CN115308844B - Monolithic integrated chip for multichannel all-optical signal processing and processing method thereof - Google Patents
Monolithic integrated chip for multichannel all-optical signal processing and processing method thereof Download PDFInfo
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- G02F2/00—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light
- G02F2/004—Transferring the modulation of modulated light, i.e. transferring the information from one optical carrier of a first wavelength to a second optical carrier of a second wavelength, e.g. all-optical wavelength converter
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Abstract
The invention discloses a single-chip integrated chip for multi-channel all-optical signal processing and a processing method thereof, wherein the single-chip integrated chip comprises a first semiconductor optical amplifier, a first multimode interferometer, a second semiconductor optical amplifier, a phase modulator and a second multimode interferometer which are connected through a passive optical waveguide; the first multimode interferometer, the second semiconductor optical amplifier, the phase modulator, the second multimode interferometer and the connected passive optical waveguide form a delay interferometer filter; the passive optical waveguide between the first multimode interferometer for dividing the wave and the second multimode interferometer for combining the wave forms an upper arm of a delay interferometer filter, and a lower arm of the delay interferometer filter consists of a phase modulator and a second semiconductor optical amplifier, wherein the phase modulator is connected in series with the second semiconductor optical amplifier; the upper arm and the lower arm of the delay interferometer filter are respectively connected with the first multimode interferometer and the second multimode interferometer. The invention is used for realizing the simultaneous all-optical signal processing of multiple paths of signals.
Description
Technical Field
The invention belongs to the technical field of all-optical signal processing, and particularly relates to a single-chip integrated chip for multi-channel all-optical signal processing and a processing method thereof.
Background
As the demand for communication capacity increases, the demands for information transmission capability and information processing capability of the optical communication network are also increasing. The information transmission capability develops rapidly, and the information processing of the network node is a bottleneck limiting the further improvement of the network capacity. Although the conventional electric domain signal processing technology is mature, it can perform many complex and accurate signal processing, but to perform information processing in the electric domain, it needs to undergo optical-electrical-optical conversion, so as to face limitations in bandwidth, power consumption, complexity and the like. The all-optical signal processing technology avoids the conversion of light-electricity-light, has the advantages of higher signal processing bandwidth potential, lower bit processing power consumption, convenience for photon integration and the like, and has important research significance.
The Semiconductor Optical Amplifier (SOA) has the advantages of high nonlinear coefficient, multiple nonlinear effect types, internal gain, small required input optical power, small volume, convenient integration and the like, wherein the nonlinear effects such as four-wave mixing effect, cross phase modulation, transient cross phase modulation, cross gain modulation (XGM), self-phase modulation and the like are widely used for realizing different optical signal processing functions. It should be noted that the operation mechanism of the cross-phase modulation effect in the SOA is different from that of the passive nonlinear operation medium, the phase modulation effect in the SOA is caused by refractive index modulation caused by carrier concentration change, and depends on first-order polarization of interaction of light with the operation substance, and the phase modulation in the passive operation medium is based on third-order nonlinear polarization of the operation medium. The working substance, the device structure, the manufacturing process and the common InP-based semiconductor laser in the SOA are similar, so that the optical signal processing chip based on the SOA can be realized by referring to the InP-based monolithic integration process. In addition, since the SOA has internal gain and relatively high nonlinear coefficient, the requirement on input signal power is small, but the ASE (amplified spontaneous emission) noise can degrade signal quality, and the problem that the device is heated easily due to the need of adding bias current during operation exists. In the research of all-optical signal processing based on an SOA, early researches of students at home and abroad mainly focus on discrete devices, and along with the rapid development of the optical integrated chip technology, the research center of gravity of people on all-optical signal processing is gradually shifted to a scheme based on an integrated chip so as to obtain miniaturized devices, and the practicability of the optical signal processing technology is promoted.
Research on a multi-channel all-optical signal processing integrated chip adapting to a multi-wavelength communication network is important to promote specific application of all-optical signal processing technology in the optical communication network. The existing all-optical signal processing is mostly based on discrete devices, and the aspect of integrated devices can only realize single-channel processing. Accordingly, the present inventors developed a monolithically integrated chip for multichannel all-optical signal processing, which resulted therefrom.
Disclosure of Invention
The invention aims to provide a single-chip integrated chip for multi-channel all-optical signal processing and a processing method thereof, which are used for realizing simultaneous all-optical signal processing of multi-channel signals.
