CN110635851A - Modulator driving method and system suitable for quantum state random optical signal - Google Patents
Modulator driving method and system suitable for quantum state random optical signal Download PDFInfo
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Abstract
The invention provides a modulator driving method and a system suitable for quantum state random optical signals, wherein the system comprises the following steps: an input terminal group comprising at least two input terminals; each input end is used for inputting an aligned random input signal; the adjustable gain amplifier group comprises at least two adjustable gain amplifiers; the broadband resistance network terminal is used for combining the voltage signals output by the adjustable gain amplifiers and outputting combined signals; the broadband amplifier is used for amplifying the combined signal to the amplitude required by modulation to form a driving signal; the signal ground port of the modulator is connected with a power supply, a power supply signal is loaded to the broadband amplifier through the radio frequency port after being processed by the modulator, and the modulator receives a driving signal output by the broadband amplifier from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal. The invention can satisfy the broadband drive of 0 Hz-10 GHz level, and effectively solves the substrate jitter problem.
Description
Technical Field
The invention relates to the technical field of quantum communication, in particular to the technical field of quantum signal driving, and specifically relates to a modulator driving method and system suitable for quantum state random optical signals.
Background
A modulator driving system applicable to a quantum state random optical signal in the prior art scheme is shown in fig. 1, and includes a quantum state random input signal, an ac coupling capacitor, an adjustable gain amplifier, a broadband resistor network, a broadband amplifier, an inductor or Bais _ T, and a modulator.
The AC coupling capacitor functions to pass the AC component of the input signal, but not the DC component; the adjustable gain amplifier has the function of amplifying the received signal, and the gain is adjustable to adjust the voltage value finally output to the modulator; the broadband resistance network has the function of combining and outputting two paths of signals; the function of the broadband amplifier is to amplify the input signal; the inductor or the Bais _ T has the functions of enabling a power supply to supply power to the broadband amplifier and enabling signals not to be shunted towards the power supply; the modulator is controlled to modulate the passing optical signal after receiving the RF signal, and may be a phase modulator or an intensity modulator.
In the field of quantum communication, four levels of random pulse signals of 0, 1/2, 1, 3/2 are commonly used to modulate a modulator, in the existing scheme, an adjustable gain amplifier of one channel can be configured to make the amplitude of an output signal of the adjustable gain amplifier be half of that of the other channel, and then the adjustable gain amplifier is subjected to superposition output in a rear-end broadband resistor network, so that after high-speed random optical signals are loaded on two input ends, four levels of driving signals of 0, 1/2, 1, 3/2 can be superposed to drive the modulator.
The existing scheme adopts a broadband matching design, can meet the requirement of broadband amplification of 100 KHz-10 GHz level, and can control the deterioration amount of signal quality within a certain range by using a non-broadband matching design because the low frequency reaches 100KHz, and can be used in a modulator system with lower signal quality requirement. However, in a system with a high signal quality requirement, the error rate of the system is increased and the performance of the system is greatly reduced due to signal quality problems such as substrate jitter and amplitude jitter. Moreover, since the spectral components of the quantum state random optical signal are very wide, the low end is close to 0Hz (i.e. direct current), and the high end is several times of the system frequency, if the signal is amplified without distortion, the driving scheme covers the requirements of the low end and the high end. In practical applications, the high side is easier to implement and the low side is more difficult to implement, and the low side signal is suppressed due to the presence of the ac coupling capacitor and inductor or Bais _ T. And the low frequency of the drive circuit broadband is not low enough, which can cause signal distortion after random optical signal amplification and signal quality deterioration.
Disclosure of Invention
In view of the above drawbacks of the prior art, an object of the present invention is to provide a method and a system for driving a modulator suitable for a quantum state random optical signal, so as to solve the problems of substrate jitter and poor signal quality caused by insufficient low broadband frequency existing in the conventional modulator driving system suitable for a quantum state random optical signal.
To achieve the above and other related objects, the present invention provides a modulator driving system suitable for a quantum state random optical signal, comprising: an input terminal group comprising at least two input terminals; each input end is respectively used for inputting aligned random input signals; the adjustable gain amplifier group comprises at least two adjustable gain amplifiers; each adjustable gain amplifier is correspondingly connected with the input end one by one and used for amplifying the corresponding random input signal, adjusting the gain and outputting the adjusted voltage signal; the broadband resistance network terminal is in communication connection with the adjustable gain amplifier group and is used for combining the voltage signals output by the adjustable gain amplifiers and outputting combined signals; the broadband amplifier is in communication connection with the broadband resistance network terminal and is used for amplifying the combined signal to an amplitude required by modulation to form a driving signal; a modulator; a signal ground port of the modulator is connected with a power supply, and a power supply signal is processed by the modulator and then loaded onto the broadband amplifier through a radio frequency port; the modulator receives the driving signal from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal.
