JP2965620B2 - Time division type optical pulse multiplexing / demultiplexing circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an all-optical time-division optical pulse that multiplexes or separates a modulated signal optical pulse train on a time axis using a control optical pulse. It relates to a multiplexing / demultiplexing circuit.

[Prior art] Conventionally, there has been an all-optical car switch using the optical Kerr effect as a time division type optical pulse multiplexing / demultiplexing circuit, and it is promising as a high-speed optical pulse multiplexing / demultiplexing circuit having a band of about several THz. Have been. FIG. 4 shows a configuration diagram of a conventional optical pulse separation circuit using the optical Kerr effect. When the multiplexed signal light pulse train A having a bit rate of 2f ₀ b / s and the control gate light pulse train B having a repetition f ₀ b / s pass through the optical Kerr medium 2 via the multiplexing mirror 1, time The polarization state changes only in every other signal light pulse train that overlaps on the axis, and can be separated into two signal light pulse trains C and D of repetition f ₀ b / s by the polarization beam splitter 3.

[Problem to be Solved by the Invention] However, in this case, the polarization of the signal light and the polarization of the control light
It was necessary to obtain linearly polarized light, and the polarization dependence could not be excluded.

The present invention realizes an all-optical switch which does not depend on the polarization state of signal light, and has an object to stabilize an ultrafast signal light pulse of any polarization state used in an optical fiber communication system. Another object of the present invention is to provide a high-speed time-division demultiplexing circuit.

[Means for Solving the Problems] An optical pulse separation circuit according to the present invention comprises: an optical circulator operating at a wavelength of a signal light; And an optical coupler having two input arms and two output arms that splits signal light into two output arms 1: 1 and guides control light 100% to one output arm. An optical pulse separation circuit comprising: an optical Kerr medium having an optical Kerr medium; and optical demultiplexing means for demultiplexing signal light having an arbitrary polarization state and control light having a circular polarization. At one end of the Kerr medium, another output arm is connected to the other end of the Kerr medium. The optical circulator, the optical multiplexing means, the optical coupler, and the optical demultiplexing means are arranged in this order. Is connected to the terminal.

An optical pulse multiplexing circuit according to the present invention includes: an optical multiplexing unit that multiplexes a signal light having an arbitrary polarization state and a control light having a circular polarization; a signal light that is separated into two output arms by 1: 1; , An optical coupler having two input arms and two output arms for guiding 100% to one output arm, an optical Kerr medium having an optical Kerr effect, signal light having an arbitrary polarization state, and control light having a circular polarization. An optical pulse multiplexing circuit comprising: an optical demultiplexing means for demultiplexing the optical signal; and an optical circulator operating at the wavelength of the signal light, wherein one output arm of the optical coupler is provided at one end of the optical Kerr medium, Another output arm is connected to the other end of the optical Kerr medium, and the optical multiplexing means, the optical coupler, the optical demultiplexing means, and the optical circulator are connected in this order. I do.

[Operation] The present invention uses an optical circulator, an optical multiplexer, an optical coupler, an optical Kerr medium, and an optical demultiplexer that operate on circularly polarized control light and arbitrary polarized signal light using circularly polarized control light. The use of a device performs ultra-high-speed time-division multiplexing / demultiplexing.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

First, FIG. 3 illustrates the phase induced by the control light of the circularly polarized light used in the ring type optical demultiplexing circuit of the present invention. As shown in FIG. 3 (a), when the control light is circularly polarized, the power of the control light parallel to the polarization of the signal light and the control light perpendicular to the polarization of the signal light for an arbitrary polarization state of the signal light. Power is always equal. Therefore, the same phase change is induced as shown in FIG. 3 (b), and its polarization dependence is eliminated. Therefore, if circularly polarized control light is used for the ring type optical switch, an optical switch having no polarization dependence of the input signal can be configured.

(1) Ring type light separating circuit FIG. 1 shows an example of a ring type light separating circuit. In FIG. 1, reference numeral 11 denotes an optical circulator (CIR), reference numeral 12 denotes an input port thereof, reference numerals 13 and 14 denote output ports, reference numeral 15 denotes an optical multiplexer (WF1; optical multiplexing means), and reference numerals 16 and 17 denote inputs thereof. Port, reference numeral 18 is an output port, reference numeral 19 is an optical coupler (CO), reference numerals 20 and 21 are input arms thereof, reference numerals 22 and 23 are output arms,
Reference numeral 24 denotes an optical Kerr medium (KM), reference numeral 25 denotes an optical demultiplexer (WF2; optical demultiplexing means), reference numeral 26 denotes an input port thereof, and reference numerals 27 and 28 denote output ports.

The signal light of any polarization input from the input port 12 of the optical circulator 11 is output from the output port 13, is multiplexed with the control light having circular polarization by the optical multiplexer 15, and is input to the input arm 20 of the optical coupler 19. Be guided. In the optical coupler 19, the signal light is 1: 1
The control light is guided to the output arms 22 and 23, respectively, and the control light is guided 100% to one of the output arms. The output arms 22 and 23 of the optical coupler 19 are coupled to both ends of the Kerr medium 24. The other input arm 21 of the optical coupler 19 is an optical demultiplexer.
The control light is output from an output port 28 and the signal light is output from an output port 27.