In order to solve the technical problems, the technical solution of the invention is as follows:
the monolithic integrated chip for multi-channel all-optical signal processing comprises a first semiconductor optical amplifier, a first multimode interferometer, a second semiconductor optical amplifier, a phase modulator and a second multimode interferometer which are connected through a passive optical waveguide; the first multimode interferometer, the second semiconductor optical amplifier, the phase modulator, the second multimode interferometer and the connected passive optical waveguide form a delay interferometer filter; the passive optical waveguides of the first multimode interferometer for splitting and the second multimode interferometer for combining form an upper arm of a delay interferometer filter, and the lower arm of the delay interferometer filter consists of a phase modulator, a second semiconductor optical amplifier and a passive waveguide, wherein the phase modulator is connected with the second semiconductor optical amplifier in series; the upper arm and the lower arm of the delay interferometer filter are respectively connected with the first multimode interferometer and the second multimode interferometer, and the length of the first semiconductor optical amplifier in the optical path transmission direction is longer than that of the second semiconductor optical amplifier in the optical path transmission direction.
Further, the first multimode interferometer, the second semiconductor optical amplifier, the phase modulator and the second multimode interferometer are sequentially connected through the passive optical waveguide, or the first multimode interferometer, the phase modulator, the second semiconductor optical amplifier and the second multimode interferometer are sequentially connected through the passive optical waveguide.
Further, the second semiconductor optical amplifier has a length of 300 to 500 μm.
Further, a third semiconductor optical amplifier is included and is coupled to the second multimode interferometer through a passive optical waveguide.
Further, the length of the first semiconductor optical amplifier is 2000 μm, the length of the second semiconductor optical amplifier is 400 μm, and the length of the third semiconductor optical amplifier is 500 μm.
Further, the first semiconductor optical amplifier and the second semiconductor optical amplifier are active structures, the first multimode interferometer, the phase modulator, the second multimode interferometer and the connected passive optical waveguide are passive structures, and the active structures and the passive structures are monolithically integrated through a butt joint regrowth process.
A multi-channel all-optical signal processing method comprises the following steps:
coupling a plurality of paths of non-return-to-zero on-off keying code signal light and one path of pump light signals and then inputting the coupled signals into a first semiconductor optical amplifier, or coupling a plurality of paths of non-return-to-zero quadrature phase shift codes and one path of pump light signals and then inputting the coupled signals into the first semiconductor optical amplifier, wherein nonlinear cross phase modulation and cross gain modulation occur, and the frequency spectrum of the non-return-to-zero on-off keying code or the frequency spectrum of the non-return-to-zero quadrature phase shift codes is modulated and then widened;
step two, the widened frequency spectrum is subjected to wave division through a first multimode interferometer of a delay interferometer filter, and enters an upper arm and a lower arm of the delay interferometer filter respectively, the control of the channel spacing is realized by controlling the optical path difference of the upper arm and the lower arm, wherein the second semiconductor optical amplifier of the lower arm is used for amplifying, compensating the loss introduced by a phase modulator, realizing the control of the phase shift quantity and achieving the effect of detuning filtering;
the frequency spectrum of the upper arm and the frequency spectrum of the lower arm are subjected to wave combination through the second multimode interferometer, and corresponding frequency components are subjected to detuning filtering, so that a converted multi-channel return-to-zero switch key code or multi-channel return-to-zero quadrature phase shift code is obtained.
Further, the non-return-to-zero on-off key code and the non-return-to-zero quadrature phase shift code are probe light, and the optical power of the pump light is higher than that of the probe light.
In the second step, the second semiconductor optical amplifier is used for amplifying, and the loss introduced by the subsequent phase modulator is pre-compensated; or the optical signal is amplified by the phase modulator and then by the second semiconductor optical amplifier to compensate the loss introduced by the phase modulator.
And further, the method also comprises a step three, wherein the multi-channel return-to-zero switch key code or the multi-channel return-to-zero quadrature phase shift code obtained after conversion is amplified by a third semiconductor optical amplifier.
Further, in step two, the extinction ratio of the delay interferometer filter is 20dB or more.
