JP2723586B2 - Optical wavelength separation circuit and optical wavelength multiplexing circuit - Google Patents

Description

The present invention relates to an optical wavelength separation circuit for separating signal light of each wavelength from a narrow signal light having a multiplex wavelength interval of at least 10 nm or less, and a signal light having a narrow multiplex wavelength interval. The present invention relates to an optical wavelength multiplexing circuit for multiplexing.

(Prior Art) As shown in FIG. 2, a conventional wavelength separation multiplexing circuit maintains an input angle of signal light to an interference filter 1 at a large angle of about 20 ° to 45 °, and transmits and reflected waves. Or multiplex transmitted and reflected waves.

(Problems to be Solved by the Invention) In the conventional technology, multiple wavelength intervals are, for example, 1.3 μm and 1.5 μm.
It can be applied to signal light that is separated by several hundred nm or more, such as m.

However, signal light having a multiplex wavelength interval of about 10 nm or less cannot be separated by this method. This is because, as the incident angle θ increases, the steep cutoff characteristic of the interference film filter, that is, the narrow band pass characteristic is not preserved. This is because the reflectivity of the p-wave and the s-wave included in the signal light becomes different as θ increases. Although θ is 0, that is, at normal incidence, even though an interference film filter having a narrow band pass band of sub-nm has already been realized, it is returned on the same optical axis as the incident light. Has a problem that the narrow band property cannot be sufficiently exhibited.

Therefore, in the conventional configuration, it is difficult to separate the signal light of each wavelength from the signal light having a narrow multiplex wavelength interval. For the same reason, multiplexing is also difficult.

(Object of the Invention) An object of the present invention is to provide an optical wavelength separation circuit for separating each wavelength from a narrow signal light having a multiplex wavelength interval of at least 10 nm or less using an interference film filter, and a light multiplexed into a signal light having a narrow multiplex wavelength interval. A wavelength multiplexing circuit is provided.

(Means for Solving the Problems) In order to achieve the above object, according to the invention of claim 1, an N-port optical circulator having a plurality of ports 1 to N, and N-port optical circulators other than port 1 and port N are provided. A narrow-band interference filter provided at each of the two ports and having a different pass-band characteristic from each other; a signal light wavelength-multiplexed from port 1 is input; The signal light was vertically incident on the membrane filter, and the wavelength-separated signal light was output. At the port N, the remaining signal light was output.

According to the second aspect of the present invention, an N-port optical circulator having a plurality of ports from port 1 to port N and a wide band provided in each of N-1 ports other than port 1 and having different pass band characteristics from each other. An interference film filter is provided so that the wavelength division multiplexed signal light is input from port 1 and the signal light is vertically incident on the broadband interference film filter at each of the other ports so as to output wavelength-separated signal light. And an N-port optical circulator having a plurality of ports, port 1 to port N, and N-2 ports other than port 1 and port N, respectively. A narrow-band interference film filter having a different band characteristic; a wavelength-multiplexed signal light is input from port 1; The signal light is vertically incident on the thin film filter to output a wavelength-separated signal light, and the port N outputs the remaining signal light. Ports 1 of a plurality of subsequent optical wavelength demultiplexing circuits were optically coupled to ports other than port 1 of the circuit.

According to the third aspect of the present invention, an N-port optical circulator having a plurality of ports from port 1 to port N, and N-2 ports other than port 1 and port N provided in each of the two pass-band characteristics. Are different from each other in a narrow-band interference filter. Ports other than port 1 and port N input signal light to be wavelength-division multiplexed to the narrow-band interference filter vertically, and port N receives signal light to be wavelength-multiplexed. Output the wavelength-multiplexed signal light.

Further, according to the invention of claim 4, an N-port optical circulator having a plurality of ports from port 1 to port N and N-2 ports other than port 1 and port N are provided in each of the passband characteristics of each other. Are different from each other in a narrow-band interference filter. Ports other than port 1 and port N input signal light to be wavelength-division multiplexed to the narrow-band interference filter vertically, and port N receives signal light to be wavelength-multiplexed. , An N-port optical circulator having a plurality of ports from port 1 to port N, and N-1 ports other than port 1. And a broadband interference filter having a different pass band characteristic from each other. A post-stage optical wavelength multiplexing circuit for inputting light vertically to the broadband interference filter and outputting wavelength-multiplexed signal light from port 1; Ports 1 of a plurality of optical wavelength multiplexing circuits at the preceding stage were optically coupled.

(Operation) According to claims 1 and 2, the wavelength-division multiplexed signal light input from the port 1 is propagated from the port 2 to the port N by the optical circulator, and is vertically transmitted to the interference filter provided in each port. Only the signal light having a wavelength within the pass band of the filter that is incident is output and separated, and the signal light of another wavelength is vertically reflected and propagated to the next port to be separated.

