Controlled optical multiplexer

FIELD: physics.

SUBSTANCE: controlled optical multiplexer includes a multiple-step structure of filters having elements for controlled adjustment of transfer constants. The optical filters used are asymmetrical Mach-Zehnder interferometres: single-stage and/or two-stage, and/or multistage. Electro-optical or thermo-optical phase-shift devices serve for controlled adjustment of transfer constants of the optical filters. The multiplexer can be made on integrated-optical technology in form of a monolithic solid-state device.

EFFECT: controlled multiplexing of channels in the fibre optic communication system with wavelength-division multiplexing of channels, whose optical frequencies can be adjusted for constant spectral interval neighbouring channels Δν.

7 cl, 9 dwg, 2 tbl

 

The technical field

The invention relates to fiber-optic communication systems (hereinafter VOSS) with multiplexing, in particular controllable optical multiplexor devices, and can be used in systems dense spectral multiplexing (hereinafter - DWDM) and moderate spectral multiplexing (hereinafter CWDM).

Prior art

Technology spectral multiplexing, using modern approaches, allow us to satisfy the existing requirements for bandwidth VOSS. However, to meet new and increasing demands from developers of communications systems, further improvement and expansion of facilities. One of directions of development of technologies spectral multiplexing is connected with approach, in which the carrier frequencies of the channels to be dynamically tunable.

Known and there are tunable in a wide spectral range devices are laser diodes, and also managed optical multiplexers I/o. For communication systems with wavelength division multiplexing channels is also required optical multiplexers with tunable optical carrier channels (hereinafter - managed optical multiplexers).

Managed optical mul is plexor can be used for the basic purpose - as a device for combining and input channels in the optical path. They can also be part of more complex devices and systems for spectral multiplexing of dynamic functionality, such as multi-managed multiplexers I/o.

Managed optical multiplexers can also be applied in multi-channel systems, sensors, optical analog systems for various purposes, for optical filtering and other purposes.

To date, developed and used optical multiplexers of different types. This multiplexers in the multistage structures on the interference filters or diffraction gratings, multiplexers in the planar performed on the so-called phased array wiring (AWG), and finally, closest to the present invention a multi-stage tree structure based on the unbalanced interferometers, Mach-Zehnder interferometers (EMC).

It is known that the EMC is characterized by low optical loss and low polarization dependence. The structure of the EMC with the number of steps 8-9 characterized by high selectivity and are able to cover the full spectral band used in systems for spectral multiplexing.

Famous traditional design of the multiplexer on the EMC intended for the use of the Finance in fiber-optic communication systems with wavelength division multiplexing 2 Nchannels and frequency spacing between adjacent channels Δν, is an N-stage structure of type "tree"that contains every n-th stage 2N-nThe EMC. The multiplexer has a 2Ninputs for submission to each one input channel and one output for multiplexed optical signal.

When it arrives at each input of such a device channels, subject to multiplication, the EMC in the first stage combine channels 2N-1groups. Each group is directed to the second stage, in which the channels come together again, now in the 2N-2groups. This process of merging groups (and channels) continues with the passage of the radiation sequentially through each stage of the multiplexer. Finally, on the last step, all channels are fully merged into one thread (the optical signal).

Optical multiplexers on the basis of the EMC, as well as others listed above multiplexers in the vast majority are static, i.e. have a fixed spectral characteristics and therefore cannot be used in VOSS with multiplexing, in which frequency channels dynamically rebuilt.

It is also known that the single-stage EMC with elements of the phase shift, can be key elements in the managed optical multiplexer input/output (US, 675654, B2). Obviously, when properly applied, they could also become the basis for creating a managed optical multiplexer.

Modern optical technology provides a wide range of the EMC, which can be used in multiplexers, including dynamic functionality. The basic and the simplest structure is asymmetrical single stage of the EMC (next - single-stage the EMC).

The disadvantage of the single-stage EMC is a non-ideal shape of the spectral characteristics, which when used in systems spectral multiplexing with a high density of channels can cause crosstalk and poor insulation channels. Much better spectral characteristics have two asymmetric EMC and asymmetrical multi-stage EMC (next - two-stage and multistage recognized. The modules of the EMC, in addition, are characterized by a significantly lower insertion dispersion.