After the scheme is adopted, as the first semiconductor optical amplifier is used for providing nonlinear interaction, the second semiconductor optical amplifier provides compensation amplification of loss, and the two multimode interferometers, the second semiconductor optical amplifier and the phase modulator jointly form a delay interferometer, so that simultaneous filtering processing of multipath signals can be realized by using the delay interferometer. The pump light and the detection light have nonlinear cross phase modulation and cross gain modulation in the first semiconductor optical amplifier, the spectrum of the detection light is widened after being modulated, simultaneous detuning filtering of multiple paths of signals is realized through the comb filter line type of the delay interferometer, a special extinction ratio is set, and corresponding frequency components are filtered, so that signals after code pattern conversion are obtained, and simultaneous processing of multiple paths of signals can be realized.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic diagram of the present invention;
FIG. 3 shows DI transmission spectra obtained when the upper arm and the lower arm take different ratios of light;
FIG. 4 is a schematic diagram of the spectral evolution of the multi-channel NRZ-OOK to RZ-OOK pattern conversion according to the present invention;
FIG. 5 is an eye diagram and waveform diagram of four-way original NRZ-OOK signals that can be simultaneously converted into four-way RZ-OOK signals;
FIG. 6 is a schematic diagram of the spectral evolution process of the conversion of the multichannel NRZ-QPSK to RZ-QPSK pattern according to the invention;
fig. 7 is a waveform diagram and eye diagram of NRZ-QPSK to RZ-OOK conversion.
Description of the reference numerals
Passive optical waveguide 1 first semiconductor optical amplifier 2 delay interferometer filter 3
First multimode interferometer 31 second semiconductor optical amplifier 32 phase modulator 33
Second multimode interferometer 34 third semiconductor optical amplifier 4
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific examples. The invention discloses a monolithic integrated chip for multichannel all-optical signal processing, which is a preferred embodiment of the invention, as shown in fig. 1, wherein a first semiconductor optical amplifier 2, a first multimode interferometer 31, a second semiconductor optical amplifier 32, a phase modulator 33 and a second multimode interferometer 34 are sequentially connected through a passive optical waveguide 1. The first multimode interferometer 31 and the second multimode interferometer 34 are connected by the passive optical waveguide 1.
Wherein the first 31, second 32, phase modulator 33 and second 34 multimode interferometers and the connected passive optical waveguide 1 form a delay interferometer filter 3 (DI for short) for implementing a multichannel simultaneous filtering process. The upper arm of the delay interferometer filter 3 is composed of a passive optical waveguide 1, and the lower arm of the delay interferometer filter is composed of the passive optical waveguide 1, a phase modulator 33 and a second semiconductor optical amplifier 32. I.e. the upper arm of the time delay interferometer filter 3 is connected to the first 31 and the second 34 multimode interferometers, respectively. The lower arm of the delay interferometer filter 3 is connected to a first multimode interferometer 31 and a second multimode interferometer 34, respectively. The control of the channel spacing can be realized by designing the optical path differences of different upper arms and lower arms, and the processing speed is determined.
A first semiconductor optical amplifier 2 for a carrier in which all optical signal interactions occur. In this embodiment, the multichannel NRZ signal is used as the probe light, the strong clock signal is used as the pump light, the two signals are input to the first semiconductor optical amplifier 2 together, and under the effect of the cross phase modulation effect in the first semiconductor optical amplifier 2, the output multichannel light carries stronger periodic phase modulation information, and the frequency spectrum is widened.
The first multimode interferometer 31, in this embodiment, is a 1×2MMI (multimode interferometer) for splitting, and after splitting, enters the upper arm and the lower arm of the DI, respectively.
A second semiconductor optical amplifier 32 for signal compensation. For adjusting the optical power of the lower arm of the delay interferometer filter 3 to compensate for the absorption introduced by the phase modulator 33, and for equalizing the power of the upper arm and the power of the lower arm of the delay interferometer filter 3 to increase the extinction ratio of the delay interferometer filter 3.
And the phase modulator 33 is used for adjusting the central wavelength of the delay interferometer filter and realizing the detuning filtering of the signal. In the present invention, the second semiconductor optical amplifier 2 and the phase modulator 33 are used, and the second semiconductor optical amplifier 32 is used to compensate the signal, so that the detuning filtering of the phase modulator 33 can achieve better effect. If the phase modulation is simply considered and the signal compensation is not considered, the effect of the detuning filter is poor.
The second multimode interferometer 34 is, in the present embodiment, a 2×1MMI (multimode interferometer) for a composite wave.
