ES2391110B1 - OPTICAL DEVICE FOR LOGIC SIGNAL TREATMENT - Google Patents

Abstract

Optical device for the treatment of logical signals. # Optical device for the treatment of signals that allows the implementation of N-bit logic functions by using at least one semiconductor optical amplifier (16) adapted to receive a plurality of optical data signals (SOD_1. .. SOD_N) and an optical test signal (SOP). By cross modulation gain, an output signal (SOR) is generated that is a function of the data signals (SOD_1? SOD _N). Logic functions can be electronically or optically programmable.

Description

OPTICAL DEVICE FOR LOGICAL SIGNAL TREATMENT

FIELD OF THE INVENTION

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The present invention applies to the field of optical communications and more specifically, to all-optical signal processing.

BACKGROUND OF THE INVENTION

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2-bit logic gate implementations using semiconductor optical amplifiers are known.

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US 6,930,826 B2 describes the implementation of a two-bit XOR logic gate using cross gain modulation in a semiconductor optical amplifier.

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US 7,123,4047 B2 describes the implementation of a two-bit NOR logic gate using cross gain modulation in a semiconductor optical amplifier. US 7,248,400 B2 describes the implementation of a two-bit NANO logic gate using cross gain modulation in a semiconductor optical amplifier and optical couplers.

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However, these implementations perform a fixed operation on two bit streams.

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On the other hand, WO 2007/039152 describes how to obtain different logical functions, such as NOR, NOT, XOR, ANO or OR using only optical signals. The described device comprises a single semiconductor optical amplifier and a series of optical filters that allow selecting different frequency components generated by several non-linear effects.

in the semiconductor optical amplifier. This invention raises the possibility of configuring the optical output as a selection of one of the aforementioned logical operations, but does not contemplate all the possibilities of logical function between two bits, and therefore does not allow free programming of the output.

There are also known implementations of logic on multiple bits in the field of electronics, by means of logical memories.

US 2006/097752 describes an architecture to build a multiplexer based on logical tables, where the multiplexer is built by connecting a series of cascade stages. Each stage is formed by a device that has data lines and selection lines as inputs, and an output corresponding to the line selected by the selection lines.

US 6,026,227 describes how to group and interconnect the different logical cells that constitute an FPGA, dividing the matrix of logical cells into blocks, each of which has a set of local bus lines.

WO 96/42141 describes an FPGA that includes SRAM memory cells, each of which has a match configured so that read and write signals are sent through the data connection. Thus, the FPGA includes only a decoder to control the doors connected to the memory cells.

Therefore, the need for programmable logic on multiple bits executed in the optical domain still exists in the state of the art.

SUMMARY OF THE INVENTION

The present invention solves the problems described above by means of an optical device for the treatment of logic signals that allows to implement a logic function, electronically programmable, on a set of optical data signals modulated with information (for example binary). The optical device of the invention comprises the following elements: an optical coupling means, an optical semiconductor amplifier and an optical filter. Each of them is described in more detail below.

1) An optical coupling means

The optical coupling means serves to couple a set of optical data signals to each other and to an optical test signal. In principle, the coupling means can be constituted in any way known in the art, although in a preferred embodiment of the invention it is implemented by couplers, and more specifically by a first coupler, which combines the set of optical data signals, whose Output is combined with the optical test signal by a second coupler.

According to a preferred embodiment, the optical device of the invention further comprises phase controllers arranged before the input of the optical data signals and the optical test signal to the optical coupling means. The phase controllers serve to control the relative phase of these signals so that they can interfere constructively when coupled.

2) A semiconductor optical amplifier (AOS)

The AOS, which features cross gain modulation (MGC), is connected to the above optical coupling means to receive as input the result of the combination of the optical data signals and the optical test signal. The AOS output is an optical signal at the frequency of the test signal and whose value is a

logical function of optical data signals.

In addition, the AOS receives an activation input that serves to

activate a positive or negative response to a certain combination of bits

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in the data signals. This activation signal can be of two types:

-An electrical activation signal that is introduced by an input

AOS power, turning it on or off.

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-An optical activation signal, coupled to the input itself

AOS optics, and whose optical power is equal to or greater than the power

average of the combined optical data signals constitute the

AOS entrance. In this way, if the optical activation signal is

activated, suppresses the AOS output signal regardless of

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content of the input signal to the AOS.

In both cases, the activation signal is preferably a

modulated signal, so that the determination of the output value in

function of data signals (i.e. device programming),

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It is done dynamically.