It is obvious that managed optical multiplexer, which could be made in the form of a multi-stage structure including a sufficiently large number of the EMC should be maximally protected from the effects of environmental temperature instability, vibrations, etc. Therefore, to provide the necessary stability and reliability of the device must have a high degree and the integration used the EMC and to be compact; the most appropriate technology for the manufacture of such devices can be integrated optical technology.

Disclosure of inventions

The present invention aims at creating a managed optical multiplexer systems for spectral multiplexing of dynamic functionality. The multiplexer must meet existing requirements for isolation channels and make dispersion and be suitable for integrated optical implementation.

While the invention has been tasked to provide a method and device for spectral multiplexing of multiple channels from a multichannel optical signal by controlling the spectral characteristics of the filter stages of the multiplexer.

The task was solved by providing a method of controlled multiplexing of channels in the fiber optic communication system using wavelength division multiplexing 2Nchannels, optical frequencies with a constant spectral interval between adjacent channels Δν can be reconstructed, in which:

(a) serves 2Nchannels, each channel separately, 2Ninputs N-stage structure of type "tree"that contains every n-th stage when n=1, 2, ..., N 2N-noptical filters having two inputs and at least one output, made with prob is the possibility of a managed realignment transmission ratios and characterized by a frequency interval between adjacent extrema in the dependency ratios of the transmission frequency Δν n=2n-1Δν, and inputs the specified N-stage structure are each of the two inputs of each optical filter of the first stage;

(b) configuring the optical filter of each stage so that the optical frequency of each of the 2Nchannel coefficients of the transmission with one of the 2Ninputs specified N-stage structure on the output would have a maximum value;

(C) transmit the multi-channel optical signal through the N-stage structure and receive the output of the optical filter last degree multi-channel optical signal.

The task was solved by creating a managed optical multiplexer for use in fiber-optical networks with wavelength division multiplexing 2Nchannels, optical frequencies with a constant spectral interval between adjacent channels Δν can be reconstructed, including:

N-stage structure of type "tree"that contains every n-th stage when n=1, 2, ..., N 2N-noptical filters made with the possibility of a managed realignment transmission ratios, characterized in n-tier frequency interval between adjacent extrema in the dependency ratios of the transmission frequency Δνn=2n-1Δν and having two inputs and at least one output;

- pin the Oller to manage the rebuilding of the transmission coefficients of these filters.

Thus according to the invention is advisable to specified multi-stage structure:

- two inputs of each optical filter of the first stage were connected to one of the input ports;

optical filters in each stage, except the first, were connected to each of the two inputs with the output of one of the optical filters of the previous stage;

the output of the optical filter of the last stage was connected with the output port.

Thus according to the invention, it is expedient to optical filters multi-stage structures were single-stage and/or two-stage and/or multi-stage unbalanced interferometers, Mach-Zehnder interferometers, and to manage the configuration of the transfer coefficients of the optical filters contained electro-optical or thermo-optical device of the phase shift.

In addition, according to the invention it is expedient that the multiplexer was performed on the integrated optical technologies on a single chip.

Thus according to the invention it is advisable that all multiplexer input ports and output ports were performed using optical fibers.

Thus, according to the invention controlled optical multiplexer is a multi-stage tree structure on optical filters, each of which combines the odd and even channels and e has the elements for managed realignment spectral characteristics.

In the General case one multiplexer according to the invention as an optical filter can also be used with optical filters of different types: single-stage, two stage and multi-stage of the EMC. In the first stages of multi-stage structure, where the input of receive channels with a small spectral interval used two-stage and even the single-stage EMC, increasing the spectral interval between the channels in the subsequent stages are the modules of the EMC.

For managed realignment of the spectral characteristics of the optical filters used electro - or thermo-optical device of the phase shift. Managed external device phase shift provides the reconstruction of the spectral characteristics of optical filters and as a result the necessary adjustment of the spectral characteristics of all managed optical multiplexer. The use of electro-optical phase shift device ensures extremely high speed managed realignment spectral characteristics of managed optical multiplexer.