According to the third and fourth aspects, the signal light for multiplexing input from each port is propagated by the optical circulator, multiplexed while being vertically reflected by the interference filter after the next port, and output from the port 1. You.

(Embodiment) FIG. 1 shows a first embodiment of an optical wavelength demultiplexing circuit according to the present invention. In the drawing, reference numeral 2 denotes a known clockwise optical circulator, which has an input port (P1) and a right-hand port. It has four ports of port 2 (P2), port 3 (P3), and port 4 (P4) on the output side arranged in a circumferential direction. Reference numeral 7 denotes an interference film filter having a pass band of sub-nm, which passes only the wavelength λ1, and is provided at the port P2. Reference numeral 8 denotes an interference film filter having a sub-nm pass band that transmits only the wavelength λ2, and is provided at the port P3. The loss characteristics of the interference film filter are as shown in FIG.

In the above-described configuration, when three-wavelength multiplexed signal light having the wavelengths λ1, λ2, and λ3 is input from the port P1, it is propagated to the port P2 by the operation of the optical circulator 2. Here, only the signal light of the wavelength λ1 is output from the port P2 which is transmitted and separated by the interference filter 7. The other two wavelengths are reflected by the interference filter 7. The reflected signal light is propagated to the port P3 according to the operation of the optical circulator 2. Here, only the signal light of wavelength λ2 is transmitted and separated by the interference film filter 8 and output. The signal light having the wavelength λ3 is reflected by the interference film filter 7, propagates to the port P4, and is output from the port P4. In this way, wavelength separation is realized.

FIG. 4 shows a first embodiment of the optical wavelength multiplexing circuit according to the present invention. In the figure, reference numeral 3 denotes a known counterclockwise optical circulator, which is connected to an output port 1 (P1) and a clockwise direction from the port 1 (P1). It has four ports, input port 2 (P2), port 3 (P3), and port 4 (P4) on the input side. 7 is the wavelength λ1
With a pass band sub-nm interference film filter that transmits only
Provided on port P2. Reference numeral 8 denotes an interference film filter having a sub-nm pass band that transmits only the wavelength λ2, and is provided at the port P3.

In the above-described configuration, the signal lights of the wavelengths λ1, λ2, λ3 input from the ports P4 to P2 are propagated counterclockwise by the operation of the optical circulator 3, and the interference film filters 7,
After repeating the reflection by 8, the signals are multiplexed and output from the port P1.

FIG. 5 shows a second embodiment of the optical wavelength demultiplexing circuit according to the present invention, in which nine multiplexed signal lights having wavelengths λ1 to λ9 are separated into respective signal lights. That is, reference numerals 4, 5, and 6 denote clockwise optical circulators each having four ports P1 to P4, similarly to the clockwise optical circulator 2 of the first embodiment shown in FIG. 7, only wavelength λ1, 8 only wavelength λ2, 9 only wavelength λ4, 10 only wavelength 5,
Reference numeral 11 denotes an interference film filter having a pass band of sub-nm which transmits only the wavelength λ7, and reference numeral 12 denotes an interference film filter provided in the corresponding output port. 13 is the wavelength λ1 to λ3
Reference numeral 14 denotes a broadband interference filter transmitting the wavelengths λ4 to λ6, and reference numeral 15 denotes a broadband interference film filter which transmits the wavelengths λ7 to λ9, provided at the ports P2 to P4 on the output side of the optical circulator 2. The input ports P1 of the optical circulators 4 to 6 are optically coupled to the output ports P2 to P4 of the optical circulator 2 via the interference film filters 13 to 15, respectively.

In the above-described configuration, when nine-wavelength multiplexed signal light of wavelengths λ1 to λ9 is input from the port P1 of the optical circulator 2 in the preceding stage, the ports P2 to P4 on the output side of the optical circulator 2 are operated in the same manner as described above. , Are propagated to the optical circulators 4 to 6 at the subsequent stages, respectively.
In each of the optical circulators 4 to 6, the signals of λ1 to λ9 are separated and output from the ports P2 to P4 on the output side by the same operation as described above.

FIG. 6 shows a second embodiment of the optical wavelength multiplexing circuit according to the present invention. The clockwise optical circulators 2 and 4 to 6 shown in FIG. 5 are replaced with the clockwise optical circulators 3 and 16 to 18. The interference membrane filters 19 to 24 are replaced with the interference membrane filters 7 to 12 shown in FIG.
Has the same configuration as the interference film filters 13 to 15 in FIG.