In an embodiment of the invention, a modulation amount of the quantum state random optical signal by the modulator is a modulation amount corresponding to a difference between a voltage of the radio frequency port and a voltage of the signal ground port.
In an embodiment of the present invention, when the digital signal is in the unmodulated operating state, the random encoded signal output by the modulator is a high level signal, and a difference between a voltage of the radio frequency port and a voltage of the signal ground port is 0; when the modulator is in a modulation working state, the random coding signal output by the modulator is a low-level signal, and the voltage of the radio frequency port and the voltage of the signal ground port have a difference value.
In an embodiment of the present invention, the adjustable gain amplifier is an adjustable gain amplifier capable of adapting to a dc input/output signal; the broadband amplifier is a broadband amplifier which can be adapted to direct current input and output signals.
In an embodiment of the present invention, the input end and the output end of the adjustable gain amplifier are respectively connected with an ac coupling capacitor, and/or the input end and the output end of the broadband amplifier are respectively connected with an ac coupling capacitor.
In an embodiment of the present invention, the input terminal set includes two input terminals for inputting two aligned random input signals; the adjustable gain amplifier group comprises two adjustable gain amplifiers; and the amplitude of the output signal of one adjustable gain amplifier is half of that of the output signal of the other adjustable gain amplifier.
In an embodiment of the present invention, the input terminal set includes three input terminals for inputting three aligned random input signals; the adjustable gain amplifier group comprises three adjustable gain amplifiers; the output signal amplitudes of the three adjustable gain amplifiers are 1/2, 1 and 3/2 respectively.
The embodiment of the present invention further provides a modulator driving method suitable for a quantum state random optical signal, where the modulator driving method suitable for a quantum state random optical signal includes: inputting at least two paths of aligned random input signals; amplifying the input signal through at least two adjustable gain amplifiers, adjusting the gain and outputting an adjusted voltage signal; combining the output voltage signals through a broadband resistance network terminal and outputting combined signals; amplifying the combined signal to an amplitude required by modulation through a broadband amplifier to form a driving signal; and connecting a signal ground port of a modulator with a power supply, processing a power supply signal by the modulator, and then loading the power supply signal to the broadband amplifier through a radio frequency port, wherein the modulator receives the driving signal output by the broadband amplifier from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal.
In an embodiment of the invention, a modulation amount of the quantum state random optical signal by the modulator is a modulation amount corresponding to a difference between a voltage of the radio frequency port and a voltage of the signal ground port.
In an embodiment of the present invention, when the digital signal is in the unmodulated operating state, the random encoding signal of the modulator outputs a high level signal, and a difference between the voltage of the radio frequency port and the voltage of the signal ground port is 0; when the modulator is in a modulation working state, the random coding signal output by the modulator is a low-level signal, and the voltage of the radio frequency port and the voltage of the signal ground port have a difference value.
In an embodiment of the invention, the adjustable gain amplifier is an adjustable gain amplifier capable of adapting to the dc input/output signal and/or the wideband amplifier is a wideband amplifier capable of adapting to the dc input/output signal.
In an embodiment of the present invention, the input end and the output end of the adjustable gain amplifier are respectively connected with an ac coupling capacitor, and/or the input end and the output end of the broadband amplifier are respectively connected with an ac coupling capacitor.
In an embodiment of the present invention, two paths of aligned random input signals are input, and there are two adjustable gain amplifiers; and the amplitude of the output signal of one adjustable gain amplifier is half of that of the output signal of the other adjustable gain amplifier.
In an embodiment of the present invention, three aligned random input signals are input, and the number of the adjustable gain amplifiers is three; the output signal amplitudes of the three adjustable gain amplifiers are 1/2, 1 and 3/2 respectively.
In an embodiment of the present invention, when the modulator is in an unmodulated operating state, the random encoding signal of the modulator outputs a high level signal, and a difference between the voltage of the rf port and the voltage of the signal ground port is 0; when the modulator is in a modulation working state, the random coding signal of the modulator outputs a low-level signal, a difference value exists between the voltage of the radio frequency port and the voltage of the signal ground port, and the modulation amount of the modulator on the quantum-state random optical signal is a modulation amount corresponding to the difference value between the voltage of the radio frequency port and the voltage of the signal ground port.