Brief description of drawings

The invention is further explained in the description of embodiments of the method of the managed optical multiplicitive channels using managed optical multip is exora according to the invention and the accompanying drawings, showing:

Figa diagram of a known single-stage MTS,

Figb - cosmetic-known single stage of the EMC shown in Figa,

Figure 2 - dependence of the transmission coefficients from the optical frequency for the single-stage EMC shown in Figa,

Figa diagram of a known two-stage MTS,

Figb - cosmetic-known two-stage MTS, shown in Figa,

Figure 4 - dependence of the transmission coefficients from the optical frequency for two of the EMC shown in Figa,

Figa diagram of a known multi-stage of the EMC with zero or nearly zero dispersion comprising three two-MTS,

Figb - cosmetic-known multi-stage filter shown in Figa,

6 is a diagram of one of the options controlled optical multiplexer according to the present invention.

The best option of carrying out the invention

According to the invention the main element of the controlled optical multiplexer is unbalanced interferometer Mach-Zehnder or as agreed to call him, one stage of the EMC. This is a known and commonly used in optics device (Mogp, E.Wolf. "The Optic Base", Pergamon Press, Oxford, Fifth Oxford, Fifth Edition, 1975, pp.312-316; Translation into English: Mborn and Evolv. "Principles of optics". TRANS. edited Gpotool.exe. M, N is indicated, 1970, s-346).

Single stage of the EMC can be performed using various components and technologies, including the use of fiber optic splitters, beam splitters, mirrors, prisms, polarizers. Optimal for use in a multi-stage structure is a single stage of the EMC in the planar implementation.

On Figa shows a schematic depiction of the waveguide single-stage variant of the EMC 10, its conventional image shown in Figb.

The device 10 is placed on the same substrate 11 where the single stage of the EMC 12 is formed located between the first 13 and second 14 splitters the two arms 12-1 12-1 and formed by waveguides of unequal length, 11and 12respectively. The coupling coefficients k1and k2splitters 13 and 14 are equal and divide the optical power 50/50. The single-stage EMC 12 conclusions a and b on one side and conclusions C and d on the other side.

This single stage of the EMC shoulder 12-2 contains the device 15 phase shift, which is a managed element that is used to adjust the spectral characteristics, and may introduce additional phase shift φ in the phase of the passing wave.

The magnitude of the phase shift φ is controlled by thermo-optical or electro-optical effect using electric current or voltage is Oia. Accordingly, the device 15 phase shift can be produced using thermo-optical material, such as silicone, or the electro-optic material such as lithium niobate (LiNbO3) or gallium arsenide. Such phase shift device known in the art spectral multiplexing as a tool to adjust the spectral characteristics of optical filters based on the EMC, and are also used in other devices, modulators and switches.

When the input port and the radiation unit capacity of the intensity of light at the two output ports C and d can be expressed: using the transfer factors

Kac(ν, φ) and Kad(ν, φ):

where D=2πnΔLν/c is the phase delay due to different optical length shoulder 22-1 22-1 and; ΔL=l1-l2; n is the refractive index of the material, ν is the optical frequency and C is the speed of light in vacuum.

When excited through port b of the light intensity in the same output ports C and d can be represented using the transfer coefficients of the Kbc(ν, φ) and Kbd(ν, φ):

Considered at any frequency ν (or wavelength λ) coefficients of transmission (1)÷(4) be the spectral characteristics of nakasaleka of the EMC. As you can see, the spectral characteristics (1)÷(4) are periodic functions of the light frequency ν and wavelength λ, the difference of the lengths of the shoulder ΔL, the refractive index n and the phase shift φ.

For the health of a single stage of the EMC significant following properties:

- the distance between adjacent extrema in the spectral characteristics (1)÷(4) in units of optical frequency Δν and in units of wavelengths Δλ is equal to:

- transfer coefficients of the (1)÷(4)corresponding to the optical transition radiation from a single input port to two output ports, but differ phase by π;

the transmission ratios when replacing the two indices do not change, that is,

Kad(ν, φ)=Kbc(ν, φ) And Kac(ν, φ)=Kbd(ν, φ);

- changing the value of the phase shift φ, it is possible to modify the spectral characteristics (1)÷(4)by sliding them along the axis of the frequencies (wavelengths); this leads, in particular, when the change of the phase shift δφ=±π inversion of the signals at the outputs;

the transmission ratios are not changed when the permutation of the indices, i.e. single stage of the EMC is a reversible device.

