JP3196785B2 - Waveguide type laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention TECHNICAL FIELD OF THE INVENTION is concerned primarily waveguide laser that will be used in optical communication components field.

[0002]

2. Description of the Related Art In optical communication, multiplexing the wavelength of signal light propagating in an optical fiber is one of effective methods for increasing the transmission information density. In the wavelength multiplexing method, a large number of semiconductor lasers (L
D) is required. In addition, for high-density multiplex wavelength multiplexing / demultiplexing, it is desirable that the wavelengths of the LDs are equally spaced and that the wavelength spacing is narrow. Until now, a narrow band distributed feedback semiconductor laser (DFB-LD) has been developed for use in wavelength multiplexing by controlling the wavelength by controlling the temperature and current.

[0003]

However, the above D
In the FB-LD, it has been difficult to control the wavelength at narrow equal intervals because of problems such as stability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an arrayed waveguide type diffraction grating comprising an optical waveguide for a wavelength multiplexing system.
An object of the present invention is to provide a stable multi-wavelength oscillation laser at equal intervals by combining an amplification medium such as D.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0006]

In order to achieve the above object, the means (1) of the present invention comprises a plurality of input waveguides.
If, possess an input and an output, said plurality of said input end
A two-dimensional waveguide input waveguide is connected, the two-dimensional waveguide is a connected to the output terminal, the three-dimensional waveguide of each length is different multiple <br/> number, the plurality of three-dimensional Said waveguide 2
A high-reflectance termination installed on the side not connected to the two-dimensional waveguide; and a two-dimensional waveguide of the plurality of input waveguides.
An amplification medium which is provided on a side that is not connected, the amplifier
An output module installed on the opposite side of the medium to the two-dimensional waveguide.
And a puller .

The means (2) of the present invention comprises an input terminal and an output terminal.
First and second two-dimensional waveguide, the <br/> first 2-dimensional waveguide output end and the second two-dimensional waveguide and a power end
Connected to the input end of each
Wherein a dimension waveguides, an input end of said first two-dimensional waveguide
It has at least one amplifying medium connecting the output end of the second two-dimensional waveguide, and a directional coupler for extracting laser oscillation light .

Further, a semiconductor amplifier is used as the amplification medium.

[0009] The present invention is characterized in that an Er- doped optical fiber is used as the amplifying medium.

[0010]

According to the above means, the oscillation wavelengths of a large number of lasers are controlled by a single array waveguide type diffraction grating.
A multi-wavelength laser whose wavelength interval is controlled stably and with high precision can be manufactured.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[0012] First, a description will be given of the basic structure of all of the embodiments of the waveguide laser of the present invention.

[0013] Figure 1 is a schematic diagram for explaining the basic structure of all of the embodiments of the waveguide laser of the present invention, 1 is a silicon (Si) substrate, 2 is a three-dimensional waveguide incident, Reference numeral 3 denotes a two-dimensional waveguide, reference numerals 4 and 5 denote three-dimensional waveguides, reference numerals 6 and 7 denote high-reflectance termination portions, reference numeral 8 denotes an array of amplification media, reference numeral 9 denotes a dielectric multilayer mirror, and reference numeral 10 denotes a Rowland circle.

First, the function of the arrayed waveguide type diffraction grating will be described with reference to FIG.

The array waveguide type diffraction grating used in the present invention is composed of a plurality of three-dimensional waveguides 4 and 5 having different lengths.
By making the phase of light different between the three-dimensional waveguides 4 and 5, the three-dimensional waveguides 4 and 5 are not restricted in shape.
High resolution is realized by causing a large path length difference between them.
Theoretically, if the path length difference between the adjacent three-dimensional waveguides 4 and 5 is ΔL / 2, the light enters from the three-dimensional waveguide for incidence 2 and enters the two-dimensional waveguide 3 and the three-dimensional waveguides 4 and 5. The diffraction angle β of the diffracted light in the two-dimensional waveguide 3 of the light reflected and returned through is given by the following equation.

[0016]

D (sinα + sinβ) n + ΔLn = mλ (1) where d is a distance between the plurality of three-dimensional waveguides 4 and 5 in a portion coupled to the two-dimensional waveguide 3, α is an incident angle, n is a refractive index and m is an integer. In the vicinity of the incident angle of 0 and the diffraction angle of 0, the relationship between the light condensing position x and the wavelength λ is given by the following equation.

[0017]

## EQU2 ## dx / dλ = fm / nd (2)

[0018]

M = ΔLn / λ (3) where f is the radius of curvature of the two-dimensional waveguide 3 and corresponds to the focal length. Since the array waveguide type diffraction grating has no limit to ΔL, high resolution can be easily achieved.

As described above, only a specific wavelength is diffracted into the incident three-dimensional waveguide 2. Accordingly, a specific wavelength is diffracted by each amplification medium of the array 8 of the amplification medium connected to each of the three-dimensional waveguides 2 for incidence, and each amplification medium oscillates at a different wavelength. In the array waveguide type diffraction grating, the wavelengths of the light diffracted by the three-dimensional waveguide for incidence 2 are at equal intervals, so that the laser oscillation wavelengths of the respective amplification media can be equal.

