JPH0515360B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical Field of the Invention The present invention relates to an optical time division switch, and more particularly to an optical time division switch configured to reduce the number of optical switches while maintaining multiplicity. (b) Background of the Technology Some optical time division switches are constructed using an optical switch and a delay line. In order to increase the multiplicity of such an optical time division switch, the number of optical switches and delay lines must be increased. If so, the increase in these numbers must be kept as low as possible. (C) Prior Art and Problems An example of a conventional optical time division switch is an optical time division switch with a multiplicity of 4, that is, 4×4, as shown in FIGS. 1 and 2. In these figures,
a, b, c, d, e, and f are delay lines, and T shown within the delay line indicates one time slot time that is time-divided by the optical time division switch. S ₁ , S ₂ ,
S ₃ and S ₄ are two-input, two-output type optical switches. In order to generate the time division function as shown in FIG. 3 in the optical time division switch shown in FIG.
Switching as shown in Table 1 must be produced in each optical switch.

[Table] However, the = mark in Table 1 indicates that the switching method in the optical switch is as shown in Figure 4, and the × mark indicates that the switching method in the optical switch is as shown in Figure 5. . If an attempt is made to increase the multiplicity of such a type of optical time division switch, the number of optical switches will be 2N-4, where the multiplicity is N. Therefore,
As the degree of multiplicity increases, the number of optical switches increases at a rate approximately twice the degree of multiplicity, making it difficult to make optical time division switches. (d) Purpose of the Invention The present invention has been made in view of the drawbacks of conventional optical time division switches as described above, and its purpose is to reduce the number of optical switches by almost half when the multiplicity is kept the same. An object of the present invention is to provide an optical time division switch which can enjoy the ease of manufacturing of an optical time division switch. (E) Structure of the Invention In order to achieve this object, in an optical time division switch with multiplicity N, which is composed of a 2-input 2-output type optical switch and a delay line, a delay time of one time slot is added to the input light. is optically coupled to one input of an optical switch; one output of an optical switch preceding the optical switch is optically coupled to the input of the delay line; (N-1) optical switch stages of the same configuration are connected in cascade to optically couple the other output part of the previous stage optical switch to the other input part of the next stage optical switch, and the input of the first stage delay line is connected in series. is optically coupled to the input optical signal supply section, and optically closes the other input section of the first-stage optical switch, while the output section of the final-stage optical switch is connected to N via an optical OR circuit. It is configured as multiplexed time-division output. (F) Embodiments of the invention Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. FIG. 6 shows an embodiment of the invention. This embodiment shows an optical time division switch with a multiplicity of 4, that is, 4×4, and this optical time division switch 1 is an optical time division switch in which the output part of a delay line is optically coupled to one input part of the optical switch. It is constructed by cascading three stages of constituent elements as follows. The input section 4 ₁ of the delay line 3 ₁ of the first stage optical switch component 2 ₁ is coupled to an optical input data supply section that supplies an optical input data string that is time-multiplexed into four and outputted by the optical time division switch 1. This is the input section. The output 5 ₁ of the delay line 3 ₁ is optically coupled to one input 6 ₁ of the optical switch S ₁ . The other input section ₇₁ of the optical switch _S1 is optically closed. Since the manner of optical coupling of the optical switch components 2 ₂ and 2 ₃ from the second stage onward to the preceding stage is exactly the same,
The mode of optical coupling of the first-stage optical switch component 2 ₂ to the first-stage optical switch component 2 ₁ will be explained. That is, the optical coupling mode is such that the direct output section ₈₁ to one input section ₆₁ of the optical switch S1 of the _first stage optical switch component ₂₁ , which is the previous stage optical switch component, is connected to the next stage optical switch component. , for example _optically coupled to the input 4 2 of the delay line 3 ₂ of the second stage optical switch component _{2 2} , and the direct output 9 ₁ to the other input 7 ₁ of the optical switch S ₁ is an optical switch.
It is optically coupled to the other input ₇₂ of _S2 . The final stage, for example, the direct output section 8 ₃ of the optical switch S ₃
The output light from the direct output section 93 and the output light from the direct output section ₉₃ are outputted through an optical OR circuit (not shown). With this configuration, it is possible to perform the same functions as the 4×4 optical time division switch of the conventional configuration described above. For convenience of explanation, an example will be taken in which an output data string as shown in FIG. 3 is outputted via the optical time division switch 1 in response to an input data string as shown in FIG. For this purpose, each optical switch S ₁ , S ₂ , S ₃ of the optical time division switch 1 may be switched in the switching manner shown in Table 2.

[Table] However, as in Table 1, = and × in Table 2 indicate switching modes as shown in FIGS. 4 and 5. An example of the switching mode in Table 2 is as follows. For example _, in order to output data " ₂ " at time T ₂ of _the input data string in FIG _. Just switch it like in the ₀ column. Then, a multiplexed optical signal as shown in FIG. 3 is output from an optical OR circuit (not shown). The number of optical switches required to produce such switching can be increased by adding one stage of pairs of delay lines and optical switches as the multiplicity increases by one, so the multiplicity of the optical time division switch 1 can be increased by When N, it becomes (N-1). Therefore, according to the present invention, an optical time division switch can be constructed with approximately one-half the number of optical switches required to construct a conventional optical time division switch. Therefore, the optical time division switch can be made compact and easy to manufacture. In the above embodiment, the direct input section for one input section of the optical switch is connected to the input section of the next stage delay line, and the direct output section for the other input section is optically connected to the other input section of the next stage optical switch. The case where the deflection output section for one input section of the optical switch is connected to the input section of the next stage delay line, and the deflection output section for the other input section is connected to the other side of the next stage optical switch. It may be optically coupled to the input section, and the first and last stages may also take the same measures as described above. (G) Effects of the Invention As described above, according to the present invention, the number of optical switches required to configure an optical time division switch can be halved compared to the conventional one, thereby increasing the compactness of the optical time division switch. Effects such as being able to enjoy the advantages of manufacturing and ease of manufacture can be obtained.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing a conventional 4x4 optical time division switch, and Figure 3 is an input data string time-divided by the 4x4 optical time division switch and an output data sequence after time division. FIG. 4 and FIG. 5 are diagrams showing the switching mode of the optical switch, respectively.
FIG. 6 is a diagram showing an embodiment of the present invention. In the figure, 1 is an optical time division switch, 3 ₁ , 3 ₂ , 3 ₃
is a delay line, and S ₁ , S ₂ , and S ₃ are optical switches.

Claims (1)

[Scope of Claims] 1. In an optical time division switch with a multiplicity of N, which is composed of a 2-input 2-output type optical switch and a delay line, an output section of the delay line that gives input light a delay time of one time slot. is optically coupled to one input of an optical switch, one output of a preceding optical switch of the optical switch is optically coupled to an input of the delay line, and the other output of the preceding optical switch is optically coupled to an input of the delay line. (N-1) optical switch stages of the same configuration are connected in cascade, the output part of which is optically coupled to the other input part of the next optical switch, and the input part of the first stage delay line is connected to the input optical signal supply part. while optically coupling to the optical switch and optically blocking the other input section of the first-stage optical switch;
An optical time division switch characterized in that the output section of the optical switch at the final stage is N-multiplexed time division output via an optical OR circuit.