In turn, from these properties it follows that when input single stage of the EMC optical signal containing multiple channels, frequency wavelengths (wavelengths), which coincide with the position ekström the MOU in the dependency ratios of the transmission frequencies (wavelengths), the signals are divided into two groups, which are displayed on different outputs. One group contains an odd channels, the other group - even channels, in both groups the spectral interval between channels becomes two times greater than the input one stage of the EMC. Upon receipt of the same optical signal to another input of the odd and even channels at the outputs are swapped.

As one stage of the EMC is a reversible device, in another situation, when one input serves odd channels, and the other input serves the even channels, both channels are combined into one optical flow with a dense arrangement of channels.

Devices that perform the function of the separation channels on odd and even reverse function, combining odd and even channels into one stream in foreign literature called interlibrary; in the literature there is no term for devices of similar purpose and in the present invention they are referred to as optical filters.

The distance between adjacent extrema Δν (or Δλ) in the spectral characteristics for the real single stage of the EMC should be formed at the stage of its manufacture by selecting the corresponding difference of the lengths of the shoulder L and refractive index n. Managed the reorganization provisions of the extreme values of the coefficients in front of the Chi relative to the set of frequencies {ν i} (or wavelengths {λi}) must be made using the appropriate adjustment of the phase shift φ when using the optical filter as part of any specific device.

Neither Figure 2 shows the transfer coefficients of the Kac(ν, φ) and Kad(ν, φ) as a function of optical frequency for a single stage of the EMC, which, when the respective values of phase delay D and the phase shift φ is the distance between adjacent extrema 50 GHz and can thus be used to combine odd and even channels into one common stream with the spacing between adjacent frequency channels 50 GHz. Solid lines show the spectral dependence of the transmission coefficient Kac(ν, φ), in which one group of channels is odd channels is outputted from, the dotted lines show the spectral dependence of the transmission coefficient Kad(ν, φ), responsible for the output of another group of channels, even channels on exit d.

As you can see in figure 2, the disadvantage of this optical filter is non-planar vertices and slowly falling edge lines of the spectral bands in a small spectral interval between channels may cause crosstalk between adjacent channels. Another well-known disadvantage is that when a large difference of the lengths of the shoulder ΔL variance can be quite large (US, 6782158, In). These shortcomings limit the possibility of using single stage of the EMC in the devices used in communication systems with wavelength division multiplexing channels.

A significant improvement in spectral characteristics of optical filter devices and systems for spectral multiplexing provide, as you know (US, 6782158, B), two of the EMC, which can be done using fiber optic splitters, beam splitters, mirrors, prisms, polarizers, and other devices and integrated optical form, and contain this device phase shift.

On Figa shows a schematic depiction of the waveguide two-stage variant of the EMC 30, its conventional image shown in Figb. It uses three splitters 31, 32 and 33 with the coupling coefficients k1, k2and k3accordingly, forming two single stage of the EMC 34 and 35. The device 30 is placed on a single substrate 36.

The first single stage of the EMC 34 is formed by two waveguides 34-1 and 34-2 unequal length l34-1and l34-2respectively. The second single stage of the EMC 35 is formed by two waveguides 35-1 and 35-2 unequal length l35-1and l35-2respectively. Phase delay D1=2πn(l34-1-l34-2)/λ and D2=2πn(l35-1-l35-2)/λ are connected by the relation D2=2·D1.

In the EMC 4 and 35 are used, the phase shift device 37 and 38, which make the phase shifts φ and ϕ, respectively. The two-stage EMC has conclusions a and b on one side and conclusions e and f on the other side.