Further, the length of the first semiconductor optical amplifier 2 is longer than the length of the second semiconductor optical amplifier 32 in the optical path transmission direction. (length refers to the length of the device in the optical path transfer direction, and width perpendicular to the optical path transfer direction). The first semiconductor optical amplifier 2 is used to provide nonlinear effects, the second semiconductor optical amplifier 32 is used to amplify and compensate signals, the two amplifiers have different lengths, and the first semiconductor optical amplifier 2 is longer than the second semiconductor optical amplifier 32.
Further, in the optical path transmission direction, the ratio of the length of the first semiconductor optical amplifier to the length of the second semiconductor optical amplifier is 5:1. The invention defines a specific length ratio, which can further improve the stability of the device.
Further, there are two ways in which the phase modulator 33 and the second semiconductor optical amplifier 32 are connected in series. The first is that the upper arm is composed of passive waveguide, and the lower arm is connected with the first multimode interferometer 31, the second semiconductor optical amplifier 32, the phase modulator 33 and the second multimode interferometer 34 in sequence through the passive optical waveguide 1. That is, the second semiconductor optical amplifier 32 is used for amplifying, compensating the loss introduced by the subsequent phase modulator 33, and then the phase modulator 33 is used for changing the working condition of the phase modulator 33 to control the phase shift, thereby achieving the effect of detuning filtering.
The second is that the upper arm is composed of passive waveguide, and the lower arm is connected with the first multimode interferometer 31, the phase modulator 33, the second semiconductor optical amplifier 32 and the second multimode interferometer 34 in sequence through the passive optical waveguide 1. That is, the phase shift amount is controlled by changing the working condition of the phase modulator 33 to achieve the effect of detuning filtering by amplifying the phase signal through the phase modulator 33 and then amplifying the phase signal through the second semiconductor optical amplifier 32 to compensate the loss introduced by the phase modulator 33.
Further, the length of the second semiconductor optical amplifier 32 is 300 to 500 μm, and preferably, the length of the second semiconductor optical amplifier 32 is 400 μm. The losses of the upper arm and the lower arm of the DI should be ensured to be equal as much as possible when the DI is designed and manufactured, so that the finally manufactured DI filter has higher extinction ratio. Since the lower arm contains the phase modulator 33, additional loss is introduced, the present invention designs the second semiconductor optical amplifier 32 to compensate for the loss caused by the phase modulator 33, so that the upper and lower losses are equal. For the length of the second semiconductor optical amplifier 32, the optimal design is also required, if the length is too short, the amplification compensation effect cannot be achieved sufficiently, and if the length is too long, the device is not compact enough, so that the length interval of the optimal design is 300-500 μm.
Further, a third semiconductor optical amplifier 4 is included, and the third semiconductor optical amplifier 4 is connected to the second multimode interferometer 34 through the passive optical waveguide 1, so as to provide post amplification, so as to have a higher output and boost power, so as to facilitate subsequent application.
Further, the length of the first semiconductor optical amplifier 2 is 2000 μm, the length of the second semiconductor optical amplifier 32 is 400 μm, and the length of the third semiconductor optical amplifier 4 is 500 μm. The length of the first semiconductor optical amplifier 2 is designed to be about 2000 μm, and enough length can provide nonlinear effect intensity required by signal processing; the second semiconductor optical amplifier 32 is designed to have a length of about 400 μm, and the device is compact while the amplification compensation effect is satisfied; the length of the third semiconductor optical amplifier 4 is designed to be about 500 μm to amplify the signal-processed optical signal. The function of the device code type conversion is realized by the optimal design of superposition combination of three semiconductor optical amplifiers, and the device is an optimal collocation structure.
Further, the first semiconductor optical amplifier 2 and the second semiconductor optical amplifier 32 are active structures, the first multimode interferometer 31, the phase modulator 33, the second multimode interferometer 34 and the connected passive optical waveguide 1 are passive structures, and the active structures and the passive structures are monolithically integrated by a butt-joint regrowth process (i.e., the passive structures and the active structures are implemented on the same substrate). The process of butt regrowth is a common technique in the art and will not be described in detail herein. The optical waveguides used for connecting the active devices are all passive optical waveguides 1, including straight waveguides and curved waveguides.
