CN101546014A - Large-bandwidth Y-branch power splitter based on mode gradual change principle - Google Patents

Abstract

The large-bandwidth Y-branch power splitter based on the mode gradient principle of the present invention includes an input optical waveguide and two output optical waveguides; the input optical waveguide includes connected straight waveguides and tapered optical waveguides, and each output optical waveguide includes connected The straight waveguide and S-shaped tapered optical waveguide, the tapered optical waveguide of the input optical waveguide is inserted between the S-shaped tapered optical waveguides of the two output optical waveguides in parallel, the tapered optical waveguide of the input optical waveguide and the two output optical waveguides The overlapping region of the S-shaped tapered optical waveguide is a mode gradient region, forming a Y-shaped composite optical waveguide. Through the mode transition region, the fundamental mode of the input optical waveguide is gradually transformed into a field distribution with two peaks, which are respectively output from the output optical waveguide, realizing low-loss power distribution. The invention has a simple structure and has ultra-low loss in the bandwidth range of 1.2 μm to 1.8 μm.

Description

A Large Bandwidth Y-branch Power Splitter Based on Mode Gradual Principle

technical field

The invention relates to a Y-branch power splitter, in particular to a large-bandwidth Y-branch power splitter based on the principle of mode gradual change.

Background technique

In addition to the backbone network and the metropolitan area network, the fiber-to-the-home access network has gradually become an important development and construction direction of optical communication. Fiber-to-the-home (FTTH) can provide users with extremely rich bandwidth. It is an ideal access mode and the best way to solve the "last mile" for future optical fiber communication systems, and will become a symbol of a new generation of broadband networks. This puts forward new technical requirements for optical devices and opens up a new application field for them.

In the fiber-to-the-home access network system, the power splitter is a necessary basic component. For the power divider applied to FTTH, the most important feature is to have a super wide bandwidth (1250nm ~ 1700nm). Compared with other discrete devices, the integrated Y-branch power divider has outstanding advantages such as high integration, small size, high stability, and mass production. The structure of a common integrated Y-branch power splitter (as shown in FIG. 1 ) includes an input waveguide 1 , a tapered region 50 and two S-shaped output optical waveguides 2 and 3 connected in sequence. However, this conventional structural design includes a sharp corner 51 . Due to the limitation of the manufacturing process, it is difficult to realize the sharp corner 51 in the actual device, which will cause a large loss. In order to overcome the sharp angle problem, someone proposed a power splitter based on the coupling of three parallel optical waveguides (Journal of Lightwave Technology, 8(10): 1621, 1990), as shown in Figure 2, in which two output optical waveguides have uniform width, its working principle is based on evanescent wave coupling. However, the evanescent coupling between the input optical waveguide 1 and the output optical waveguides 2, 3 is wavelength sensitive, thus limiting the bandwidth of this power splitter. Some people also use multi-mode interference (MMI) power divider structure, as shown in Figure 3. Although the sharp corners in common Y-branch power splitters can be avoided, the MMI power splitter bandwidth is still limited due to the wavelength sensitivity of the self-imaging in the MMI coupler.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, and propose a large-bandwidth Y-branch power divider based on the principle of mode gradual change, so as to solve the problem of too small bandwidth of a common Y-branch power divider.

The large-bandwidth Y-branch power splitter based on the mode gradient principle of the present invention includes an input optical waveguide and two output optical waveguides; the input optical waveguide includes straight waveguides and tapered optical waveguides connected, and the tapered optical waveguide is connected with the straight waveguide. The width from the junction to the end of the waveguide changes slowly to meet the mode gradient condition. Each output optical waveguide includes a connected straight waveguide and an S-shaped tapered optical waveguide. The S-shaped tapered optical waveguide is from the junction with the straight waveguide to the end. The width of the part changes slowly to meet the mode gradient condition. The tapered optical waveguide of the input optical waveguide is inserted between the S-shaped tapered optical waveguides of the two output optical waveguides in parallel, and the tapered optical waveguide of the input optical waveguide and the two output optical waveguides The overlapping region of the S-shaped tapered optical waveguide is a mode gradient region, forming a Y-shaped composite optical waveguide.

The beneficial effects that the present invention has are:

1. Ultra-low loss in a large bandwidth (1.2μm ~ 1.8μm);

2. The structure is simple, the design is convenient, and the manufacturing process requirements are low.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a common Y branch power divider;

Figure 2 is a schematic structural diagram of a power splitter based on the coupling of three parallel optical waveguides;

Fig. 3 is a schematic structural diagram of a multimode interference (MMI) power divider;

Fig. 4 is a schematic structural diagram of a power divider of the present invention;

Fig. 5 is the loss characteristics of the present invention in the range of 1.2 μm to 1.8 μm;

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments.

With reference to Fig. 4, the large-bandwidth Y-branch power splitter based on the mode gradual change principle of the present invention comprises an input optical waveguide 1 and two output optical waveguides 2, 3; the input optical waveguide 1 comprises straight waveguides 10 connected with uniform width And the tapered optical waveguide 11, the width of the tapered optical waveguide 11 changes slowly from the connection with the straight waveguide equal width to the end 12, and satisfies the mode gradient condition, and each output optical waveguide includes a connected straight waveguide 20 with uniform width and S-shaped tapered optical waveguide 21, the width of S-shaped tapered optical waveguide 21 changes slowly from the connection with the straight waveguide 20 equal width to the end 23, satisfying the mode gradient condition, the tapered optical waveguide 11 of the input optical waveguide 1 is parallel Insert between the S-shaped tapered optical waveguides 21 of the two output optical waveguides 2, 3, that is, there is no intersection between each other, the tapered optical waveguide 11 of the input optical waveguide 1 and the S-shaped tapered optical waveguides of the two output optical waveguides 2, 3 The overlapping region of the shaped optical waveguides 21 is the mode transition region 43, and in the mode transition region 43, the input optical waveguide and the two output optical waveguides form a Y-shaped composite optical waveguide.

At the input position of the mode transition area, the mode of the composite optical waveguide is almost the same as the fundamental mode of the input optical waveguide; at the output position of the mode transition area, the mode of the composite optical waveguide is almost the same as the complex fundamental modes of the two output optical waveguides. Through the mode gradient region, the fundamental mode of the input optical waveguide 1 gradually transforms into a field distribution with two peaks, and the two peaks are respectively output from the output optical waveguides 2 and 3, realizing a low-loss power distribution function.

The two output optical waveguides 2, 3 can be distributed symmetrically or asymmetrically with respect to the input optical waveguide 1, correspondingly, a uniform or non-uniform power distribution ratio can be obtained.

A specific embodiment of the present invention is given below. All optical waveguides are SiO ₂ -on-Si buried optical waveguides with a refractive index difference Δ=0.75%. In this example, two output optical waveguides are distributed symmetrically. Its geometric parameters are as follows:

The straight waveguide 10 of the input optical waveguide 1 has a width of 3.5 μm, the width 12 of the end of the tapered optical waveguide 11 is 1.0 μm, and the length 14 is 1300 μm.

The straight waveguide 20 of the output optical waveguide has a width of 6.0 μm, the width 23 of the end of the S-shaped tapered optical waveguide 21 is 1.0 μm, the length 24 of the S-shaped curved part is 2600 μm, and the lateral offset 26 is 6 μm.

Figure 5 shows the optical power output from the output optical waveguide within the entire bandwidth of 1200-1800nm. It can be seen that the present invention can realize low-loss power distribution within a super large bandwidth of 1200-1800nm.

The above-mentioned embodiments are used to illustrate the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (1)

1. the large-bandwidth Y-branch power splitter based on mode gradual change principle is characterized in that comprising an input waveguide (1) and two output optical waveguides (2,3); Input waveguide (1) comprises straight wave guide (10) and the conical optical waveguide (11) that is connected, conical optical waveguide (11) is Zi slowly changing with the junction of the straight wave guide width to the end, satisfy the mode gradual change condition, every output optical waveguide comprises continuous straight wave guide (20) and S type conical optical waveguide (21), S type conical optical waveguide (21) is Zi slowly changing with the junction of straight wave guide (20) width to the end, satisfy the mode gradual change condition, two output optical waveguides (2 of the parallel insertion of conical optical waveguide (11) of input waveguide (1), 3) between the S type conical optical waveguide (21), the conical optical waveguide (11) of input waveguide (1) and two output optical waveguides (2, the overlapping region of S type conical optical waveguide (21) 3) is mode gradual change district (43), forms Y shape composite optical wave guide.

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