As described above, the modulator driving method and system suitable for the quantum state random optical signal according to the present invention have the following advantages:
according to the technical scheme, alternating current coupling capacitors and inductors or Bais _ T are not used, direct current matching is achieved in all-channel design, broadband driving from 0Hz (direct current) to more than 10GHz can be achieved theoretically, broadband driving from 0Hz (direct current) to 10GHz can be achieved (the upper frequency limit of the scheme is not limited theoretically), the problem of substrate jitter of the existing driving circuit is effectively solved, the signal quality of driving signals is greatly optimized, the driving signals can be used in a system with high signal quality requirements, and the performance of the system is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic block diagram of a prior art modulator driving system suitable for quantum state random optical signals.
Fig. 2 is a schematic block diagram of a modulator dynamic system suitable for quantum state random optical signals according to the present invention.
Fig. 3 is a schematic block diagram of an embodiment of a driving system of a modulator suitable for a quantum state random optical signal according to the present invention.
Fig. 4 is a schematic block diagram of another embodiment of the modulator driving system suitable for quantum state random optical signals according to the present invention.
Fig. 5 is a flow chart illustrating a driving method of a modulator suitable for a quantum state random optical signal according to the present invention.
Description of the element reference numerals
100 modulator driving system suitable for quantum state random optical signal
110 input terminal group
1101 input terminal
1102 input terminal
1103 input terminal
110N input terminal
120 adjustable gain amplifier group
1201 variable gain amplifier
1202 adjustable gain amplifier
1203 adjustable gain amplifier
120N adjustable gain amplifier
130 broadband resistance network terminal
140 wide band amplifier
150 modulator
S110 to S150 steps
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
Please refer to fig. 2 to 5. It should be understood that the structures, ratios, sizes, and the like shown in the drawings are only used for matching the disclosure of the present disclosure, and are not used for limiting the conditions of the present disclosure, so that the present disclosure is not limited to the technical essence, and any modifications of the structures, changes of the ratios, or adjustments of the sizes, can still fall within the scope of the present disclosure without affecting the function and the achievable purpose of the present disclosure. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
The present embodiment aims to provide a method and a system for driving a modulator suitable for a quantum state random optical signal, which are used to solve the problems of substrate jitter and poor signal quality caused by insufficient low broadband frequency in the existing modulator driving system suitable for a quantum state random optical signal. The principle and implementation of the method and system for driving a modulator suitable for a quantum state random optical signal according to the present invention will be described in detail below, so that those skilled in the art can understand the method and system for driving a modulator suitable for a quantum state random optical signal without creative labor.
Example 1
As shown in fig. 2, the present embodiment provides a system 100 for driving a modulator 150 suitable for a quantum-state random optical signal, comprising: an input terminal set 110, an adjustable gain amplifier set 120, a broadband resistor network terminal 130, a broadband amplifier 140 and a modulator 150; wherein the input terminal set 110 includes at least two input terminals: input group 1101 to input group 110N; the set of adjustable gain amplifiers 120 comprises at least two adjustable gain amplifiers: tunable gain amplifiers 1201 through 120N, where N is a positive integer greater than or equal to 2.
The modulator driving system 100 applied to the quantum-state random optical signal of the present embodiment will be described in detail below.
The set of inputs 110 includes at least two inputs; each input terminal is used for inputting an aligned random input signal. In this embodiment, N is 2, and as shown in fig. 3, the input terminal set 110 includes an input terminal 1101 and an input terminal 1102; two aligned random input signals are input at input 1101 and input 1102. The two random input signals input at the input terminals 1101 and 1102 require signal alignment to align and superimpose in the resistor network of the subsequent stage, and the alignment method may be, but is not limited to, adding an optional adjustable delay circuit or other method to each of the two input signals.
The adjustable gain amplifier 120 is correspondingly connected to the input terminal group 110, the adjustable gain amplifier 120 includes at least two adjustable gain amplifiers, each of which is connected to the input terminal in a one-to-one correspondence manner, and is configured to amplify and adjust a gain of a corresponding random input signal and output an adjusted voltage signal, that is, the adjustable gain amplifier 120 is configured to amplify a received signal, and the gain is adjustable, so as to adjust a voltage value finally output to the modulator 150.
In this embodiment, N is 2, and the adjustable gain amplifier 120 includes an adjustable gain amplifier 1201 and an adjustable gain amplifier 1202 respectively; wherein, the output signal amplitude of one adjustable gain amplifier is half of that of the other adjustable gain amplifier. For example, the output signal amplitude of adjustable gain amplifier 1202 is half that of adjustable gain amplifier 1201.
In this embodiment, the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202 need to support low-frequency input as low as 0Hz (i.e. direct current), and the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202 are preferably adjustable gain amplifiers capable of adapting to direct current input and output signals, or the input end and the output end of the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202 may also be connected with ac coupling capacitors, respectively.