[Embodiment 1] In this embodiment 1, an arrayed waveguide type diffraction grating was made of a silica glass optical waveguide, and a 1.55 μm band semiconductor amplifier was connected as an amplification medium.

[0021] Figure 2 is a schematic diagram for explaining a schematic configuration of a waveguide laser of the first embodiment of the present invention, 1a is a silicon substrate, 2a is a three-dimensional waveguide incident made of silica based glass, 3a is a two-dimensional waveguide made of quartz glass, 4
a and 5a are three-dimensional waveguides made of silica glass, 10a
Is a Roland circle, 11 is a total reflection mirror, and 12 is a semiconductor amplifier.

A quartz optical waveguide having an arrayed waveguide type diffraction grating was manufactured by flame deposition (FHD) and reactive ion etching (RIE).

The manufacturing procedure of the first embodiment will be described below.

A lower clad and a core are formed on the silicon substrate 1a by the FHD method.

The waveguide core pattern having the structure shown in FIG. 1 is transferred by photolithography, and a core is formed by RIE.

An upper clad is deposited by the FDH method to produce a buried waveguide.

The cores of the manufactured three-dimensional waveguides 2a, 4a, 5a were 6.5 × 6.5 μm, and the difference in non-refractive index between the core and the clad was 0.75%. The wavelength interval of light diffracted into the three-dimensional waveguide for incidence 2a of the arrayed waveguide type diffraction grating is set to 1
The two-dimensional waveguide 3a and the three-dimensional waveguides 4a and 5a were designed to be 0 GHz.

After the fabrication of the waveguide, the total reflection mirror 11 was bonded. Further, in the semiconductor amplifier 12, a non-reflective dielectric multilayer film is provided on the end face connected to the waveguide so that reflection does not occur, and a reflectivity of about 90 in a 1.55 μm band is provided on the end face on the emission side.
% Of output multilayer mirrors were deposited.

Regarding the manufactured laser, the semiconductor amplifier 12
The characteristics were examined by passing a current through the device. Three semiconductor amplifiers 12
When a current of 50 mA is applied to each of the semiconductor amplifiers 12, the semiconductor amplifiers 12 oscillate at different wavelengths, and the wavelength interval is 1
It was 0 GHz.

The effectiveness of the present invention has been confirmed from the results of the present embodiment.

[Second Embodiment] In the second embodiment, an Er-doped optical fiber is used as an amplifying medium instead of the semiconductor amplifier used in the first embodiment.

FIG. 3 is a schematic view for explaining a schematic configuration of the laser according to the second embodiment of the present invention, wherein 1b is a silicon substrate, 3b is a two-dimensional waveguide, 4b and 5b are three-dimensional waveguides, 10b is a Rowland circle, 11a is a total reflection mirror, 1
3, 13a are Er-doped optical fibers, 14, 14a are Er.
LD for pump consisting of doped optical fiber (wavelength 1.47μ)
m), 15 and 15a are optical directional couplers for introducing pump light,
Reference numeral 16 denotes an optical fiber array mounting component, and reference numeral 17 denotes an optical fiber array with a dielectric multilayer mirror for extracting laser oscillation light.

An arrayed waveguide type diffraction grating was formed on a silicon substrate 1b in the same manner as in Example 1. The diffraction grating was designed so that the diffraction interval between the three-dimensional waveguides 4b and 5b was 20 GHz. With respect to the manufactured laser, the output of each Er pumping LD was incident on each of the Er-doped optical fibers 13 and 13a via a directional coupler, and the laser oscillation characteristics were examined. Er
Output 1.47 μm wavelength 30 to the added optical fibers 13 and 13a.
If the incident pump light of mW, dielectric multi-layer film mirror
Fiber array 17 equipped with an output coupler
As a result, a laser output was obtained for each optical fiber. Laser light from each optical fiber oscillated separately at intervals of 20 GHz in accordance with the wavelength interval of the arrayed waveguide grating.

Embodiment 3 In Embodiment 3, a ring resonator type laser was formed using an arrayed waveguide type diffraction grating.

FIG. 4 is a view for explaining a schematic configuration of a ring resonator type laser using the arrayed waveguide type diffraction grating according to the third embodiment of the present invention.
c and 3d are two-dimensional waveguides, 10c and 10d are Roland circles, 13b and 13c are Er-doped optical fibers, 14b and 1
4c is a pump LD composed of an Er-doped optical fiber, 15
Reference numerals b and 15c denote optical directional couplers for introducing pump light, 18 denotes an array three-dimensional waveguide, and 19 and 19a denote directional couplers for extracting laser oscillation light.