3)

An optical filter

The optical filter receives the output signal from the AOS and eliminates all

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spurious signals that do not correspond to the frequency of the optical signal

test, keeping the result signal of the logical function. Be

thus avoid the use of optical circulators, a difficult component

manufacturing in photonic integrated circuits, as well as reducing noise

spontaneous optic generated by the AOS, improving the signal to

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   noise.

Finally, the optical device of the invention preferably

It also includes an additional phase controller located at the filter outlet

additional optical

Thus, it is possible to combine several of the optical devices of the invention to implement a lookup table (Look-Up-Table, or LUT). According to a preferred embodiment, the reference table according to the present invention comprises:

a) Optical input means, which receive optical signals of input data and return to the output those same optical signals of input data, as well as their denials, at a desired frequency. This ensures that the optical signals of the input data do not interfere with each other and can be eliminated by optical filtering.

b) A set of optical signal splitters, which receive the optical input signals and their denials from the optical input means and generate all their possible combinations.

e) A set of optical devices according to the invention, each of which receives as input a different combination of the optical signals of input data and its denials and provides as an output a logical function thereof.

More specifically, for a number N of optical signals of input data, the reference table comprises 2N optical devices according to the invention. Thus, the input signals of each optical device of the invention are all possible logical combinations of the optical data input signals and their denials (i.e., for two inputs A and B, the 2N inputs = 4 devices of the invention will be AB, AB, AB and AB respectively, where the underlining

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represents the logical denial of the signal). Thus, for each combination of values of the optical signals of input data, only one of the devices of the invention emits a resulting optical signal with a positive value (of course, regardless of the effect of AOS programming corresponding with the activation signals).

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Additionally, the optical query table preferably comprises a coupler, which constructively combines the plurality of optical signals resulting from the 2N devices according to the invention to obtain a final resulting optical signal that contains any logical function selected according to the established electrical or optical programming.

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Preferably, the input data signals are modulated with a zero-return modulation, so that the impact of non-linear amplification is minimized by separating the bits by a guard band at zero or very low optical power level with respect to the maximum pulse level

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Preferably, the optical test signal is amplitude and / or phase modulated with auxiliary data for later stages.

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Finally, according to another preferred embodiment, the final resulting optical signal is used as the optical signal of input data of the same device by means of feedback or of a second concatenated device. BRIEF DESCRIPTION OF THE FIGURES

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Figure 1 shows a particular embodiment of the optical device of the invention, as well as the signals involved in its operation.

Figure 2 presents a schematic of the temporal behavior of some signals of the optical device of Figure 1.

Figure 3 shows some signals in Figure 1.

frequency behavior scheme of

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Figure 4 shows a diagram of a reference table using several four optical devices according to the invention.

Figure 5 shows a particular embodiment of optical input means used in the reference table of Figure 4.

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DETAILED DESCRIPTION OF THE INVENTION

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Figure 1 shows an embodiment of the optical device (1 O) of the invention, which provides a resulting optical signal (SOR) whose data constitutes a logical NOR function of N optical data signals (SOD_1 ... SOD_N), and whose Wavelength is determined by an optical test signal (SOP).

2 or 25 3 or

   The N optical data signals, as well as the optical test signal are properly synchronized using phase controllers (11). Said controllers, in the case of presenting at least two of the optical data signals (SOD_1 ... SOD_N) on the same frequency, have the function of adjusting the degree of interference of said signals when coupled by means of a first coupler Nx1 (12 ). A second 2x1 coupler (13) additionally couples the optical test signal (SOP). Next, the N optical data signals (SOD_1 ... SOD_N) and the optical test signal (SOP), conveniently set in phase, enter a semiconductor optical amplifier (14), in which they interact by gain modulation crusade. The activation or shutdown of this logical operation is controlled in this example, by an electronic control signal (SEC).

Next, the output of the AOS (14) passes through an optical filter 15 that

allows you to select only the signal present in the signal frequency

test optics (SOP), thus eliminating any residue from the optical signals

data (SOD_1 ... SOD_N) and reducing optical noise from AOS

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(14) present in the resulting optical signal (SOR).

Finally, a phase controller (16) serves to synchronize the signal

resulting optics (SOR) with possible later stages.