In this embodiment, the broadband resistive network terminal 130 is respectively connected to the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202, and is configured to combine the voltage signals output by the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202 and output a combined signal. The broadband resistor network of the broadband resistor network terminal 130 functions to combine and output multiple signals, and the resistor network is characterized by a wide bandwidth and a low frequency as low as 0Hz (i.e., direct current).
In this embodiment, the wideband amplifier 140 is connected to the wideband resistor network terminal 130, and is configured to amplify the combined signal to an amplitude required for modulation to form a driving signal.
In the present embodiment, the function of the wideband amplifier 140 is to amplify the input signal to a desired amplitude, the wideband amplifier 140 also needs to support a low-frequency input as low as 0Hz (i.e. direct current), the wideband amplifier 140 is preferably a wideband amplifier 140 that can adapt to a direct current input/output signal, or an input end and an output end of the wideband amplifier 140 may be connected with an ac coupling capacitor, respectively.
In this embodiment, a signal ground port of the modulator 150 is connected to a power supply, a power supply signal is processed by the modulator 150 (for example, through a matching resistor) and then loaded to the broadband amplifier 140 through a radio frequency port, and the modulator 150 receives the driving signal output by the broadband amplifier 140 from the radio frequency port and modulates the quantum state random optical signal input to the modulator 150 according to the driving signal.
It can be seen that, in the present embodiment, the power supply of the wideband amplifier is applied to the wideband amplifier from the signal ground port of the power supply entering the modulator 150 through the matching resistor (typically 50 ohms) of the modulator 150, and then the output of the RF port is loaded on the wideband amplifier, and the wideband amplifier does not use inductor or Bais _ T, etc. to ensure its working capability with low frequency as low as 0Hz (i.e. direct current).
Since the spectral components of the quantum state random optical signal are very wide, the low end is close to 0Hz (i.e. direct current), and the high end is several times of the system frequency, if the signal is amplified without distortion, the driving scheme covers the requirements of the low end and the high end. In practical application, a high end is easy to realize, a low end is difficult to realize, a low-end signal can be inhibited due to the existence of an alternating-current coupling capacitor and an inductor or a Bais _ T, and the low frequency of a drive circuit broadband is not low enough, so that the signal distortion after the random optical signal amplification can be caused, and the signal quality is poor. In the present embodiment, in the modulator driving system 100 suitable for the quantum-state random optical signal, the ac coupling capacitor and the inductor or Bais _ T are not used, and the dc matching is realized in the full channel design, so that the wideband driving circuit of 0Hz (i.e., dc) to 10GHz or more can be theoretically realized.
Therefore, the modulator driving system 100 suitable for the quantum state random optical signal in this embodiment can satisfy the broadband driving (the upper frequency limit of the scheme is theoretically unlimited) in the order of 0Hz (i.e., direct current) to 10GHz, perfectly solve the problem of substrate jitter of the existing driving circuit, greatly optimize the signal quality of the driving signal, enable the driving signal to be used in a system with higher signal quality requirement, and improve the performance of the system.
In this embodiment, the modulator 150 functions to receive a driving signal (RF signal) of the broadband amplifier from the RF port and then to control the modulation of the passing optical signal, and the modulator 150 may be a phase modulator or an intensity modulator, or other devices that can be driven by this type of driving signal.
The modulation amount of the modulator 150 for the quantum state random optical signal is a modulation amount corresponding to a difference between the voltage of the radio frequency port and the voltage of the signal ground port.
Specifically, in the present embodiment, since the signal ground of the modulator 150 is terminated by the power supply, the coding requirement for controlling the modulator 150 is as follows:
when the modulator 150 is in the unmodulated operating state, the random encoded signal of the modulator 150 outputs a high level signal, and a difference between the voltage of the radio frequency port and the voltage of the signal ground port is 0, that is, when modulation is not required, the random encoded signal should be output high, so that the RF end of the modulator 150 is also a power supply voltage, that is, a difference between the voltage of the RF port of the modulator 150 and the voltage of the signal ground port is 0. Because the modulator 150 is not modulating for most of the time, the voltage difference applied to the internal resistance of the modulator 150 is 0 for most of the time, which can reduce the heat generation of the modulator 150 and increase the lifetime.
When the modulator 150 is in the modulation operating state, the random encoding signal of the modulator 150 outputs a low level signal, and there is a difference between the voltage of the radio frequency port and the voltage of the signal ground port. That is, when modulation is required, the random code should be output low, so that a voltage difference is generated between the RF terminal and the signal ground terminal of the modulator 150, and the modulator 150 modulates the passing optical signal.
