JP2001526415A - Optical add / drop multiplexer - Google Patents

Abstract

(57) [Summary] An all-optical add / drop multiplexer (ADM) is a nonlinear optical loop mirror having a signal input port (I1), a gate input port (G1), a through output port (T1), and a drop output port (D1). (NOLM) (302, 304). A stream of soliton pulses coupled to the gate input (G1) and synchronized with the soliton signal pulse coupled to the signal input (I1) can be a drop output (D1) or a through output (T1) depending on the presence or absence of solitons in the gate signal. To send a signal pulse. Operations such as logical inversion and logical AND are performed by the NOLM (302, 304), and signals are added by a combination of operations equivalent to a logical sum. Such a combination is used to generate one or more drops and one or more additions in an add / drop multiplexer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION

This application is based on provisional application No. 60 / 067,17, filed on Dec. 10, 1997.
No. 7, claiming this as the priority date of the present application.

[0002]

【Technical field】

The present invention relates to improvements in optical data transmission systems, and more particularly to time division multiplexing of optical soliton signals.

[0003]

[Description of Related Technology]

In certain situations, shape-maintaining pulses of electromagnetic radiation, called solitons, can exist in single-mode optical fibers. Optical transmission systems based on solitons offer extremely high bandwidth possibilities, and numerous soliton optical communications have been disclosed. For example,
U.S. Pat. No. 4,70, entitled Wavelength Division Multiplexed Soliton Fiber Optic Communication System
See 0,339. This patent is hereby incorporated by reference in its entirety. Time division multiplexing (TDM) is a communication system based on solitons.
To take advantage of the extremely high bandwidth provided by combining the low bit rate signal into a high bit rate signal, often by the presence of solitons representing a logical "1" and the absence of a logical "0" Used for In such a system, the relatively low-density soliton streams are combined, each having, for example, a 1 ns time slot, to create a data stream having a 0.5 ns time slot and 2 gigabits per second. (GB).

In telephony applications, as illustrated in FIG. 1, signals are often added to or removed from each other in an “add-drop multiplexer” (ADM). In a digital ADM, a stream of electronic pulses that are relatively densely packed or have a high data rate are referred to as "incoming".
ing) enters the ADM 100 at an input labeled "drop" and has a portion of its data, corresponding to a series of time slots, removed at an output labeled "drop". Sent. The rest of the data is `` outgoing
To another output labeled "." The data transmitted to the outgoing output is combined with the data from the input labeled "add". Data from the add input is inserted into time slots emptied by data sent to the drop output. ADM is implemented in a hybrid format,
The optical signal is converted to a digital electronic signal, removed and added as desired, and ultimately converted from the digital electronic signal to an optical soliton signal. The disadvantages of such a hybrid system are the noise contamination, the potential for increased transmission errors associated therewith, the limited speed of electronic system operation, the relatively expensive operation associated with electronic systems, especially for very high speed signals. And the relatively high cost of electronics equipment.

Hybrid optical ADM limited to operate at tens of gigabits per second
Thus, all optical ADMs provide operation at data rates beyond the capabilities of the hybrid ADM. That is, all optical systems should be able to support data rates of up to 100 GB in the near future and over 1 terabit per second (TB) in the near future, and therefore have a large size compared to hybrid ADMs. The operation speed is increased more than the order. All optical ADMs that reduce both initial price and operating costs
Provides significantly improved reliability and provides extremely high speed operation, and is therefore very demanding and effective.

[0006]

Summary of the Invention

The present invention is directed to an all-optical add / drop multiplexer (ADM) that enables reliable data communication at a bit rate of tens of gigabits per second at low cost.