The spectral characteristics of the two-stage EMC 30 it is easy to obtain analytically. For three splitters 31-1, 31-2 and 31-3, you must enter the matrix T(ki) (i=1, 2, 3), which relate the amplitude of light at the input and output parameters splitters:

and for the two single stage of the EMC 33 and 34 - matrix T(D1) and T(D2):

Then the matrix bandwidth M(ν, φ, ϕ) are two of the EMC is determined by the product of the five matrices:

Since the coefficients of the two-stage gear of the EMC connect the optical output intensity from the optical intensity at the input to determine the use of the expression:

From expressions (6)÷(9) can be obtained all the basic properties of two of the EMC. It is easy to check that two of the EMC at the input radiation through the ports a and b remains a device for splitting and merging odd and even channels. So, when applying the optical signal to the port a certain stage of the EMC channels will be divided into two groups containing one band - odd channels, and the other band - even channels. totem important property, the remaining two of the EMC when applying the same optical signal to another input port on Figa, groups with odd and even channels are reversed on the output ports e and f.

The distance between adjacent extrema Δν and Δλ in the spectral characteristics are also determined by the expressions (5), where ΔL is the path difference in the first stage of the two stage of the EMC 40, that is, ΔL=l44-1-l44-2. Still managed shift of spectral characteristics now using two phase shifts φ and ϕ. To shift the spectral characteristics of the Kae(ν, φ, ϕ) and Kaf(ν, φ, ϕ) along the frequency axis by the value of δν, you must use the appropriate devices phase shift change of the phase φ and ϕ:

You can also check by using (6)÷(9)that when the input signal through the ports e and f is lost can be divided into odd and even channels and respectively combining odd and even channels. This is a consequence of the fact that the matrix in accordance with the expression (6) and (7) are non-switched. Therefore, two of the EMC appear reversible devices - two ports a and b on the one hand can only be used as input ports, and the other two ports e and f on the opposite side - just as output ports.

Figure 4 shows the transfer coefficients of the Ka who (ν, φ, ϕ) and Kaf(ν, φ, ϕ) for some stage of the EMC as a function of optical frequency, calculated using expressions (6)÷(9). This stage of the EMC when the coupling coefficients k1=0.7854, k2=2.0944, k3=0.3218 respective phase delays of D1and D2and the phases φ and φ can be used as a 50 GHz optical filter for combining even and odd channels into a common flow channel spacing between adjacent frequency channels 50 GHz. Solid lines show the spectral dependence of the transmission coefficient Kac(ν, φ, ϕ), according to which when the input port and one group of channels (odd channels) is displayed on the output e, the dotted lines show the spectral dependence of the transmission coefficient Kaf(ν, φ, ϕ), responsible for the output of the other channel groups (even channels) output f.

As you can see, the two-stage EMC has a much better form of spectral characteristics close to rectangular, with flat top and steep decline at the edges of the spectral bands. Therefore, two of the EMC used as the optical filter provides the best suppression of crosstalk and high isolation channels. However, insertion two-stage dispersion of the EMC remains high and therefore use it as a filter in communication systems with high speed re the ACI limited data.

It is known that the situation can be changed for the better when using filters obtained by cascading two of the EMC. In one embodiment, such devices can be used complementary to two of the EMC has the same transmittance, but opposite in sign to the dispersion. The complementarity of the two-stage of the EMC provides a certain ratio of the coupling coefficients k1, k2and k3used two of the EMC (US, 6782158, B2).

On Figa shows one variant of the multi-stage EMC 50, which can be used to combine odd and even channels; conventional multistage image of the EMC is shown in Figb. The device 50 in the waveguide performance placed on a single substrate (chip) 51 and includes three two-stage of the EMC; in the first stage uses two dual-stage of the EMC 52 and 53, both type I and second cascade - two of the EMC 54 type I', that is, with the opposite sign of dispersion.

When the input odd and even channels, respectively, through an external port g and h, the EMC 52 and 53 just miss one odd and the other even-numbered channels on its output ports f. Combine the channels with the help of the EMC 54, as a result, they are sent to an external port k. As the dispersion stage of the EMC 52 and 53 and two of the EMC 54 eleutherodactyline signs, it thus provides a zero or near-zero dispersion of the entire device 50.