The specific implementation process of the modulator driving system 100 suitable for the quantum-state random optical signal in this embodiment is as follows:
in the field of quantum communication, four levels of random pulse signals 0, 1/2, 1, 3/2 are commonly used to modulate the modulator 150, in this embodiment, two paths of random input signals with aligned signals are given (alignment can be added at the back end), then the output signal amplitude of one adjustable gain amplifier can be configured to be half of that of another adjustable gain amplifier, and then the output signal amplitude is added in a back end broadband resistor network, so that after the random input signals are loaded at the input end 1101 and the input end 1102 respectively, four levels of driving signals 0, 1/2, 1, 3/2 can be added to drive the modulator 150, where 0, 1/2, 1, 3/2 only represents the number relationship rather than the actual amplitude.
Specifically, the signal amplitude of adjustable gain amplifier 1202 is 1/2, and the signal amplitude of adjustable gain amplifier 1201 is 1. When the adjustable gain amplifier 1201 and the adjustable gain amplifier 1202 do not output, the driving signal is a driving signal of 0 level; when the adjustable gain amplifier 1202 with the signal amplitude of 1/2 outputs and the adjustable gain amplifier 1201 does not output, the driving signal is a driving signal with the level of 1/2; when the adjustable gain amplifier 1201 with the signal amplitude of 1 outputs and the other adjustable gain amplifier 1202 does not output, the driving signal is a driving signal with the level of 1; when both of adjustable gain amplifiers 1201 and 1202 output, the driving signal is a 3/2 level driving signal formed by adding 1 level and 1/2 level.
The modulator driving system 100 suitable for the quantum-state random optical signal of the embodiment solves the substrate jitter problem of the existing driving circuit, greatly optimizes the signal quality of the driving signal, enables the driving signal to be used in a system with higher signal quality requirement, and improves the performance of the system.
Example 2
As shown in fig. 2, the present embodiment provides a modulator driving system 100 suitable for a quantum state random optical signal, comprising: an input terminal set 110, an adjustable gain amplifier set 120, a broadband resistor network terminal 130, a broadband amplifier 140 and a modulator 150; wherein the input terminal set 110 includes at least two input terminals: input group 1101 to input group 110N; the set of adjustable gain amplifiers 120 comprises at least two adjustable gain amplifiers: tunable gain amplifiers 1201 through 120N, where N is a positive integer greater than or equal to 2.
The modulator driving system 100 applied to the quantum-state random optical signal of the present embodiment will be described in detail below.
In this embodiment, the input terminal set 110 includes at least two input terminals; each input terminal is used for inputting an aligned random input signal, in this embodiment, N is 3, as shown in fig. 4, the input terminal set 110 includes an input terminal 1101, an input terminal 1102, and an input terminal 1103; the three random input signals input by the input terminal 1101, the input terminal 1102 and the input terminal 1103 require signal alignment so as to align and overlap in the post-stage resistor network, and the alignment method may be, but is not limited to, adding one optional adjustable delay circuit or other method to each of the three input signals.
The adjustable gain amplifier 120 is correspondingly connected with the input end group 110 and comprises at least two adjustable gain amplifiers; the adjustable gain amplifiers are connected with the input ends in a one-to-one correspondence mode and used for amplifying corresponding random input signals, adjusting gains and outputting adjusted voltage signals. That is, the adjustable gain amplifier 120 functions to amplify the received signal and has an adjustable gain for adjusting the voltage value finally output to the modulator 150.
In this embodiment, N is 3, and the adjustable gain amplifier 120 includes an adjustable gain amplifier 1201, an adjustable gain amplifier 1202, and an adjustable gain amplifier 1203; the output signal amplitudes of adjustable gain amplifier 1201, adjustable gain amplifier 1202 and adjustable gain amplifier 1203 are 1/2, 1 and 3/2, respectively, where 1/2, 1 and 3/2 only represent the magnitude relation and not the actual amplitude.
In this embodiment, the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203 need to support low-frequency input as low as 0Hz (i.e. direct current), and the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203 are preferably adjustable gain amplifiers capable of adapting to direct current input and output signals, or the input end and the output end of the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203 may also be connected with ac coupling capacitors, respectively.
In this embodiment, the broadband resistive network terminal 130 is respectively connected to the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203, and is configured to combine the voltage signals output by the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203 and output a combined signal. The broadband resistor network of the broadband resistor network terminal 130 functions to combine and output multiple signals, and the resistor network is characterized by a wide bandwidth and a low frequency as low as 0Hz (i.e., direct current).