In a preferred embodiment, an all-optical add / drop multiplexer (ADM)
A plurality of nonlinear optical loop mirrors (NOLMs) having a signal input port, a gate input port, a through output port, and a drop output port are included. The stream of soliton pulses coupled to the gate input is synchronized with the soliton signal pulse coupled to the signal input and directs the signal pulse to the drop output or through output depending on the presence or absence of the soliton in the gate signal. . By directing the gating signals to separate inputs and by using separate NOLM outputs, operations such as logic inversion and AND are performed by the NOLM. The signal is a logical sum "OR
The signal is dropped by the gate control of the NOLM. NOLMs are cascaded to add or drop signals, and the NOLM combination is used to generate one or more drops and one or more additions of an add / drop multiplexer. The above and other features, aspects, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description based on the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION The optical demultiplexer of the present invention suitably includes a non-linear optical loop mirror having a signal input, a gate input, a through output, and a drop output port. A stream of soliton pulses, coupled to the gate input and synchronized with the soliton signal pulse coupled to the signal input, directs the pulse of the signal to a drop output or a through output, depending on the presence or absence of solitons in the gate signal. Such demultiplexers are combined to produce optical add / drop multiplexers (ADMs) at very high data rates, many tens of gigabits per second, providing very reliable and relatively low cost operation. I do.

[0009] Optical soliton communication systems use shape-maintaining light pulses, often with a logical "1".
Transmit the data with the presence of the soliton, interpreted as, and the absence, interpreted as logic "0". For example, US Pat. No. 5,642, entitled “Optical Transmission System”
No. 215, U.S. Pat. No. 5,471,333 entitled "Optical Communication System";
See U.S. Patent No. 5,530,585 entitled "Optical Soliton Transmission System" and U.S. Patent No. 5,523,874 entitled "Optical Soliton Pulse Transmission System". The above patents are all cited in the specification of the present application.

The block diagram of FIG. 2A illustrates a non-linear optical loop mirror (N
OLM) operation. Nonlinear optical loop mirrors are known. See, for example, US Pat. No. 5,655,039, which is incorporated herein in its entirety. N
OLM 200 includes an incoming signal input and a gate input labeled "incoming" and "gate," respectively. The signal leading to the incoming input is sent to a "through" or "drop" output, also labeled in FIG. 2A. For timeslots represented by "1" where the soliton is present at the gate input, the signal at the incoming input is directed to the drop output. Whenever the time slot at the gate input does not include a soliton represented by a "0", the signal at the incoming input is directed to the through output. For example, taking the data stream in the figure, the first time slot read from the left includes “0” at the incoming input and “0” at the gate input. Thus, the incoming input, "0", is sent to the through output, and "0" is sent to the drop output. In the second time slot, the signal at the incoming input is "0" and the signal at the gate input is "1". Therefore, the incoming signal, "0", is sent to the drop output, and "0" is sent to the through output. In this and all subsequent figures, the activation signal is a signal derived from the incoming signal, and is represented by bold characters. For example, the second and fourth drop signals, 0 and 1, respectively, are both shown in bold, indicating that the second and fourth incoming signal values are sent to a drop output. Similarly, the first and third through signal values, 0 and 1, are also shown in bold, respectively, indicating that the first and third incoming signal values have been sent to the through output unit.

FIGS. 2B and 2C are truth tables illustrating the operation of the NOLM 200 with respect to the incoming input I, the gate input G, the through output T, and the drop output D. From the truth table point of view, the value of the drop output is the "AND" of the incoming and gated signals. The value of the through output is the “logical product (AND)” of the incoming value and the negative gate signal. There is some ambiguity in the output of such gates. That is, the presence of a logical zero in the bit stream of the through signal or the drop signal indicates that the corresponding time slot is either "empty" or "clear" or that the time slot is a logical zero for that time slot. Indicates that it has a meaningful bit with a value.