In this case, since the output arms 22 and 23 of the optical coupler 19 are connected to both ends of the optical Kerr medium 24, the control light input to the optical coupler 19 transmits the signal light in one direction around the optical Kerr medium 24. Propagates in both directions. At this time, the signal light traveling in the same direction as the pump light is cross-phase modulated (Cross-p
The phase changes greatly in proportion to the control light pulse intensity due to hase modulation (XPM), but the signal light that travels in the opposite direction to the pump light receives the phase change due to the control light pulse on average, and the phase change is the control light Has a small value proportional to the average power of. Therefore, when the optical signal is circulated around the ring of the optical Kerr medium 24 and then combined again by the coupler 19, the phase difference between the signal lights traveling in opposite directions can be made exactly π, and the interference effect at the coupler section causes Signal light is on the other input arm
It is led to 21 and returns to the original input arm 20 when there is no phase difference. Therefore, the control light pulse and the signal light pulse temporally overlapping in the optical Kerr medium 24 are input to the input arm 21, and the non-overlapping signal light pulse is input to the optical circulator through the input arm 20.
The signal light pulse output from 11 can be separated. At this time, the control light is separated from the signal light by the optical splitter 25 at the exit.

In the ring section composed of the optical coupler 19 and the optical Kerr medium 24, only the signal light pulse propagating in the same direction as the control light is output from the output port 27 of the optical demultiplexer 25 (output signal light E), The signal light propagating in the opposite direction to the control light passes through the optical multiplexer 15 and is output from the output port 14 of the optical circulator 11 (output signal F). In this case, an optical circulator 11 having no polarization dependence is used.

(2) Ring type optical multiplexing circuit By reversing the input / output relationship of the above (1) ring type optical demultiplexing circuit, a ring type optical multiplexing circuit can be configured. As shown in FIG. 2, an input signal light G having an arbitrary polarization is multiplexed with a control light having a circular polarization in an optical multiplexer 15 and input to an input arm 20 of an optical coupler 19. The input signal light H having an arbitrary polarization is input from the input port 12 of the optical circulator 11 and guided to the other input arm 21 of the optical coupler 19 via the optical demultiplexer 25. Since the control light in the ring portion composed of the optical Kerr medium 24 and the optical coupler 19 gives a phase change of π to the input signal light G and does not give a phase change to the input signal light H,
Both input signal light G and input signal light H are input arms of optical coupler 19
The multiplexed signal is output to the output port 21 of the optical circulator 11 and output to the optical circulator 11 via the optical splitter 25. In this case, an optical circulator 11 having no polarization dependence is used. The control light is output from the output port 28 in the optical demultiplexer 25 and separated from the output signal light.

[Effects of the Invention] As described above, according to the present invention, time-division separation or time-division multiplexing of signal light pulse trains of arbitrary polarization can be performed stably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a ring type optical pulse separation circuit of the present invention, FIG. 2 is a block diagram showing one embodiment of a ring type optical pulse multiplexing circuit of the present invention, and FIG. 3 (a) is a diagram illustrating the polarization of signal light and control light, and FIG. 3 (b) is a diagram illustrating the polarization of signal light and control light. FIG. 4 is a configuration diagram showing an example of a conventional optical pulse separation circuit. 11 ... optical circulator, 15 ... optical multiplexer (optical multiplexing means), 19 ... optical coupler, 24 ... optical Kerr medium, 25 ... optical demultiplexer (optical multiplexing means).

Claims (2)

(57) [Claims] 1. An optical circulator operating at a wavelength of a signal light, an optical multiplexing means for multiplexing a signal light of an arbitrary polarization state and a control light of a circular polarization, and two output arms for 1: 1 signal light And two input arms, which separate control light to 100% to one output arm
A time-division type comprising: an optical coupler having two output arms; an optical Kerr medium having an optical Kerr effect; and an optical demultiplexer for demultiplexing signal light having an arbitrary polarization state and circularly polarized control light. In the optical pulse separation circuit, one output arm of the optical coupler is connected to one end of the optical Kerr medium, and another output arm is connected to the other end of the optical Kerr medium; A time-division optical pulse separation circuit, wherein the circulator, the optical multiplexing means, the optical coupler, and the optical demultiplexing means are connected in this order. 2. An optical multiplexing means for multiplexing a signal light having an arbitrary polarization state and a control light having a circular polarization, separating the signal light into two output arms 1: 1 and outputting the control light to one output arm. Two input arms and two leading 100% to the arm
An optical coupler having two output arms; an optical Kerr medium having an optical Kerr effect; optical demultiplexing means for demultiplexing a signal light having an arbitrary polarization state and a control light having a circular polarization; A time-division type optical pulse multiplexing circuit having an optical circulator, wherein one output arm of the optical coupler is connected to one end of the optical Kerr medium, and the other output arm is connected to another end of the optical Kerr medium. A time division type optical pulse multiplexing circuit connected to one end, wherein the optical multiplexing means, the optical coupler, the optical demultiplexing means, and the optical circulator are connected in this order.