The invention also provides a multi-channel all-optical signal processing method, which comprises the following steps:
coupling a plurality of paths of non-return-to-zero on-off keying code signal light and one path of pump light signals and then inputting the coupled paths of non-return-to-zero quadrature phase shift codes and one path of pump light signals into a first semiconductor optical amplifier 2, or coupling the coupled paths of non-return-to-zero quadrature phase shift codes and one path of pump light signals and then inputting the coupled paths of non-return-to-zero quadrature phase shift codes and one path of pump light signals into the first semiconductor optical amplifier 2, wherein nonlinear cross phase modulation and cross gain modulation occur, and the frequency spectrum of the non-return-to-zero on-off keying code or the frequency spectrum of the non-return-to-zero quadrature phase shift codes is modulated and then widened;
step two, the widened frequency spectrum is subjected to wave division through a first multimode interferometer 31 of the delay interferometer filter 3, enters an upper arm and a lower arm of the delay interferometer filter 3 respectively, and controls the channel spacing by controlling the optical path difference of the upper arm and the lower arm, wherein the second semiconductor optical amplifier 32 of the lower arm is used for amplifying, compensating the loss introduced by the phase modulator 33, realizing the control of the phase shift quantity and achieving the effect of detuning filtering;
the frequency spectrum of the upper arm and the frequency spectrum of the lower arm are subjected to the combination of the second multimode interferometer 34, and the corresponding frequency components are detuned and filtered, so that the converted multi-channel return-to-zero switch key code or multi-channel return-to-zero quadrature phase shift code is obtained.
Further, the non-return-to-zero on-off key code and the non-return-to-zero quadrature phase shift code are probe light, and the optical power of the pump light is higher than that of the probe light.
Further, the extinction ratio of the delay interferometer filter is greater than or equal to 20dB (i.e., ER is greater than or equal to 20 dB). The concrete calculation mode is as follows: the method comprises the steps that interference superposition of two beams of light which are transmitted in the same frequency and the same direction at the output port of a delay interferometer filter is carried out, and the two beams of light are respectively expressed as:
the result after the superposition interference is expressed as:
from the above equation, the intensity of the composite wave is expressed as:
as can be seen from the above, the output spectrum of the delay interferometer filter is comb-shaped, and the extinction ratio is expressed as:
the second semiconductor optical amplifier 32 does not simply amplify the signal, but equalizes the transmission losses of the DI upper and lower arms, so that a larger extinction ratio of the resultant vanity filter spectrum is ensured. Then, as can be seen from the above formula, when I 1 And I 2 The closer the approaching, the higher the extinction ratio of the resulting comb spectrum. The simulation results are shown in FIG. 3, and the curves with different marks correspond to I 1 And I 2 And taking transmission spectrums obtained at different spectral ratios. In order to avoid overlapping transmission spectra, so as to conveniently compare the extinction ratios among the transmission spectra, different spectral ratios take different center wavelengths so as to be staggered with each other. From the results of the simulation, it can be seen that the more unbalanced the beam split is, the smaller the extinction ratio is. Therefore, the losses of the upper arm and the lower arm are ensured to be equal as much as possible when the DI is designed and manufactured, so that the finally manufactured DI filter has moreThe extinction ratio of the invention is more than or equal to 20dB.
| Grouping | I 1 | I 2 | ER |
| First group of | 70 | 30 | 13.61 |
| Second group of | 60 | 40 | 19.91 |
| Third group of | 55 | 45 | 26.00 |
| Fourth group | 51 | 49 | 40.00 |
The invention is applicable to multi-channel non-return-to-zero switch key codes and multi-channel non-return-to-zero quadrature phase shift codes, and is described in further detail below by taking multi-channel non-return-to-zero switch key codes as examples. As shown in fig. 2, the integrated chip can be used to implement all-optical code conversion from multi-channel NRZ-OOK (non-return-to-zero on-off-key code) to RZ-OOK (return-to-zero on-off-key code), and the principle framework is as shown in fig. 2: firstly, an original multi-path NRZ-OOK optical signal and a path of pumped clock optical signal are generated, and then the signals are coupled and input into an integrated chip, so that in order to obtain a better code pattern conversion result, the optical power of the pump light is required to be higher, the optical power of the detection light is relatively lower, the higher pump light power can realize a stronger modulation effect, and the lower detection light power is selected to reduce crosstalk between different channels. The pump light and the detection light are subjected to nonlinear cross-phase modulation and cross-gain modulation in an SOA, the spectrum of the detection light is modulated and then broadened, the simultaneous detuning filtering of multipath signals is realized through a DI comb filter, and corresponding frequency components are filtered, so that the converted multipath RZ-OOK is obtained. The principle is illustrated in connection with spectral evolution as shown in fig. 4.