A NOLM, such as the NOLM 200 of FIG. 2A, is used to obtain multiple drop signals,
As shown in the block diagram of FIG. 3, the cascaded NOLM circuits 300 are cascaded. As shown in FIG. 3, the first NOLM 302 includes an incoming soliton data stream labeled "I" and a first gate signal G.
1 are connected so as to be input. The gate signal G1 sends an incoming signal I to generate a first through signal T1 and a first drop signal D1, as described with respect to FIGS. 2A to 2C and shown in bold in FIG. The through output T1 of the first NOLM 302 is connected to the incoming signal input I2 of the second NOLM 304 and is provided as a second gate signal to the gate input G2 of the second NOLM 304. The connection of the NOLMs 302 and 304 generates a second through T2 and a drop D2 output. The first gate signal G1 sends an incoming signal to the first drop output Dl for each of the other time slots beginning with the second time slot. The remaining time slots of the incoming signal are further divided between the T2 and D2 outputs by the gate signal G2. This gate signal G2 is
In the first time slot equal to 0, the first active time slot of the T1 output is sent to the through output T2, and in the third time slot equal to 1, the second active time slot of the through signal T1 (ie time slot 3). ) To the second drop output D2. In this way, the first drop signal D1 carries half of the incoming signal I, while each of the second drop signal D2 and the second through signal T2 is four times the incoming signal I. Convey one-half. In general, this method can be extended to produce N drop signals by sending the (N-1) th through output to a further cascaded NOLM. In this further cascaded NOLM, the (N-1) th through output is gated with the Nth gate signal to generate an Nth drop signal. The separate gate signals G2-GN are provided appropriately.

[0013] The NOLMs may also be cascaded by drop outputs to produce multiple drop outputs. In the combination of FIG. 4, the N-th drop signal is
It is created by gating the (N-1) th drop output with the Nth gate signal to produce a drop output. The NOLM 402 receives the incoming data stream at the incoming input I1, and the gate input signal at the gate input G (1: N), and according to the description related to FIG. D (1: N) signal. In this embodiment, the drop output Dl carries data of each of the other incoming signal time slots. The outputs D (2: N) and T1 divide the rest of the data of the incoming signal. In this embodiment, the G (1: N) gate signal is dropped from the incoming signal, and
1, D2,. . . This shows the total number of time slots for generating the DN signal. G (2
: N) signal whose G2 may be provided from the T1 output of the NOLM 302 in FIG. 3, for example, which timeslots are dropped and D2, D3,.
Indicates whether a signal should be made.

As shown in FIGS. 2-4, a NOLM can be used in accordance with the present invention to remove bits from an optical bit stream, which in the preferred embodiment comprises solitons.
That is, the NOLM can be suitably used to provide the desired "drop" of the ADM. An all-optical "OR" circuit consisting of a NOLM is highly desirable to create the "ADD" function of the ADM. The basic function of the desired adder circuit 500 is shown in the block diagram of FIG. 5A. Summing circuit 500 is connected to receive a through signal according to the preferred embodiment and includes an input section T and an input section A connected to receive a through signal and an add signal. Assume that the signals guided to the T and A inputs do not overlap. In other words, the active time slot of one signal coincides with the inactive time slot of another signal. Active time slots are indicated by bold letters, a first time slot is active for the T signal, inactive for the A signal, and a second time slot is for the T signal. Inactive and active for the A signal. The added signal is available at output O and is the "OR" of the T and A signals. And since each of the other time slots is active for each of the added signals, the output signal O is active for each time slot, as indicated by the bold string. The truth table of FIG. 5B describes the result of the logical combination at the inputs T, A. "1+
The combination of "1" is not allowed as one of the inputs and therefore must be inactive and is a logic zero.

The truth table of FIG. 6 provides an example of a change in DeMorgan's law. This is the signal T
, A is equivalent to the “logical product (AND)” of “not A (Not A)” and “not T (Not T)”. As discussed with respect to FIG. 2C, the D output of a NOLM constructed in accordance with the present invention provides an "AND" of inputs I and G. In the block diagram of FIG. 7, the source of the soliton is
Provides a stable stream of logic "1" for each time slot. The stream of logic "1" is coupled to the incoming input of NOLM 700, and the inverted signal, labeled T, is coupled to the gate input of NOLM 700. The signal T is available at the NOLM 700 drop output, the negation of which is NOT T, is generated at the NOLM 700 through output.