In this embodiment, the wideband amplifier 140 is connected to the wideband resistor network terminal 130, and is configured to amplify the combined signal to an amplitude required for modulation to form a driving signal.
In the present embodiment, the function of the wideband amplifier is to amplify the input signal to a desired amplitude, the amplifier also needs to support a low-frequency input as low as 0Hz (i.e. direct current), the wideband amplifier 140 is preferably a wideband amplifier 140 that can adapt to the direct current input and output signals, or the input end and the output end of the wideband amplifier 140 may be connected with ac coupling capacitors, respectively.
In this embodiment, a signal ground port of the modulator 150 is connected to a power supply, a power supply signal is processed by the modulator 150 (for example, through a matching resistor) and then loaded to the broadband amplifier 140 through a radio frequency port, and the modulator 150 receives the driving signal output by the broadband amplifier 140 from the radio frequency port and modulates the quantum state random optical signal input to the modulator 150 according to the driving signal.
It can be seen that, in the present embodiment, the power supply of the wideband amplifier is applied to the wideband amplifier from the signal ground port of the power supply entering the modulator 150 through the matching resistor (typically 50 ohms) of the modulator 150, and then the output of the RF port is loaded on the wideband amplifier, and the wideband amplifier does not use inductor or Bais _ T, etc. to ensure its working capability with low frequency as low as 0Hz (i.e. direct current).
Since the spectral components of the quantum state random optical signal are very wide, the low end is close to 0Hz (i.e. direct current), and the high end is several times of the system frequency, if the signal is amplified without distortion, the driving scheme covers the requirements of the low end and the high end. In practical applications, the high side is easier to implement and the low side is more difficult to implement, and the low side signal is suppressed due to the presence of the ac coupling capacitor and inductor or Bais _ T. And the low frequency of the drive circuit broadband is not low enough, which can cause signal distortion after random optical signal amplification and signal quality deterioration. In the modulator driving system 100 suitable for the quantum-state random optical signal of the embodiment, ac coupling capacitors and inductors or Bais _ T are not used, and dc matching is realized in the full channel design, so that a wideband driving circuit of 0Hz (i.e., dc) to 10GHz or more can be theoretically realized.
Therefore, the modulator driving system 100 suitable for the quantum state random optical signal in this embodiment can satisfy the broadband driving (the upper frequency limit of the scheme is theoretically unlimited) in the order of 0Hz (i.e., direct current) to 10GHz, perfectly solve the problem of substrate jitter of the existing driving circuit, greatly optimize the signal quality of the driving signal, enable the driving signal to be used in a system with higher signal quality requirement, and improve the performance of the system.
In this embodiment, the modulator 150 functions to receive a driving signal (RF signal) of the broadband amplifier from the RF port and then to control the modulation of the passing optical signal, and the modulator 150 may be a phase modulator or an intensity modulator, or other devices that can be driven by this type of driving signal.
The modulation amount of the modulator 150 for the quantum state random optical signal is a modulation amount corresponding to a difference between the voltage of the radio frequency port and the voltage of the signal ground port.
Specifically, in the present embodiment, since the signal ground of the modulator 150 is terminated by the power supply, the coding requirement for controlling the modulator 150 is as follows:
when the modulator 150 is in the unmodulated operating state, the random encoded signal of the modulator 150 outputs a high level signal, and a difference between the voltage of the radio frequency port and the voltage of the signal ground port is 0, that is, when modulation is not required, the random encoded signal should be output high, so that the RF end of the modulator 150 is also a power supply voltage, that is, a difference between the voltage of the RF port of the modulator 150 and the voltage of the signal ground port is 0. Because the modulator 150 is not modulating for most of the time, the voltage difference applied to the internal resistance of the modulator 150 is 0 for most of the time, which can reduce the heat generation of the modulator 150 and increase the lifetime.
When the modulator 150 is in the modulation operating state, the random encoding signal of the modulator 150 outputs a low level signal, and there is a difference between the voltage of the radio frequency port and the voltage of the signal ground port. That is, when modulation is required, the random code should be output low, so that there is a voltage difference between the RF terminal and the signal ground terminal of the modulator 150, and the modulator 150 modulates the passing optical signal.
In a quantum communication system, the amplitude jitter value of the driving signal of the modulator 150 is a key index of the system, which directly affects the error rate of the system, and the system performance can be obviously improved by reducing the amplitude jitter value of the driving signal of the modulator 150. Theoretical analysis and experimental tests show that when the voltage 3/2 is generated by superimposing the voltage 1/2 and the voltage 1 in example 1, the amplitude jitter of the 3/2 voltage is further deteriorated on the basis of the jitter of the voltage 1/2 and the voltage 1, that is, the amplitude jitter of the voltage 1/2 and the voltage 1 is superimposed while signals are superimposed, so that the amplitude jitter of the voltage 3/2 is larger, and the overall performance of the system is reduced.