Diagram of one embodiment of a managed optical multiplexer according to the present invention is shown in Fig.6. This is a controllable optical multiplexer 60 configuration "1×8", that is, a device for combining eight channels with spectral interval between adjacent frequency channels equal to Δν=1600 GHz.

The multiplexer is a three-stage structure of type "tree" on seven optical filters. Four optical filter (61-1)÷(61-4) the first stage of the multistage structure of its output ports connected to the two following, optical filters 62-1 and 62-2 of the second stage, which in turn are connected to its output ports with an optical filter of the EMC 63 third stage. The entire device is fabricated on the same substrate 64.

External optical conclusions made by using optical fibers. When the optical fiber 65 is used as the General output port, the optical fibers 66-1, ..., 66-8 - 8 ports, each input channel separately. The connection of optical filters all three levels, as well as their ports with an external fiber - conclusions - made fibres 67 formed on the substrate 64. The optical fibers 65, 66-1, ..., 66-8 optically aligned with the waveguides 67 with maximum efficiency.

Dynamic control of the multiplexer 60 is accomplished by adjustment of the spectral characteristics of the seven optical filter feeding device phase shift, contained in all optical filters corresponding stresses. Management is done via the controller 68, which is connected with the optical filters electric bus 69.

The design of the multiplexer is that as you move the optical signal from one level to the next level spectral spacing between channels is twice less. Optical filters (61-1)÷(61-4) in the first stage of the spectral interval between channels maximum, the optical filter 63, on the contrary, the minimum optical filters 62-1 and 62-2 used in the second stage, the spectral spacing of the intermediate. Therefore, the requirements to the characteristics used in the respective stages of the optical filters may be different. As optical filters in this example can be used in the first stage single stage of the EMC (Figb), in the second stage of two stage of the EMC (Figb) and in the third stage of multi-stage of the EMC (Figb). The input and output ports of the optical filters of the second and third stages should be connected so that the optical signal was passed in the direction from the first to the second cascade stage of the EMC 65 and 66 and two of the EMC included in the multi-stage EMC 67.

The distance ΔF between adjacent extrema in the spectral characteristics for pricheski filters in three stages of these units are the following: for single stage of the EMC (61-1)÷(61-4): Δν 61-1=Δν61-2=Δν61-3=Δν61-4=1600 GHz; for two of the EMC 62-1 and 62-2: Δν62-1=Δν62-2=800 GHz and for the multi-stage EMC 63: Δν63=400 GHz.

Accordingly, the difference ΔL of the length of the shoulders by expression (5) in the single-stage EMC 61-1 to 61-4 will be equal to ΔL61-1=ΔL61-2=ΔL61-3=ΔL61-4=250 μm, in the first cascade stage of the EMC 62-1 and 62-2 equal to the difference ΔL62-1=ΔL62-2=125 μm, in the first cascade stage of the EMC, the components of the multi-stage EMC 63, the path difference ΔL is63=62.5 μm (assuming n=1.5).

For further consideration it is advisable to introduce the concept of transfer coefficient multiplexer, similar in the sense used above when considering the EMC, but in this case related to the transmission of the optical signal from one of the input ports (66-1)÷(66-8) multiplexer on the General output port 65. Transfer coefficients of the multiplexer, which we denote as66-1+C66-8are determined by the product of the coefficients of transmission of the optical filter through which the optical signal passes before it appears at the common output 65. For example, the transmission coefficient from the input port 66-3 in the output port 65 is:

where three cofactor in the right part are the transfer coefficients of the three optical filters 61-2, 621 and 63, the upper index corresponds to the number of the optical filter, and the lower indices of the input and output ports of the optical filter.

Obviously the transfer coefficients of the multiplexer are a function of optical frequency and phase shifts {φn} and {ϕn}. For multiplexer 60 with the right infusion of phase shifts for all seven of optical filters each of the eight coefficients of transmission should have a maximum value for the carrier frequency of one of the channels, and the minimum for frequencies of other channels.