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The operation of the device of the invention, therefore, can

interpreted as a logical NOR function over the N optical data signals

(SOD_1 ... SOD_N). If the power of the optical data signals is sufficient,

only one of them in a logical '1' state is capable of suppressing the optical signal of

test (SOP). By logical equivalence, that function can also be expressed

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as an ANO of the denied data optical signals (SOD_1 ...

SOD_N). That is, only in the bit period in which no optical signal from

data carry power, that is, all carry a logical 'O', there will be power, that is

a logical '1' in the resulting optical signal (SOR).

2nd

Figure 2 shows the temporal behavior of the signals

involved in the device of figure 1 for a case of N = 2 bits in which

the data is modulated in intensity with zero return. The optical signal of

test (SOP), is in this case a pulse train. The data signals SOD_1 and

SOD_2, are added constructively in the coupler (12), which in this example

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It is a 2x1 coupler. As a result, the sum signal contains a triple

level. Both in cases where SOD_1 and SOD_2 are simultaneously '1', in

in which case the signal behind the coupler (12) is maximum, or only one of them is '1'

in a bit period, the optical test signal (SOP) is suppressed by effect

of cross gain modulation. It is usual to have a small

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residue of the suppressed signal, which must be kept low enough to

avoid further deterioration of the signal. For this, the use of AOS is appropriate

   (14) with high non-linear efficiency and constant gain recovery at

less than half the bit rate used.

Figure 3 shows the frequency behavior of the signals

involved in the optical device of figure 1 for a case of N = 2 bits in the

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that the data is modulated in intensity with zero return. Optical signal

test (SOP) is identified as a harmonic signal, while the two

optical data signals (SOD_1 and SOD_2) have a spectral distribution in

sine shape. After the AOS (14), the optical data signals (SOD_1 and SOD_2)

they are amplified, while the optical test signal (SOP), in addition to

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being amplified, it is widened due to cross gain modulation.

After the optical filter (15), the resulting optical signal (SOR) prevails

Spectral content in the wavelength of the optical test signal (SOP).

While the signals present in other wavelengths are seen

strongly attenuated.

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Figure 4 presents an example of implementation of a table of

two bit query. Development will be apparent to an expert in the field

of an implementation of a programmable logic function of a number

higher bit First, each optical signal of input data

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(SODE_1, SODE_2), is converted into an optical signal of denied data

(SODN), which contains the denial of the data present in the SODE in the

wavelength of the auxiliary denial signal (SAN), and an optical signal of

adapted data (SODA), which contains the same data as SODE but in

the wavelength of the adaptive auxiliary signal (SAA). This operation is

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performed using the input means (20) represented in Figure 5.

Specifically, in the input means (20) the optical data signal

input (SODE) is combined with the auxiliary signal denier (SAN) in a

2x1 optical coupler (22), prior adjustment of its phases for synchronization of

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clock using phase controllers (21). These signals enter a

semiconductor optical amplifier (23) in which, due to the modulation of

   cross gain, optical signal data input data (SODE) is

replicates denied on the wavelength of the auxiliary denial signal

(SAINT). After an optical filter (24), only the components in the length of

Auxiliary denial signal (SAN) wave prevail, being divided

via a 1 x 2 coupler (25), taking one of its outputs as a signal

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data optics denied (SODN) and the other, prior to phase control (21), is

coupled via a 2x1 coupler (26) to an adaptive auxiliary signal

(SAA), also controlled in phase (21). The output signal of the coupler is

introduced into a semiconductor optical amplifier (27) in which, by effect

of the cross gain modulation are obtained in the wavelength of the

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auxiliary adaptation signal (SAA), the binary data present in the signal

input data optics (SODE), these being the only ones present after

filter unwanted frequency components using an optical filter (28)

and thus obtaining the frequency adapted optical data signal (SODA).

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This first stage carried out by the input means (20) serves

to generate the signals to be used in the later stages and give them the

necessary features. The minimum requirement of these signals is to be in

different frequency of the optical test signal (SOP) so that it can be

removed by optical filtering. Once the signals are generated, they are

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divide by couplers 1 x2 (32), to later enter

two by two in optical devices (1 O) according to the invention, covering all

combinations except in which the SODN and the SODA come from a

SODE itself, thus obtaining all the signal combinations of

input and input signals denied. In said optical devices (1 O)

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according to the invention, if the respective electronic control signal (SEC) is

activated, a logical '1' is obtained as the resulting optical signal (SOR) always

that the optical input signals simultaneously contain a logical 'O'.