The invention can realize the multi-path simultaneous all-optical signal processing, and as shown in figure 5, 4 paths of original NRZ-OOK signals can be simultaneously converted into 4 paths of RZ-OOK signals after passing through the structure; wherein, in the left column of fig. 5, the eye pattern before the odd-numbered behavior is converted, and the eye pattern after the even-numbered behavior is converted; the waveforms before the odd rows of the right column of fig. 5 are converted, and the waveforms after the even rows are converted.
Of course, the invention can also be used for code pattern conversion of multi-path non-return-to-zero quadrature phase shift coding, and the conversion principle from multi-channel all-optical NRZ-QPSK to RZ-QPSK based on an SOA cascade DI filter monolithic integrated chip is similar to the conversion principle from NRZ-OOK to RZ-OOK, and the specific principle is shown in figure 6. The low-power multichannel NRZ-QPSK detection light and the strong pumping RZ clock light are simultaneously input into the SOA, and the spectrum of the output detection light carries strong periodic modulation information due to the effect of cross phase modulation effect in the SOA, so that the output spectrum is correspondingly widened. Subsequently, the simultaneous filtering of the multiple channels is realized through a DI filter, and through proper detuning, the DI filter can filter out modulation information generated by the cross-phase modulation effect, so as to obtain a converted multiple-channel RZ-QPSK signal.
Since QPSK belongs to an advanced modulation format, specific code stream information can be obtained only after demodulation by using a modulation format analyzer, in order to more intuitively show the correctness of the code pattern conversion result, the waveform diagrams before and after demodulation and the eye diagram of QPSK used in the analog process are shown in fig. 7, wherein (a) and (b) in fig. 7 are the waveform diagrams and the eye diagram of NRZ-QPSK input, and (c) and (d) in fig. 7 are the waveform diagrams and the eye diagram of RZ-QPSK converted, and the conversion from NRZ to RZ can be seen from the eye diagram before demodulation, but specific code stream information cannot be seen. Since the QPSK signal is formed by modulating and combining two OOK signals, two OOK signals of u and v paths are obtained after demodulation, wherein fig. 7 (e) and (f) are waveform diagrams and eye diagrams of the u original signals inputted, fig. 7 (g) and (h) are waveform diagrams and eye diagrams of the u original signals outputted after demodulation, fig. 7 (i) and (j) are waveform diagrams and eye diagrams of the v original signals inputted, and fig. 7 (k) and (l) are waveform diagrams and eye diagrams of the v signals outputted after demodulation. By comparing the waveform diagrams of the u-path and the v-path before and after the code pattern conversion, the code stream information before and after the conversion is one-to-one correspondence, and the correctness of the code pattern conversion is proved. Because the QPSK power change is small, the crosstalk between different channels is relatively small, 4 paths of signals obtained after conversion are relatively uniform, and the code streams before and after conversion are in one-to-one correspondence, so that only the waveform diagram and the eye diagram before and after conversion of the first channel are given in fig. 7, and the results of the other 3 paths of signals are similar.
While the invention has been described with respect to the preferred embodiments, the invention is not limited thereto, and modifications, variations and substitutions can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (11)
1. A monolithic integrated chip for multichannel all-optical signal processing, its characterized in that: the system comprises a first semiconductor optical amplifier, a first multimode interferometer, a second semiconductor optical amplifier, a phase modulator and a second multimode interferometer which are connected through a passive optical waveguide; the first multimode interferometer, the second semiconductor optical amplifier, the phase modulator, the second multimode interferometer and the connected passive optical waveguide form a delay interferometer filter; the passive optical waveguides of the first multimode interferometer for splitting and the second multimode interferometer for combining form an upper arm of a delay interferometer filter, and the lower arm of the delay interferometer filter consists of a phase modulator, a second semiconductor optical amplifier and a passive waveguide, wherein the phase modulator is connected with the second semiconductor optical amplifier in series; the length of the upper arm and the lower arm of the delay interferometer filter, which are respectively connected with the first multimode interferometer and the second multimode interferometer, in the optical path transmission direction of the first semiconductor optical amplifier is larger than that of the second semiconductor optical amplifier in the optical path transmission direction.