The block diagram of FIG. 8 shows a NOLM combination according to the present invention that preferably provides an all-optical ADM implementation with optical solitons. This embodiment of the ADM 800 includes a single additional input and a single drop output. NOLM 802 is connected to receive an incoming signal at input I1 and a gate signal at gate input G1.
An ADM through signal and a drop signal are generated. As described above, NOLM80
2 generates a through signal at the through output section T1 and a drop signal at the drop output D1. The output signal from the drop output section Dl forms the drop output section of the ADM, and the output signal from the through output section T1 forms the input signal T to the gate input section G2 of the NOLM 804. The incoming input I2 of the NOLM 804 is connected to receive a stable stream of solitons, as indicated by a "1" at the input. As described with reference to FIG.
, A "NOT T" output is generated at the through output section T2. This signal is connected to the incoming input I5 of a further NOLM 806.

An additional input (ADD input) of the ADM 800 is formed by the incoming input I 3 of the NOLM 808. The additional input signal and the incoming input signal are synchronized for proper operation. That is, the additional signal occupies the time slot occupied by the drop signal, and the additional signal is preferably gated by the same gate signal as the NOLM 802 gate signal. The gate signal coupled to the input G3 of the NOLM 808 is the signal A at the drop output D3 of the NOLM 808.
Generate

This signal A is connected to the gate input G 4 of the NOLM 810, and a stable stream of “1” is provided to the incoming input 14 of the NOLM 810. That is, NOLM 810 is connected to generate a negation of signal A at through output T4. This signal, i.e., "NOT A" is connected to the gate input G5 of NOLM806. The drop output D5 of the NOLM 806 is NO
The output signals coupled to the gate input G6 of LM 812 produce "NOT T" and "NOT A". A stable stream of "1" is provided to the incoming input I6 of the NOLM 812. Therefore, NOLM8
12 provides to the through output T6 the negation of the signal at the gate input, that is, the product of (not T) and (not A) ((NOT T) AND (NOT A)). This is equal to the sum of T and A (T OR A) according to De Morgan's law. In short, a drop component appearing in the drop output D1 of the NOLM 802 is removed from the incoming signal. The remaining one, the through signal, is added to the signal add (Add), which is coupled to the incoming input 13 of the NOLM 808 and the resulting sum of add and through ( Add OR Through h) is provided to the through output T6 of NOLM 812. The NOLM NOT circuit includes NOLMs 804, 810, 812, all receiving a stable stream of solitons. This stable stream of solitons is provided by combining three generators or a single soliton generator with a splitter. The time phasing at the inputs of all NOLMs is properly matched.

An all-optical ADM according to the preferred embodiment of the present invention is shown in the block diagram of FIG. NO
The LM 902 divides the incoming signal labeled “incoming” into a through signal and a drop signal, for example, as described with reference to FIG. NOL
M904 is connected to invert the through signal, which causes NOLM9
06, which is coupled to the incoming input I3, i.e., "NOT T (NOT
T) "is generated. The additional signal labeled "Add" is coupled to the incoming input I4 of the NOLM 908 and is gated by a signal coupled to the gate input G4 of the NOLM 908. In this embodiment, the gate signal used at the input G4 is the same as that at the input G1. This ensures that the additional signal occupies the same time slot as the drop signal. The gated additional signal A is coupled to the gate input G3 of the NOLM 906, and the through output T3 of the NOLM 906 has an output signal, the product of (not T) and (not A) ((NOT T) AND (NOT A). ))I will provide a. This signal is coupled to the gate input G5 of the NOLM 910, which, with the stable stream of "1" coupled to the incoming input I5, inverts the signal, thereby ORing the through signal and the additional signal. To provide the desired outgoing signal.