At some phase shifts {φ*n} and {ϕ*n} - phase in the first and second stages used by the EMC, the transmission coefficient from the input port 66-3 in the input port must have a value:66-33)≈1 and K66-3(ν)≈0 if ν≠ν3. The corresponding view in the phase shifts {φ*n} and {ϕ*n} there are other transfer coefficients of the demultiplexer 60, it is natural for frequencies of the other channels.

Let the input ports of the multiplexer 60 receives input signals of the eight channels of distribution channels of input ports in accordance with table 1.

Table 1
Distribution channels input ports
Input port 66-166-266-366-466-566-666-766-8
The carrier frequency of the channelν1ν5ν3ν7ν2ν6ν4ν8

When values of the phase shifts {φ*n} and {ϕ*n} the multiplexer 60 functions as a conventional multiplexer with fixed frequency channels. The single-stage EMC (61-1)÷(61-4) first-level pairwise combine the channels and guide them through their four output ports on the second level to the two-stage EMC 62-1 and 62-2. Two of the EMC 62-1 and 62-2 again unite channels and send them to the next level multistage structure. On the third level after the passage of the waves through the EMC 63 all channels will come together and arrive at a common output port 63.

Now suppose that the input ports of the multiplexer begin to receive signals, new Central channel frequencies {νi} which are all shifted by the value of δν<Δν, i.e. νii+δν. DL is to further multiplied and combine the channels with the new optical carrier according to a separate output ports, you should make changes to the phases {φ*n} and {ϕ*n} in accordance with the expression (10). For example, to switch to multiplicitive channels whose frequencies are shifted by the value of δν=50 GHz, it is necessary to change the phase shifts in accordance with table 2.

Table 2.
Phases {φn} and {ϕn} when the frequency shift channels δν=50 GHz
The EMC (61-1)÷(61-4)The EMC 62-1 and 62-2The EMC 63
1st cascadesδφ61-4÷δφ64=-π/32δφ62-1=δφ62-2=-π/16δφ63=-π/8
2nd cascadesδf-1f-1=-π/8δf=-π/4

Other option managed optical multiplexer according to the present invention may differ from the described device 60 by the number and type of optical filters. In the General case for managed optical multiplexer configuration M×1, where M is the value of row 4, 16, 32, ...2Nwhen N is 2, the number of stages in the multistage structure is N, each n-th stage when n=1, 2, ...N should be 2N-noptical filters, and the total number of optical filters, therefore, is 2n-1. For example, for multiplicitive 32 channels required number of steps increases to 5, and the number of optical filters to 31.

Tuning optical filters in each stage should be made so that the optical frequency of each of the 2Nchannel coefficients of the transmission with one of the 2Ninputs specified N-stage structure on the output would have the maximum value.

For managed optical multiplexer designed for use in DWDM system, in order to ensure, on the one hand, the required technical parameters, and on the other hand, to reduce cost, it is advisable to use in the first stages single stage of the EMC, in subsequent stages, with an average spectral interval between two channels of the EMC and, finally, in the last stages, where the input of receive channels with a small interval, the multi-stage EMC.

For managed optical multiplexer designed for CWDM systems, as optical filters you can use two or even a single stage of the EMC. Note that in the Lu reversibility of the optical characteristics of the single-stage EMC appropriate device as a whole is also reversible, that is, it can be used as a controlled multiplexer/demultiplexer.

Managed optical multiplexers can be used not only in communication systems with wavelength division multiplexing, but also in several other systems, such as in multi-channel systems, sensors, optical filtering in analog systems for various purposes.

For example, the above-described controlled optical multiplexer 60 may be used in an optical system with a fixed frequency channels, in which there may be times when the channel inputs are swapped. The desired operation can also be achieved by appropriate changes in the magnitude of phase shifts {φn} and {ϕn}. For example, if you want to inputs 66-1 and 66-2 swap channels with carrier frequencies ν1and ν5and distribution of all other channels on the input ports, you must use the device phase shift in a single stage of the EMC 61-1 to change the phase φ61-1:

φ*61-1→φ*61-1+δφ61-1where δφ61-1=±π.