2. The monolithically integrated chip for multichannel all-optical signal processing of claim 1, wherein: the phase modulator and the second semiconductor optical amplifier are connected in series in the following manner: the first multimode interferometer, the second semiconductor optical amplifier, the phase modulator and the second multimode interferometer are sequentially connected through the passive optical waveguide, or the first multimode interferometer, the phase modulator, the second semiconductor optical amplifier and the second multimode interferometer are sequentially connected through the passive optical waveguide.
3. The monolithically integrated chip for multichannel all-optical signal processing of claim 1, wherein: the second semiconductor optical amplifier has a length of 300 to 500 μm.
4. The monolithically integrated chip for multichannel all-optical signal processing of claim 1, wherein: the optical fiber also comprises a third semiconductor optical amplifier which is connected with the second multimode interferometer through a passive optical waveguide.
5. The monolithically integrated chip for multichannel all-optical signal processing of claim 4, wherein: the first semiconductor optical amplifier has a length of 2000 μm, the second semiconductor optical amplifier has a length of 400 μm, and the third semiconductor optical amplifier has a length of 500 μm.
6. The monolithically integrated chip for multichannel all-optical signal processing of claim 1, wherein: the first semiconductor optical amplifier and the second semiconductor optical amplifier are active structures, the first multimode interferometer, the phase modulator, the second multimode interferometer and the connected passive optical waveguide are passive structures, and the active structures and the passive structures are subjected to single-chip integration through a butt joint regrowth process.
7. A method for multi-channel all-optical signal processing using the monolithically integrated chip of claim 1, wherein: the method comprises the following steps:
coupling a plurality of paths of non-return-to-zero on-off keying code signal light and one path of pump light signals and then inputting the coupled signals into a first semiconductor optical amplifier, or coupling a plurality of paths of non-return-to-zero quadrature phase shift codes and one path of pump light signals and then inputting the coupled signals into the first semiconductor optical amplifier, wherein nonlinear cross phase modulation and cross gain modulation occur, and the frequency spectrum of the non-return-to-zero on-off keying code or the frequency spectrum of the non-return-to-zero quadrature phase shift codes is modulated and then widened;
step two, the widened frequency spectrum is subjected to wave division through a first multimode interferometer of a delay interferometer filter, and enters an upper arm and a lower arm of the delay interferometer filter respectively, the control of the channel spacing is realized by controlling the optical path difference of the upper arm and the lower arm, wherein the second semiconductor optical amplifier of the lower arm is used for amplifying, compensating the loss introduced by a phase modulator, realizing the control of the phase shift quantity and achieving the effect of detuning filtering;
the frequency spectrum of the upper arm and the frequency spectrum of the lower arm are subjected to wave combination through the second multimode interferometer, and corresponding frequency components are subjected to detuning filtering, so that a converted multi-channel return-to-zero switch key code or multi-channel return-to-zero quadrature phase shift code is obtained.
8. The multi-channel all-optical signal processing method according to claim 7, wherein: the non-return-to-zero on-off key code and the non-return-to-zero quadrature phase shift code are probe light, and the optical power of the pump light is higher than that of the probe light.
9. The multi-channel all-optical signal processing method according to claim 7, wherein: in the second step, the second semiconductor optical amplifier is used for amplifying, and the loss introduced by the subsequent phase modulator is pre-compensated; or the optical signal is amplified by the phase modulator and then by the second semiconductor optical amplifier to compensate the loss introduced by the phase modulator.
10. The multi-channel all-optical signal processing method according to claim 7, wherein: and step three, the converted multi-channel return-to-zero switch key code or multi-channel return-to-zero quadrature phase shift code is amplified by a third semiconductor optical amplifier.
11. The multi-channel all-optical signal processing method according to claim 7, wherein: in the second step, the extinction ratio of the delay interferometer filter is greater than or equal to 20dB.
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Effective date of registration: 20231208 Address after: No. 2, Lianshan Industrial Zone, Gushan Village, Shijing Town, Nan'an City, Quanzhou City, Fujian Province, 362343 Patentee after: Quanzhou San'an Optical Communication Technology Co.,Ltd. Address before: 361100 No. 753-799, Min'an Avenue, Hongtang Town, Tong'an District, Xiamen City, Fujian Province Patentee before: XIAMEN SANAN INTEGRATED CIRCUIT Co.,Ltd. |