated by the 1 × 2 MMI optical splitter 32 has the same phase, and the S signal is inputted to the 2 × 1 MMI optical combiner 34 so that the optical signal has the same phase. Type waveguides are inserted symmetrically.

4 is a diagram illustrating a conceptual configuration of an optical amplification system according to a second embodiment of the present invention, and showing an integrated structure of an S-shaped curved waveguide and four semiconductor amplifiers 43a, 43b, 43c, and 43d. have. As shown, the optical signal input from the input waveguide 41 is separated into two optical signals in the 1 × 2 MMI optical splitter 42, and these are respectively separated by two optical signals in the 2 × 1 MMI optical splitters 43a and 43b. Separate into optical signals. Subsequently, the four optical signals amplified by the four semiconductor amplifiers 43a, 43b, 43c, and 43d, respectively, are combined by two 2x1 MMI optical couplers 45a and 45b, respectively, and the combined signals are again 2x1. It is combined in the MMI optical coupler 46 and output through the output waveguide 47 as one optical signal. The optical amplification system of this structure has the effect of increasing the saturation output of the entire amplifier by four times than conventional.

Here, the S-type waveguides are symmetrically inserted so that the optical signals separated by the 1 × 2 MMI optical splitters 42, 43a, 43b have the same phase, and are inserted into the 2 × 1 MMI optical couplers 45a, 45b, 46. The S-type waveguide is symmetrically inserted so that the input optical signal has the same phase.

5 is a diagram illustrating a conceptual configuration of an optical amplification system according to a third exemplary embodiment of the present invention, in which an S-shaped curved waveguide and eight semiconductor amplifiers 55a to 55h are integrated.

As shown, eight optical signals are inputted through seven 1 × 2 MMI optical splitters 52, 53a, 53b, 54a, 54b, 54c, and 54d having one optical signal input to the input waveguide 51 as three stages. The optical signal amplified by the eight semiconductor amplifiers 55a to 55h is then passed through seven 2x1 MMI optical couplers 56a, 56b, 56c, 56d, 57a, 57b and 58 which are also configured in three stages. Combined and output through the output waveguide 59 as a single optical signal. In this case, there is an effect of increasing the saturation output of the entire amplification system by 8 times than in the prior art.

As described above, the present invention can be integrated into a single chip because the waveguide of the input / output stage is a single mode waveguide while improving the saturation output characteristics.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

Semiconductor optical amplifiers have been applied to systems for various purposes, but due to gain saturation, they are limiting their applicability. When the optical amplifier of the present invention is used, it is expected that the design of the optical integrated circuit can be diversified and the development of a high performance optical functional device can be achieved.

Claims (6)

An optical separation unit for separating the optical signal input through the input waveguide into N (natural numbers) optical signals; A semiconductor optical amplifier for amplifying each of N optical signals input from the optical separator; And An optical coupling unit receiving the output of the optical amplifier and outputting it as an optical signal to an output waveguide; Integrated semiconductor optical amplification system comprising a. The method of claim 1, The optical amplifier Integrated semiconductor optical amplifier system comprising N semiconductor optical amplifier. The method according to claim 1 or 2, The optical separation unit An integrated semiconductor optical amplification system consisting of 1xN multimode interference optical separation means or 1xN Y-type optical separation means. The method according to claim 1 or 2, The optical coupling portion An integrated semiconductor optical amplification system consisting of Nx1 multimode interfering optical coupling means or Nx1 Y-type optical coupling means. The method of claim 3, wherein The 1 × N multimode interference optical separation means Integrated semiconductor light including an S-type waveguide symmetrically inserted so that an optical signal separated by the 1 × 2 multimode interference optical splitter configured in one or multiple stages and the optical signal separated by the 1 × 2 multimode interference optical splitter have the same phase. Amplification system. The method of claim 4, wherein The N × 1 multimode interfering optical coupling means Integrated semiconductor optical amplification comprising a 2x1 multimode interfering optical coupler composed of one or multiple stages and an S-type waveguide symmetrically inserted such that the optical signal input to the 2x1 multimode interfering optical coupler has the same phase. system.

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