An arrayed waveguide type diffraction grating fabricated on a silicon substrate 1c was fabricated in the same manner as in Example 1. The size of the core of the fabricated waveguide was 6.5 × 6.5 μm, and the difference in non-refractive index between the core and the clad was 0.75%. The wavelength interval of the light diffracted into the incident three-dimensional waveguides 2c and 2d of the arrayed waveguide type diffraction grating was set to 10 GHz. Er-doped optical fibers 13b and 13c are provided on both end surfaces of the manufactured diffraction grating.
Were connected to form a ring resonator structure. In this case, the diffraction wavelengths of the incident three-dimensional waveguides 2c and 2d for connecting the optical fibers are set to be the same. Er-doped optical fiber 13
The length of each of b and 13c was 20 m. LD has a wavelength of 1.4
7 μm.

With respect to the produced laser, each Er excitation L
The output of D was incident on each of the Er-doped optical fibers 13b and 13c via the directional coupler, and the laser oscillation characteristics were examined. A current of 50 mA was passed through each of the pump LDs, and 30 mW of pump light was incident on the Er-doped optical fibers 13b and 13c. As a result, laser beams oscillating at different wavelengths were obtained from the directional couplers for extracting laser output attached to the Er-doped optical fibers 13b and 13c. The wavelength interval is 10
At GHz, the half width of the laser spectrum was 0.1 nm.

The effectiveness of the present invention was confirmed from the results of Examples 1, 2 and 3 described above.

In the first, second, and third embodiments, the Er-doped optical fiber is used as the amplifying medium.
A D array and an optical fiber array can also be used.

In addition to the embodiments described above, other rare earth-doped optical fibers can be used as the amplification medium. It is also possible to construct a monolithic laser by forming an arrayed waveguide type diffraction grating using a rare-earth-doped quartz glass waveguide.

As described above, the present invention has been specifically described based on the embodiments. However, it is needless to say that the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention. Absent.

[0042]

As described above, according to the present invention, since the oscillation wavelengths of a large number of lasers are controlled by a single array waveguide type diffraction grating, the wavelength interval can be controlled stably and with high precision. Multi-wavelength lasers can be made.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a basic structure of all embodiments of a waveguide laser according to the present invention;

FIG. 2 is a schematic diagram illustrating a schematic configuration of a waveguide laser according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram for explaining a schematic configuration of a laser according to a second embodiment of the present invention.

FIG. 4 is a diagram for explaining a schematic configuration of a ring resonator type laser using an arrayed waveguide type diffraction grating according to a third embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1b, 1c: silicon (Si) substrate, 2, 2
a, 2b, 2c, 2d ... three-dimensional waveguide for incidence, 3, 3
a, 3b, 3c, 3d ... two-dimensional waveguide, 4, 4a, 4b
... three-dimensional waveguide, 5, 5a, 5b ... three-dimensional waveguide, 6 ...
High reflectivity termination, 7: High reflectance termination, 8: Array of amplification media, 9: Dielectric multilayer mirror, 10, 10a, 10
b: Roland circle, 11, 11a: Total reflection mirror, 12
... Semiconductor amplifiers, 13, 13a, 13b, 13c ... Er
Doped optical fiber, 14, 14a ... LD for pump, 15,
15a, 15b, 15c: optical directional coupler for introducing pump light, 16: optical fiber array mounting component, 17: optical fiber array with dielectric multilayer mirror for extracting laser oscillation light, 18: array three-dimensional waveguide, 19 , 19a: Directional coupler for extracting laser oscillation light.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Hida 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Jingu-ji Kaname 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan Nippon Telegraph and Telephone Corporation (72) Inventor Ota Suzuki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Yasuyuki Inoue 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph JP-A-5-198893 (JP, A) JP-A-62-29891 (JP, A) JP-A-2-244105 (JP, A) JP-A-4-99080 (JP) , A) JP-A-4-75036 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 H01S 3/00-3/30

Claims (4)

(57) [Claims] And 1. A plurality of input waveguides, possess an input and an output, said plurality of input to the input terminal
A two-dimensional waveguide Yoshirube waveguides are connected, is connected to the output terminal of the 2-dimensional waveguide, each length
Is connected and a plurality of 3-dimensional waveguides different in the 2-dimensional waveguide of the plurality of three-dimensional waveguide
And high reflectance termination which is provided on a side not being connected to the 2-dimensional waveguide of the plurality of input waveguides
An amplification medium which is provided on a side not, is placed on the opposite side of the 2-dimensional waveguide of the amplification medium
Waveguide laser it characterized by an output coupler that. 2. A first and a second circuit, each having an input and an output.
Beauty and second two-dimensional waveguide, the first two-dimensional waveguides connecting the output end and the input end of said second two-dimensional waveguides, a plurality of three-dimensional waveguide path different lengths each And an input end of the first two-dimensional waveguide and the second two-dimensional waveguide.
At least one amplification medium and, waveguide laser you; and a laser oscillation light extraction directional coupler connecting the waveguide outputs. As claimed in claim 3, wherein the amplifying medium, guiding <br/> waveguide type laser according to claim 1 or claim 2, characterized by using a semiconductor amplifier. Wherein as said amplifying medium, waveguide laser of claim 1 or claim 2, characterized by using the Er-doped optical fiber.