As discussed based on FIGS. 3 and 4, NOLMs are cascaded to create multiple drop outputs. Similarly, as shown in the truth table of FIG.
The OLM is cascaded to create a plurality of additional signals, thus allowing for the assembly of an all-optical ADM with multiple drop outputs and multiple additional inputs. FIG.
Shows a combination of two additional inputs and a through input. Typically, the number of additional inputs is increased by ANDing the negation of the first additional signal, labeled A1 in the table, with the through signal. Next, the negation of the next additional signal, entitled A2 in the table, is ANDed with the result of the previous AND operation. This process is repeated until all desired additional signals have been combined. Next, the result of the previous step is negated or inverted. The results, entitled "NA" in the table, indicate that the combination of signals overlaps with "1", i.e., is not allowed so that another signal competes with the timeslot.

The block diagram of FIG. 11 shows a combination of NOLMs. This combination of NOLMs
According to the principles of the present invention, multi-add, multi-drop
-Drop-drop) The all-optical ADM 1100 is formed. The three NOLMs 1102, 1104, 1106 are cascaded to generate three drop signals, drop, drop, and drop 3, respectively. The through signal provided by NOLM 1106 is provided to NOLM 1108 and inverted. The additional signal Add1 is NOL
Received and gated at M1110 to generate a signal A1, which is
It passes through the gate input of NOLM 1116. The NOLM 1116 combines the gated signal A1 with the inverted through signal to generate a logical product of (not T) and (not A1) ((NOT T) AND (NOT A1)). Similarly, the second additional signal Add
2 is gated by the NOLM 1112 and the gated signal A2
Generate The gate-controlled signal A2 is output from the NOLM 1118 to the NOLM 1118.
Combined with the result output from 1116, the output NOT ((NOT T) AND (NOT A1)) AND
(NOT A2) is generated. The N additional signals are thus combined with each of the previous results ANDed with the gated additional signal AN, as provided by the NOLM 1114 to the NOLM 1120. Next, the end result is NO
The outgoing signal is inverted at LM 1122 and labeled outgoing.

A NOLM device is effectively formed by the present invention, as shown in the block diagram of FIG. The NOLM 1200 includes a coupler 1202 attached to a single optical fiber forming a loop 1204. Loop parameters such as its length,
The effective area of the loop, the rate of change of dispersion in the fiber, etc., depending on whether the width or amplitude is above or below a predetermined threshold value, the input pulse is switched,
Or selected to be able to send.

The operation of a NOLM is well known and can be summarized as follows. Coupler 1202 is
If the input light pulse received at either of ports 1206, 1208 is split into two equal counter-rotating pulses and the loop affects these component pulses symmetrically, then the component pulses are: Upon returning to coupler 1202, they interfere constructively, such that the input pulse is reflected back through the port,
Enter the loop mirror. If the pulse is split unevenly or the loop affects the pulse symmetrically, the pulse returning to the coupler will be reflected to the entry port, transmitted to the other port of the coupler, or partially reflected Or partially transmitted.

In the preferred embodiment of FIG. 12, loop 1204 is operatively connected to couplers 1210, 1212 that operate as wavelength division multiplexers. One port of the coupler 1210 operates as a gate input and is labeled accordingly. The input gate pulse is preferably formed of light having a wavelength different from the wavelength of the pulse of the incoming signal in order to prevent unnecessary coupling. Alternatively, the pulses may have the same wavelength but different polarizations. The incoming signal is input at one port of the 3 dB coupler 1214 labeled incoming. Alternatively, a circulator is used to reduce loss
14 may be substituted. The NOLM 1200 operates as described above with respect to the block diagrams shown in FIGS. 2A-2C due to the presence of a gate signal to send the incoming signal to the drop output and the absence of a gate signal to send the incoming signal to the through output. That is, the output labeled "through" is the logical product of the inversion of the gate input and the incoming input. The output labeled drop is the logical AND of the incoming and the gated input. The pulse appearing at the gate input is coupled out of the loop by coupler 1212.