The specific implementation process of the modulator driving system 100 suitable for the quantum-state random optical signal in this embodiment is as follows:
in this embodiment, the input 1101, the input 1102, and the input 1103 provide random input signals with aligned three-way signals, and the adjustable gain amplifier 1201, the adjustable gain amplifier 1202, and the adjustable gain amplifier 1203 are adjusted to make the three-way signals generate 1/2, 1, and 3/2 voltages, respectively. When none of the variable gain amplifier 1201, the variable gain amplifier 1202, and the variable gain amplifier 1203 is powered by 0, voltage 1/2, 1, 3/2 may be generated in one of the three paths of the variable gain amplifier 1201, the variable gain amplifier 1202, and the variable gain amplifier 1203, so that driving signals of four levels, i.e., 0, 1/2, 1, 3/2, may be generated to drive the modulator 150. Therefore, the embodiment avoids the problem of 3/2 voltage amplitude jitter deterioration caused when 1/2 voltage and 1 voltage are superposed to generate 3/2 voltage, generates 3/2 voltage with better signal quality, greatly optimizes the signal quality of the driving signal and improves the system performance.
Example 3
The present embodiment provides a method for driving a modulator suitable for a quantum state random optical signal, as shown in fig. 5, the method for driving a modulator suitable for a quantum state random optical signal includes:
step S110, inputting at least two paths of aligned random input signals;
step S120, amplifying the input signal through at least two adjustable gain amplifiers 120, adjusting the gain, and outputting an adjusted voltage signal;
step S130, combining the output voltage signals through the broadband resistance network terminal 130 and outputting combined signals;
step S140, amplifying the combined signal to an amplitude required by modulation through a broadband amplifier 140 to form a driving signal;
step S150, connecting a signal ground port of the modulator 150 to a power supply, processing a power signal by the modulator 150, and then loading the power signal to the broadband amplifier 140 through a radio frequency port, where the modulator 150 receives the driving signal output by the broadband amplifier 140 from the radio frequency port and modulates the quantum state random optical signal input to the modulator 150 according to the driving signal.
In this embodiment, when the modulator 150 is in the unmodulated operating state, the random encoding signal of the modulator 150 outputs a high level signal, and a difference between the voltage of the rf port and the voltage of the signal ground port is 0; when the modulator 150 is in a modulation operating state, the random encoding signal of the modulator 150 outputs a low-level signal, a difference exists between the voltage of the radio frequency port and the voltage of the signal ground port, and the modulation amount of the modulator 150 on the quantum-state random optical signal is a modulation amount corresponding to the difference between the voltage of the radio frequency port and the voltage of the signal ground port.
The method in this embodiment may be implemented by the system of embodiment 1: through two inputs: the input end 1101 and the input end 1102 input two paths of aligned random input signals, and the adjustable gain amplifier group 120 correspondingly includes two adjustable gain amplifiers: tunable gain amplifier 1201 and tunable gain amplifier 1202; wherein, the output signal amplitude of one adjustable gain amplifier is half of that of the other adjustable gain amplifier. The implementation principle is the same as that of embodiment 1, and is not described herein again.
The method in this embodiment can also be implemented by the system of embodiment 2: through three inputs: the input 1101, the input 1102 and the input 1103 input three-way aligned random input signals, and the adjustable gain amplifier set 120 correspondingly includes three adjustable gain amplifiers: adjustable gain amplifier 1201, adjustable gain amplifier 1202, adjustable gain amplifier 1203; the output signal amplitudes of adjustable gain amplifier 1201, adjustable gain amplifier 1202 and adjustable gain amplifier 1203 are 1/2, 1 and 3/2, respectively. The implementation principle is the same as that of embodiment 2, and is not described again here.
In summary, the technical scheme of the present invention does not use ac coupling capacitors and inductors or Bais _ T, and dc matching is achieved in all channel designs, so that wideband driving from 0Hz (i.e. dc) to 10GHz or more can be achieved theoretically, wideband driving in the order of 0Hz (i.e. dc) to 10GHz (the upper frequency limit of the present solution is not limited theoretically) can be satisfied, the problem of substrate jitter of the existing driving circuit is effectively solved, the signal quality of the driving signal is greatly optimized, and the driving signal can be used in a system with higher signal quality requirement, and the performance of the system is improved. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention shall be covered by the claims of the present invention.