The use of integrated optical technologies for manufacturing seems to be the decisive factor for controlled optical multiplexer according to the present invention have the necessary resistance to external influences, Bolshova channels, the high speed. The use of a uniform standard elements of structure in single-stage and/or two-stage and/or multi-stages EMC allows you to use automated process operations that will provide high performance and relatively low cost of manufacture multiplexers.

The use of optical filters - single stage, two stage or multistage IMTS - should be specific optical communication systems. As devices of the phase shift can be used as electro-optical and thermo-optical device, in this electro-optical device of the phase shift can guarantee extremely high speed adjustment of the spectral characteristics of the multiplexer.

The examples explain the principle of operation, characteristics and possible options for the design of the present invention. Specialists in the field of fiber-optic communication systems should be obvious that within the framework of the present invention there may be other modifications and alternatives design managed optical multiplexer according to the invention, is not beyond the scope of the claims.

Industrial applicability

The way managed multiplexing with the according to the invention with controlled optical multiplexer according to the present invention can be used in fiber-optic lines and communication systems with wavelength division multiplexing channels, including trunk lines, using DWDM technology, and in regional, urban and local communication systems using CWDM technology.

Managed optical multiplexer according to the present can be implemented using existing integrated optical technologies.

1. The way managed multiplexing channels in the fiber optic communication system using wavelength division multiplexing 2Nchannels, optical frequencies with a constant spectral interval between adjacent channels Δν can be reconstructed, in which:
(a) serves 2Nchannels, each channel separately, 2Ninputs N-stage structure of type "tree"that contains every n-th step, when n=1, 2,..., N, 2N-noptical filters having two inputs and at least one output made with the possibility of a managed realignment transmission ratios and characterized by a frequency interval between adjacent extrema in the dependency ratios of the transmission frequency Δνn=2n-1Δν, and inputs the specified N-stage structure are each of the two inputs of each optical filter of the first stage;
(b) configuring the optical filter of each stage so that the optical frequency of each of the 2Nchannel transmission ratios with the underwater of the 2 Ninputs specified N-stage structure on the output would have a maximum value;
(C) transmit the multi-channel optical signal through the N-stage structure and receive the output of the optical filter of the last stage of the multi-channel optical signal.

2. Managed optical multiplexer for use in fiber-optical networks with wavelength division multiplexing 2Nchannels, optical frequencies with a constant spectral interval between adjacent channels Δν can be reconstructed with a 2Ninput port [(66-1),..., (66-8)] and one output port (65), including:
N-stage structure (60) of type "tree"that contains every n-th step, when n=1, 2,..., N, 2N-noptical filters [(61-1),..., (61-4); (62-1), (62-2); 63]made with the possibility of a managed realignment transmission ratios, characterized in n-tier frequency interval between adjacent extrema in the dependency ratios of the transmission frequency Δνn=2N-nΔν, and having two inputs [a, b, or g, h] and at least one output [C or e, or k];
the controller (68) to manage the rebuilding of the transmission coefficients of these filters [(61-1),..., (61-4); (62-1), (62-2); 63].

3. The multiplexer according to claim 2, characterized in that the specified multi-stage structure
two inputs [a, b, or g, h] of each optical filter of the first of the stages is connected to one of the input ports [(66-1),..., (66-8)];
optical filters [(62-1), (62-2); 63] in each stage, except the first, are connected to each of the two inputs [a, b; g, h] output [C, e] one of the optical filters of the previous stage;
output [k] optical filter (63) the last stage connected to the output port (65).

4. The multiplexer according to claim 2, characterized in that the optical filters [(61-1),..., (61-4); (62-1), (62-2); 63] N-step patterns are single-stage (10), and/or two-stage (30), and/or multistage (50) unbalanced interferometers, Mach-Zehnder interferometers.

5. The multiplexer according to any one of claim 2 to 4, characterized in that to control the setting of the coefficients of transmission of optical filters [(61-1),..., (61-4); (62-1), (62-2); 63] contain electro-optical or thermo-optical devices [15; 37, 38] phase shift.

6. The multiplexer according to claim 2, characterized in that it is executed on the integrated optical technologies on a single chip.

7. The multiplexer according to claim 2, where all input ports [(66-1),..., (66-8)] and the output port (65) is performed using optical fibers.



 

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