The foregoing description of a specific embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible within the teachings above. The embodiments have been chosen and described in order to explain the principles and embodiments of the present invention, and those skilled in the art can best use the present invention. The scope of the present invention is limited only by the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional electronic add / drop multiplexer.

FIG. 2A shows a block diagram of a nonlinear optical loop mirror (NOLM) according to the present invention.

FIG. 2B shows a through output truth table for a nonlinear optical loop mirror (NOLM) according to the present invention.

FIG. 2C shows a drop output truth table for a nonlinear optical loop mirror (NOLM) according to the present invention.

FIG. 3 is a block diagram illustrating a cascade of NOLMs according to the present invention that produces multiple drop outputs.

FIG. 4 is a block diagram illustrating another method of cascading a NOLM according to the present invention that produces multiple drop outputs.

FIG. 5A is a block diagram of an OR function that has been found to be effective in implementing an ADM according to the present invention.

FIG. 5B is a truth table of an OR function that has been found to be effective in implementing an ADM according to the present invention.

FIG. 6 is a truth table showing the conversion between logical product and logical sum operations enabling drop and additional multiplexing of the NOLM according to the present invention.

FIG. 7 is a block diagram of a NOLM connected to invert or negate an input signal according to the present invention.

FIG. 8 is a block diagram illustrating combinations of NOLMs connected to produce a 1-drop 1-add ADM according to the present invention.

FIG. 9 is a block diagram of another combination of NOLMs that produce a 1-drop 1-add ADM according to the present invention.

FIG. 10 is a truth table used to show a method of performing multiple addition in the ADM of the present invention.

FIG. 11 is a block diagram of a 3-add 3-drop ADM according to the present invention.

FIG. 12 is a block diagram illustrating one suitable embodiment of a NOLM for use with the present invention.

[Procedure amendment]

[Submission date] June 28, 2000 (2000.6.28)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, GH, GM , HR, HU, ID, IL, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, V N, YU, ZW F term (reference) 2K002 AA02 AB04 BA02 DA07 GA10 HA16 5K002 BA04 BA06 BA21 DA03

Claims (15)