According to the above configuration, each of the optical circulators 16 to
When the signal light of each wavelength λ1 to λ9 to be multiplexed is input from each of the input ports P2 to P4 of the 18, the signal light multiplexed by the three waves in each of the optical circulators 16 to 18 by the reverse operation of the separation is output to the subsequent stage. Of each input side of the optical circulator 3
The signal is input from P4 to the optical circulator 3, where it is further multiplexed into nine waves by the same operation as described above and output from the port P1.

(Effect of the Invention) As described above, according to the first and third aspects of the present invention, since the optical circulator is used, normal incidence on the interference film filter is possible, so that the interference film has a narrow band pass characteristic. The characteristics of the filter can be sufficiently brought out. Therefore, N-wave signal light multiplexed at sub-nm intervals can be separated for each wavelength or N-multiplexed at sub-nm intervals. According to the inventions of claims 2 and 4, in addition to the effects of the inventions of claims 1 and 3, there is an advantage that the number of wavelengths that can be separated or multiplexed can be increased as necessary.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical wavelength separation circuit according to a first embodiment of the present invention, FIG. 2 is a schematic diagram of a conventional wavelength separation multiplexing circuit, and FIG. 3 is a loss of a sub-nm interference film filter realized. FIG. 4 is a diagram showing an optical wavelength division multiplexing circuit according to a first embodiment of the present invention, FIG. 5 is a diagram showing a second embodiment of the optical wavelength demultiplexing circuit of the present invention, and FIG. FIG. 5 is a diagram illustrating an optical wavelength multiplexing circuit according to a second embodiment of the present invention. 2,4,5,6 …… clockwise optical circulator, 3,16,17,18 ……
Counterclockwise optical circulator, 7, 8, 9, 10, 11, 12, 19, 20, 21, 2
2,23,24 …… Sub-nm interference filter, 13,14,14,25,27,
28 …… Broadband interference filter.

Claims (4)

(57) [Claims] An N-port optical circulator having a plurality of ports from port 1 to port N, and a narrow band provided in each of N-2 ports other than port 1 and port N and having different pass band characteristics from each other. A signal light wavelength-division multiplexed from port 1 and input to the narrow-band interference film filter at each of the other ports except port N. And the port N outputs the remaining signal light. 2. An N-port optical circulator having a plurality of ports from port 1 to port N;
A broadband interference filter provided in each of the one ports and having different passband characteristics from each other;
Each of the other ports is provided with a pre-stage optical wavelength separation circuit configured to input the wavelength-multiplexed signal light and output the wavelength-separated signal light by vertically inputting the signal light to the broadband interference film filter at each of the other ports. And an N-port optical circulator having a plurality of ports from port 1 to port N;
A narrow-band interference filter provided in each of the two ports and having different pass-band characteristics from each other;
In each of the other ports except port N, the signal light is vertically incident on the narrow-band interference filter, and wavelength-separated signal light is output from each port except port N. Port N outputs the remaining signal. A plurality of optical wavelength demultiplexing circuits at the subsequent stage configured to output light are provided, and ports 1 of the optical wavelength demultiplexing circuits at the subsequent stage are optically coupled to respective ports other than the port 1 of the optical wavelength demultiplexing circuit at the preceding stage. Optical wavelength separation circuit. 3. An N-port optical circulator having a plurality of ports from port 1 to port N, and narrow-band interference provided in each of N-2 ports other than port 1 and port N and having different pass band characteristics from each other. In the ports other than port 1 and port N, signal light to be wavelength-multiplexed is input vertically to the narrow-band interference filter, and signal light to be wavelength-multiplexed is input to port N and wavelength-multiplexed from port 1. An optical wavelength multiplexing circuit for outputting a signal light. 4. An N-port optical circulator having a plurality of ports from port 1 to port N, and a narrow band provided in each of N-2 ports other than port 1 and port N and having different pass band characteristics from each other. In the ports other than port 1 and port N, signal light to be wavelength-multiplexed is input vertically to the narrow-band interference filter, and signal light to be wavelength-multiplexed is input to port N, and wavelength-multiplexed from port 1. N-port optical circulator having a plurality of ports of port 1 to port N and a plurality of N-1 ports other than port 1 in addition to a plurality of optical wavelength multiplexing circuits at the preceding stage configured to output And a broadband interference film filter having different passband characteristics from each other. The optical wavelength multiplexing circuit of the subsequent stage is provided so as to be input vertically to the bandpass interference film filter and to output the wavelength-multiplexed signal light from the port 1. An optical wavelength multiplexing circuit, wherein ports 1 of a plurality of optical wavelength multiplexing circuits are optically coupled.