Claims (14)
1. A modulator driver system adapted for use with a quantum state random optical signal, comprising:
an input terminal group comprising at least two input terminals; each input end is used for inputting an aligned random input signal;
the adjustable gain amplifier group comprises at least two adjustable gain amplifiers; each adjustable gain amplifier is correspondingly connected with the input end one by one and used for amplifying the corresponding random input signal, adjusting the gain and outputting the adjusted voltage signal;
the broadband resistance network terminal is in communication connection with the adjustable gain amplifier group and is used for combining the voltage signals output by the adjustable gain amplifiers and outputting combined signals;
the broadband amplifier is in communication connection with the broadband resistance network terminal and is used for amplifying the combined signal to an amplitude required by modulation to form a driving signal;
a modulator; a signal ground port of the modulator is connected with a power supply, and a power supply signal is processed by the modulator and then loaded onto the broadband amplifier through a radio frequency port; the modulator receives the driving signal from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal.
2. The system of claim 1, wherein the modulator modulates the quantum state stochastic optical signal by a modulation amount corresponding to a difference between a voltage of the rf port and a voltage of the signal ground port.
3. The modulator driving system according to claim 2, wherein in the unmodulated operating state, the randomly encoded signal output by the modulator is a high-level signal, and the difference between the voltage at the rf port and the voltage at the signal ground port is 0; when the modulator is in a modulation working state, the random coding signal output by the modulator is a low-level signal, and the voltage of the radio frequency port and the voltage of the signal ground port have a difference value.
4. The modulator driving system according to claim 1, wherein the adjustable gain amplifier is an adjustable gain amplifier adapted to a dc input/output signal; the broadband amplifier is a broadband amplifier which can be adapted to direct current input and output signals.
5. The system of claim 1, wherein an ac coupling capacitor is connected to each of the input and output of the adjustable gain amplifier, and/or an ac coupling capacitor is connected to each of the input and output of the broadband amplifier.
6. The modulator driving system according to claim 1, wherein the input terminal set comprises two input terminals for inputting two aligned random input signals; the adjustable gain amplifier group comprises two adjustable gain amplifiers; and the amplitude of the output signal of one adjustable gain amplifier is half of that of the output signal of the other adjustable gain amplifier.
7. The modulator driving system according to claim 1, wherein said set of inputs comprises three inputs for inputting three-way aligned random input signals; the adjustable gain amplifier group comprises three adjustable gain amplifiers; the output signal amplitudes of the three adjustable gain amplifiers are 1/2, 1 and 3/2 respectively.
8. A method for driving a modulator suitable for a quantum state random optical signal, the method comprising:
inputting at least two paths of aligned random input signals;
amplifying the input signal through at least two adjustable gain amplifiers, adjusting the gain and outputting an adjusted voltage signal;
combining the output voltage signals through a broadband resistance network terminal and outputting combined signals;
amplifying the combined signal to an amplitude required by modulation through a broadband amplifier to form a driving signal;
and connecting a signal ground port of a modulator with a power supply, processing a power supply signal by the modulator, and then loading the power supply signal to the broadband amplifier through a radio frequency port, wherein the modulator receives the driving signal output by the broadband amplifier from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal.
9. The method as claimed in claim 8, wherein the modulation amount of the quantum state random optical signal by the modulator is a modulation amount corresponding to a difference between the voltage of the rf port and the voltage of the signal ground port.
10. The method as claimed in claim 9, wherein in the unmodulated operating state, the randomly encoded signal of the modulator outputs a high level signal, and the difference between the voltage of the rf port and the voltage of the signal ground port is 0; when the modulator is in a modulation working state, the random coding signal output by the modulator is a low-level signal, and the voltage of the radio frequency port and the voltage of the signal ground port have a difference value.
11. The method according to claim 8, wherein the adjustable gain amplifier is an adjustable gain amplifier adapted to a dc input/output signal; the broadband amplifier is a broadband amplifier which can be adapted to direct current input and output signals.
12. The method as claimed in claim 8, wherein an ac coupling capacitor is connected to each of the input and output terminals of the adjustable gain amplifier, and/or an ac coupling capacitor is connected to each of the input and output terminals of the broadband amplifier.
13. The method according to claim 8, wherein two paths of aligned random input signals are input, and the number of the adjustable gain amplifiers is two; and the amplitude of the output signal of one adjustable gain amplifier is half of that of the output signal of the other adjustable gain amplifier.
14. The method of claim 8, wherein three aligned random input signals are input, and the number of said tunable gain amplifiers is three; the output signal amplitudes of the three adjustable gain amplifiers are 1/2, 1 and 3/2 respectively.
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