[Claims] 1. A first nonlinear optical loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port, wherein the first loop mirror transmits an incoming signal. A first non-linear signal receiving and separating the signals into two signals whose time slots do not overlap, one of the two signals being provided to a through output port and the other being provided to a drop output port An optical loop mirror; a second nonlinear optical loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port; Receiving one of the two divided signals from the loop mirror and dividing the divided signal into two non-overlapping time slots. Light multidrop multiplexer for the second nonlinear optical loop mirror, characterized in that it consists coupled to divide into that signal. 2. A first non-linear optical loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port, wherein the first loop mirror has a time slot overlapping. A first nonlinear optical loop mirror that receives two incoming signals that do not meet one another and combines the signals to generate at least one of a through signal and a drop signal that appear at a through output port or a drop output port, respectively; A loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port, wherein one of the through signal and the drop signal does not overlap a time slot with the received signal. And a time slot overlaps with the received signal. Light Multi add multiplexer for the second nonlinear optical loop mirror which is connected to further combine the signals have, in that it consists characterized. 3. A first nonlinear optical loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port, receiving an incoming signal and receiving the incoming signal. A first nonlinear loop mirror connected so as to separate a through signal and a drop signal whose time slots do not overlap, and a second nonlinear optical loop mirror, wherein an incoming signal input port and a gate input port are provided. And a second nonlinear optical loop mirror having a through output port and a drop output port, wherein the first loop mirror converts an additional signal and the through signal from the first loop mirror into an additional signal. Connected, the two signals do not overlap in time slots and the first loop mirror further combines the signals. Optical add / drop multiplexers, characterized in that connected to. 4. A soliton source connected to generate a stream of solitons, and a non-linear optical loop mirror, the loop mirror comprising an incoming signal input port, a gate input port, a through output port, and a drop output. A port, wherein the loop mirror receives a first optical signal comprising a stream of solitons and a second optical signal at the incoming input and the gate input, respectively, and the signal at the drop output port And a logical AND of the signals at the incoming input and an inversion of the signal at the gate input at the through output. Logical inverter. 5. A non-linear optical loop mirror having an incoming signal input port, a gate input port, a through output port, and a drop output port, wherein the mirror is connected to a logical product gate and a logical inverting gate and complies with De Morgan's law. An optical OR gate characterized in that the gates are combined to produce a logical OR gate in response. 6. A first non-linear optical loop mirror having an incoming signal input, a gate input, and a drop output port, the first loop mirror receiving the incoming signal and the gate signal, and receiving at the drop output port. A second non-linear optical loop mirror connected to generate a drop signal, the second loop mirror having an incoming signal input, a gate input, and a drop output port; An optical multi-drop multiplexer which receives a drop signal from a first nonlinear optical loop mirror at its incoming signal input and is connected to produce a further drop signal at its drop output port. 7. The optical multi-drop multiplexer according to claim 6, wherein the incoming signal input of the first nonlinear optical loop mirror comprises a stream of soliton pulses. 8. The gate signal of the first nonlinear optical loop mirror comprises a stream of alternating current soliton pulses synchronized with the incoming signal input of the first nonlinear optical loop mirror, and the incoming signal of the first nonlinear optical loop mirror. The optical multi-drop multiplexer according to claim 7, wherein the AC time slot of the signal input is directed to a drop output port of the first nonlinear optical loop mirror. 9. The one or more additional nonlinear optical loop mirrors are connected such that a third nonlinear optical loop mirror receives an additional drop signal from the second nonlinear optical mirror and produces an additional drop signal. 7. The optical multi-drop multiplexer according to claim 6, wherein the cascade connection is performed so that an appropriate desired number of drop signals are obtained. 10. A non-linear optical loop mirror having an incoming signal input, a gate input, and a through output port, wherein the first loop mirror generates an incoming signal and a gate signal, and A second nonlinear optical loop mirror connected to produce a through signal at the through output port and having an incoming signal input, a gate input, and a through output port, wherein the second loop mirror has its incoming signal input; Wherein the optical multi-through multiplexer is connected to receive a through signal from the first nonlinear optical loop mirror and generate a further through signal at the through output. 11. An incoming signal input of a first nonlinear optical loop mirror,
The optical multi-through multiplexer according to claim 10, comprising a stream of soliton pulses. 12. The gate signal of the first nonlinear optical loop mirror comprises a stream of alternating current soliton pulses synchronized with the incoming signal input of the first nonlinear optical loop mirror, and the incoming signal of the first nonlinear optical loop mirror. The optical multi-thru multiplexer according to claim 11, wherein the AC time slot of the signal directs a first nonlinear optical loop to a through output port of a mirror. 13. The one or more additional non-linear optical loop mirrors such that the third non-linear optical loop mirror receives additional through signals from the second non-linear optical mirror and produces yet another through signal. 11. The optical multi-thru multiplexer according to claim 10, wherein a desired number of drop signals are obtained in a cascade connection so as to be connected. 14. The optical multi-thru of claim 10, wherein a gate input of the second nonlinear optical mirror is connected to receive a through output signal of the first nonlinear optical mirror as its gate signal. Multiplexer. 15. A first nonlinear optical mirror comprising a first coupler attached to one optical fiber forming a loop, said loop operatively connected to a second coupler for coupling a gate signal. The optical multiplexer according to any one of claims 1, 2, 3, 6, and 10, wherein: