JP3112105B2 - WDM light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a high multi-wavelength light source of multiplicity in compact.

[0002]

2. Description of the Related Art A typical structure of a conventional wavelength multiplex light source is shown in FIG. In the figure, 1 is a semiconductor substrate for a gain waveguide, 2 is a semiconductor substrate for a passive waveguide, and a plurality of DFBs (distributed feedback types) having different oscillation wavelengths are provided on the semiconductor substrate for a gain waveguide.
A laser 3 is formed, and a multiplexing waveguide 4 for multiplexing light from each DFB laser 3 is formed on the semiconductor substrate 2 for a passive waveguide. In such a semiconductor light source,
Light of a number of wavelengths oscillated by each DFB laser 3 is multiplexed by the multiplexing waveguide 4 and output from its output end 4A.

[0003]

In the above-mentioned conventional semiconductor light source, it is necessary to arrange DFB lasers 3 having different oscillation wavelengths according to the multiplicity. That is, each DFB laser 3
However, there is a problem that it is necessary to manufacture the gratings with different pitches. When fabricating such a grating, each grating pattern must be drawn by an electron beam exposure method, which is a major obstacle in terms of manufacturing time and cost. Also,
The multiplexing waveguide 4 for multiplexing light of a large number of wavelengths has a multiplexing loss in principle when the output waveguide is a single mode waveguide, and 1 / in the case where the n channels are multiplexed. There is a problem that only n powers are combined. Further, when this light source is operated, there is a problem that the oscillation wavelength shifts due to the heat generated by the injected carrier, and it is impossible to operate the light source while fixing the wavelength of each channel.

In view of such circumstances, the present invention arranges the oscillation wavelengths of a large number of wavelength multiplexed light sources with high precision at equal intervals, and operates the light sources of individual channels so as not to affect other channels. and an object thereof is to <br/> provide a multi-wavelength light source.

[0005]

A semiconductor optical device according to the present invention that achieves the above object has an arrayed waveguide composed of a plurality of waveguides having a delay time difference, and is provided at both ends of the arrayed waveguide. A slab waveguide having a lens effect for converging light from a plurality of waveguides of the arrayed waveguide on a focal plane constitutes an arrayed waveguide grating, and one slab waveguide of the arrayed waveguide grating is formed. A plurality of gain waveguides are connected to the focal plane, and an input / output waveguide is connected to the other slab waveguide.
A cavity having a filter characteristic is configured . [Claim 2] is claim 1
A slab waveguide having a lens effect is composed of a fan-shaped slab waveguide.
It is characterized by having done.

[0006]

The array waveguide grating having the above-described structure functions as a wavelength selecting element. That is, this arrayed waveguide grating selects a wavelength according to the connection position of the focal plane of one of the slab waveguides, and a plurality of gain waveguides connected to the focal plane oscillate at the transmission wavelength at each connection position. I do. Then, the light of each wavelength is multiplex-coupled to the input / output waveguide connected to the focal plane of the other slab waveguide. On the other hand, if a wavelength-division multiplexed signal is input from the input / output waveguide, the arrayed waveguide grating acts as a duplexer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 is a block diagram for explaining an embodiment of a wavelength division multiplexed light source according to the present invention.
1B denotes a semiconductor substrate for a gain waveguide, and 12 denotes a semiconductor substrate for a passive waveguide sandwiched between the semiconductor substrates for gain waveguides 11A and 11B. Further, fan-shaped slab waveguides 13A, 13A having a lens effect are provided at the ends of the semiconductor substrate 12 for passive waveguide.
3B is formed. Fan-shaped slab waveguides 13A, 13
B is formed so that the fan-shaped focal planes 14A and 14B on the essential side are respectively aligned with the end faces of the semiconductor substrate 12 for passive waveguide, and the arcuate surfaces 15A and 15B opposite to the focal planes 14A and 14B are connected to each other. Are connected by a plurality of arrayed waveguides 16 having a fixed length difference between the respective waveguides. On the other hand, a plurality of gain waveguides 17 having a normal semiconductor structure, which are connected to the focal plane 14A of the fan-shaped slab waveguide 13A, are formed on the semiconductor substrate for gain waveguide 11A. On the substrate 11B, one output waveguide 18 connected to the focal plane 14B of the fan-shaped slab waveguide 13B is formed. In the drawing, reference numeral 19 denotes a total reflection corner mirror provided at a corner portion of the arrayed waveguide 16.

Here, the fan-shaped slab waveguide 13A, 1
The optical circuit composed of the 3B and the array waveguide 16 is a so-called array waveguide type grating and has the same function as a diffraction grating type multiplexer / demultiplexer. That is, the fan-shaped slab waveguide 1
Different transmission wavelengths of a plurality of gain waveguide 17 connected to the focal plane 14A of different locations 3A, from the gain waveguide 17 for example lambda _1, light of wavelength λ ₂ ... λ _n is oscillated The signal is multiplexed and output to the output waveguide 18 through the array waveguide 16 and the fan-shaped slab waveguide 13B.

[0010] An example in which such an arrayed waveguide type grating is constituted by a glass waveguide is disclosed in Integrated Fhotonic Rese.
arch '91, Post-deadline Papers, PD1-1, "Multi / demult
iplexer for nanometer-spacing WDM using arrayed-wa
veguide grating ", by H. Takahashi et.al. FIG. 2 shows a multiplexing characteristic of this report example.
A 28-channel multiplexer is formed at a channel interval of 1 nm.

In this embodiment, an example will be described in which the arrayed waveguide grating is formed on an InP-based semiconductor substrate. The waveguide width of the arrayed waveguide 16 is 2 μm, the focal length f of the fan-shaped slab waveguides 13A and 13B is 6.2 mm,
If the length difference between the array waveguides 16 is 10 μm, the chromatic dispersion value is dx / dλ = 2 μm / 0.1 nm. Therefore, the focal plane 14 of the fan-shaped slab waveguide 13A
When the gain waveguides 17 having a width of 2 μm or less are arranged in A at a pitch of 2 μm, a cavity having a narrow band filter of 0.1 μm interval is formed. Oscillates at That is, in the configuration example shown in FIG. 1, a wavelength multiplexed light source having 900 or more array waveguides 16, a channel interval of 1 °, and a channel number of 100 or more can be formed on a 1 cm × 2 cm substrate.

Since the gain waveguide 17 of this embodiment usually has a semiconductor laser structure, the gain distribution is very wide,
In the 1.55 μm band, the gain difference is 3 dB or less over a wavelength band of 1000 ° or more. Therefore, in the present embodiment, if the center wavelength region of the gain waveguide 17 is adjusted, 100
Wavelength multiplexed light sources of channels or more can be arranged with high accuracy. In addition, since heat generated during operation does not directly affect the wavelength selection mechanism, there is no problem of crosstalk between channels. Further, in the output waveguide 18, since the focal point is coincident with each wavelength, no multiplexing loss occurs in principle. That is, while the conventional combiner is merely a convergence of optical power, a merger loss occurs, whereas the present invention controls a phase difference due to a wavelength difference, so that a merger loss does not occur.

In the above embodiment, it goes without saying that the output waveguide 18 can be constituted by a gain waveguide. Further, it is preferable to provide a high reflection film on the end face of the gain waveguide 17 in order to reduce reflection loss. Further, fan-shaped slab waveguides 13A and 13B are used as slab waveguides having a lens effect.
Instead, a slab type lens or the like can be used.

In the above embodiment, an example of a wavelength multiplexed light source has been described. However, it is needless to say that the channel can be used as an ultra-wide band tunable light source by switching a channel through which an injection current flows in the gain waveguide 17. Further, in the above configuration, if a wavelength multiplexed signal is made incident using the output waveguide 18 as an input waveguide and the gain in the gain waveguide 17 is not oscillated, it can be used as a duplexer.

[0015]

As described above , the wave according to the present invention is
Since the long multiplex light source uses an arrayed waveguide grating as a wavelength selection mechanism, it has the following effects. No crosstalk to other channels during operation. The number of channels can be increased. No coupling loss in principle and high coupling efficiency. Easy to make. A lossless duplexer can be configured. An ultra-wide band tunable light source can be configured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a wavelength division multiplexed light source according to one embodiment.

FIG. 2 is a diagram illustrating the demultiplexing characteristics of an arrayed waveguide grating.

FIG. 3 is a configuration diagram illustrating an example of a conventional wavelength multiplexed light source.

[Explanation of symbols]

 11A, 11B Semiconductor substrate for gain waveguide 12 Semiconductor substrate for passive waveguide 13A, 13B Fan-shaped slab waveguide 14A, 14B Focal plane 15A, 15B Arc plane 16 Array waveguide 17 Gain waveguide 18 Output waveguide 19 Corner for total reflection mirror

Claims (2)

(57) [Claims] 1. An arrayed waveguide comprising a plurality of waveguides having a delay time difference, and light beams from a plurality of waveguides of the arrayed waveguide provided at both ends of the arrayed waveguide are used as focal planes. A slab waveguide having a lens effect that converges to form an arrayed waveguide grating, and a plurality of gain waveguides are connected to the focal plane of one slab waveguide of the arrayed waveguide grating, An input / output waveguide is connected to the other slab waveguide, and a narrow band filter
Waves characterized by forming cavities with characteristics
Long multiplex light source. 2. A wavelength multiplexed light source according to claim 1, wherein the slab waveguide having a lens effect is constituted by a fan-shaped slab waveguide .