The 4 resulting optical signals (SOR) are combined by a coupler

4x1, resulting in a final resulting optical signal (SORF). The logical function

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   contained in said SORF can be expressed according to the following table:

SODE 1

SODE 2 SORF

or

or

SEC 4

or

one SEC 3

one

or SEC 2

one

one

SEC 1

So,

he set of electronic control signals (SEC_1 ...

SEC_4) configure any N bit function (in this example 2).

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In another preferred implementation, the electronic control signal (SEC)

it can be replaced by an optical control signal (SOC) that, if activated,

suppresses the resulting optical signal (SOR) regardless of the content of the

Other signals due to cross gain modulation itself. For

this, the optical power of the optical control signal (SOC) when active

1st

is greater than the sum of the powers of the data signals.

By last,

be contemplates the possibility of using is signal optics

final result

(SORF) how optical input data signal (SODE) in

later stages

made in waterfall, O well in he own device

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creating feedback, to perform operations on different bits of a

Same data flow. In these cases,

be contemplates that the optical signal of

proof

(SOP) contain data modulated in phase, no affected by the

modulation

from gain crusade, that allow to transmit information

accessory.

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Claims (8)

1. Optical device (1 O) for processing logical signals characterized in that it comprises:

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an optical coupling means, which couples a set of optical data signals (SOD_1 ... SOD_N) and an optical test signal (SOP);

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a semiconductor optical amplifier (14), which receives as input

1 or the combination of the optical data signals (SOD_1 ... SOD_N) and the optical test signal (SOP), which interact by cross-gain modulation, and output a resulting optical signal (SOR) at the frequency of the test signal (SOP), said resulting optical signal (SOR) being a logical function of the optical data signals (SOD_1 ... SOD_N); Y 15 -a filter (15) that filters the output signal (SOR) around the frequency of the test signal (SOP). 2. Optical device (1 O) according to claim 1, wherein the medium 2 or optical coupling comprises a first coupler (12) that combines the optical data signals (SOD_1 ... SOD_N), whose output is combined with the optical test signal (SOP) by a second coupler (13). 3. Optical device (1 O) according to any of the claims 2 5 above, which also includes phase controllers (11) that establish a temporal coherence of the data signals (SOD_1 ... SOD_N). 4. Optical device (1 O) according to any of the preceding claims, 3 or where the semiconductor optical amplifier (14) is activated by an electrical activation signal (SEC) that determines the result of the logical function of the resulting optical signal (SOR).

5.

Optical device (1 O) according to any of claims 1-3 wherein the semiconductor optical amplifier (14) is activated by an optical control signal (SOC) that determines the result of the logical function of the resulting optical signal (SOR) .

6.

Optical device (1 O) according to any one of claims 4 or 5, wherein the electrical control signal (SEC) and / or the optical control signal (SOC) have a modulation that dynamically determines the result of the logic function of the resulting optical signal (SOR).

7.

Optical device (1 O) according to any of the preceding claims, further comprising an additional phase controller (16) arranged at the output of the optical filter (15).

15 8. Optical query table, comprising:

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N optical input means (20), which receive optical signals of input data (SODE_1, .. SODE_N) and return said optical signals of input data (SODE_1, .. SODE_N) and their denials (SODN_1, ..

2 or SODN_N) at a desired frequency;

-

2N optical signal dividers, which receive the optical signals of input data (SODE_1, .. SODE_N) and their denials (SODN_1, .. SODN_N) and generate all their possible combinations; Y

25 -2N optical devices (1 O) according to any of claims 1-8, which receive the combinations of the optical input data signals (SODE_1, .. SODE_N) and their denials (SODN_1, .. SODN_N) and provide as Output a logical function of them.
9. Optical reference table according to claim 8, further comprising a coupler (33) that constructively combines the signals

resulting optical (SOR_1 ... SOR_N) of the 2N optical devices (1 O) to obtain a final resulting optical signal (SORF) containing a logical function selected from the optical input data signals (SODE_1, .. SODE_N).

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1O. Optical query table according to any of claims 8-9 wherein the optical input data signals (SODE_1 ... SODE_N) are modulated with a zero return modulation.

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11. Optical query table according to any of claims 8-1 OR wherein the optical test signal (SOP) is amplitude and / or phase modulated with auxiliary data for later stages.

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   12. Optical query table according to any of claims 8-11 wherein the final resulting optical signal (SORF) is used as the optical input data signal (SODE) of the same device by means of feedback or of a second concatenated device.