JPS5851248B2 - Optical wavelength selective coupling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical wavelength selective coupling device configured to provide an optical separation detection function, and in particular to a low-loss, high-density optical wavelength selective coupling device capable of detecting a large number of different wavelengths from a single optical waveguide. An object of the present invention is to obtain an optical wavelength selective coupling device having a function of selectively separating and receiving signals according to their wavelengths.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram for explaining the present invention, and shows one optical waveguide.

(However, in the figure, it is shown with a core indicated by number 1.

) and optical waveguide.

A plurality of N optical waveguides L1 are arranged adjacent to each other via a plurality of N (three in the figure) coupling portions C1, C2, . ．． L2...
In a configuration in which a coupling waveguide system is configured by LN, an optical waveguide.

and L12. L. and L2. ... A plurality of mutually different wavelengths λ1. between Lo and LN. The coupling portions C1 and C2 are connected so that reverse coupling is obtained for λ2...λN, respectively.
...CN has a plurality of N periodic structures F1. F2.・
...Has a configuration in which an FN is formed.

Note that the reverse directional coupling in this case is an optical waveguide.

and β0 and βN1 periodic structures F in which the phase constants of the guided modes propagating through Li (i=1,2...N) are different from each other.
When the period of i is 4i, the period Ai of the periodic structure Fi is selected so that the following relationship is satisfied.

However, in formula 1), K is an integer, usually 1.

Although the periodic structure Fi is known per se, it can be obtained by applying so-called uneven grading.

According to such a configuration, the length Li(
optical waveguide length (μm).

and the relationship between the coupling rate ηi of the reverse directional coupling between Li and the product Q i ′ of the length Li and the strength of periodic coupling Qi (degree of coupling per unit length of the periodic structure Fi)
The relationship of the coupling ηi with respect to Li is expressed as follows: The ratio Δ/Qi between Δ and the periodic coupling strength Qi given by Δ/Qi is used as a parameter, and the optical waveguide.

and the mode propagation loss α of Ll.

and the ratio of each of αi to Qi (α.

/Q, , αi/Qi) as shown in Fig. 2 as parameters, and the deviation of wavelength λ1 from the center wavelength △λ1
(A), coupling ratio ηi and transmittance Ti (optical waveguide).

is coupled to the optical waveguide L1, and the relationship is given by the transmittance through the position where the periodic structure Fi is arranged, respectively, using the length Li as a parameter.
As shown in the solid line and dotted line in the figure, the relationships between Li vs. η11 and Qi-Li vs. ηi in FIG.
By appropriately selecting the value of Li in advance from the relationships of Δλi vs. ηi and Δλi vs. Ti in the figure, the optical waveguide can now be constructed.

wavelength λ1. If we consider that light of wavelength λ2...λN is incident as shown by the solid line, then the light of wavelength λi can be led out through the optical waveguide Li as shown by the solid line, and an optical multiplexing function can be obtained. , and optical waveguide L1. L2
．． ...LN each have a wavelength λ1. If light of λ2...λN is made incident as shown by the dotted line, these will become an optical waveguide.

As shown by the dotted line, the light can be led out from one end of the light via the dotted line, thus providing an optical multiplexing function.

As described above, according to the configuration shown in FIG. 1, it is possible to obtain an optical demultiplexing or multiplexing function, and such a function is provided by an optical waveguide.

The bonding portion Ci is such that a reverse directional bond is obtained between Li and
Since it is obtained by a configuration in which a periodic structure Fi is formed in
These functions can be obtained with low loss, and the overall device can be constructed simply and with high density.

Also a waveguide. Since Li and Li have mutually different phase constants, high coupling efficiency can be obtained even for reverse coupling in the coupling portion C1.

Furthermore, since the periodic structure Fi formed in the coupling part Ci is based on uneven grading, it is possible to easily obtain a configuration in which reverse directional coupling can be obtained in the coupling part Ci.

Furthermore, by configuring the periodic structure Fi so that the condition Ql・Li≧3 is satisfied, the coupling rate of the opposite directional bond in the bonding portion C1 depends on the bond length, as is clear from FIG. It has unique characteristics such as being able to obtain a high constant value without doing much.

FIG. 4 shows an embodiment of the present invention, which has a structure in which a cladding layer 2, a core layer 1, a cladding layer 2', a core layer 1', and a cladding layer 2'' are laminated in that order. An optical waveguide is formed by the cladding layer 2', the core layer 1' and the cladding layer 2'.

The cladding layer 2', the core layer 1, and the cladding layer 2 form a coupling part C8 in the cladding layer τ, and two coupling waveguide systems are arranged in parallel with each other via the coupling part C6. In the configuration, - a plurality of N mutually different wavelengths λ1 . Periodic structures F1°F2...FN for λ2...λN are sequentially formed at predetermined intervals at positions in contact with the core layer 1, and, for example, in the cladding layer 2 on the / side of the optical waveguide L. Periodic structure F1. F2・
. . . A plurality of N photodetectors D1 corresponding to FN. D2...
- It has a structure in which DNs are sequentially arranged at predetermined intervals at positions in contact with the core layer 1.

The above is the configuration of the embodiment of the present invention. According to such a configuration, substantially the same function as the configuration shown in FIG. 1, that is, an optical multiplexing function can be obtained.

Therefore, it is an optical waveguide. From one end of the wavelength λ1゜λ2...
If light having wavelength λN is incident, these wavelengths λ1.
Lights having wavelengths λ2...λN are detected by optical detectors DI, D2, and λN, respectively.
...Injects into the DN and is completely absorbed by the detector.

Therefore, from the terminal Yi derived from the photodetector Di, the wavelength λi
Detection output of light having .

The waveguide used in the present invention has the configuration shown in FIG.
However, all of the demultiplexed λ1 light is absorbed by the photodetector, so although the Di and Fl-1 parts are connected by a waveguide, they are functionally separated. 1. Therefore, an optical wavelength selective coupling device is obtained which has the same effect as that shown in FIG. 1 and also has a photodetection function.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view for explaining the function of the optical wavelength selective coupling device according to the present invention, and FIG. 2 is a line diagram for explaining the function.
A curve diagram showing the relationship between i vs. ηi and Qi-LiMηi, FIG. 3 is a curve diagram showing the similar relationship between Δλi vs. η11 and Δλi vs. Ti, and FIG. FIG. 2 is a cross-sectional view showing an embodiment of an optical wavelength selective coupling device configured to perform the following steps. In the figure, Lo and Li are optical waveguides, co and C1 are coupling parts, and F
i is a periodic structure, Di is a photodetector, ¥1 is a terminal, and 1 is a core layer. 2′ and 2″ are cladding layers.

Claims (1)

[Claims] Twelve optical waveguides. Andri. In the coupled waveguide system in which the optical waveguides 1 and 2 are arranged in close proximity to each other via the coupling portion CO, Andri. ' have mutually different phase constants, and a plurality of N mutually different wavelengths λ1 . Periodic structure Fl t F by unevenness grading for λ2...λN
2...FN is the periodic bond strength Q of the periodic structure Fi
i (where i=1°2...N) and length Li are Qi-L
The optical waveguides are sequentially formed at predetermined intervals so as to satisfy the i2S condition. Andri. The above periodic structure Fl ? F2...
- A plurality of N photodetectors D1 corresponding to FN. D2...
An optical wavelength selective coupling device characterized in that a DN is provided so that an optical separation detection function can be obtained.