CN111953426A - Photon-assisted ultra-wideband millimeter wave receiver based on Sagnac ring - Google Patents

Photon-assisted ultra-wideband millimeter wave receiver based on Sagnac ring Download PDF

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CN111953426A
CN111953426A CN202010772033.3A CN202010772033A CN111953426A CN 111953426 A CN111953426 A CN 111953426A CN 202010772033 A CN202010772033 A CN 202010772033A CN 111953426 A CN111953426 A CN 111953426A
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polarization
optical coupler
maintaining optical
phase modulator
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CN111953426B (en
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陶理
奚秀娟
李仁杰
陈亮
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China Ship Development and Design Centre
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/616—Details of the electronic signal processing in coherent optical receivers
    • H04B10/6165—Estimation of the phase of the received optical signal, phase error estimation or phase error correction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/616—Details of the electronic signal processing in coherent optical receivers
    • H04B10/6164—Estimation or correction of the frequency offset between the received optical signal and the optical local oscillator
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H04B10/69—Electrical arrangements in the receiver
    • H04B10/691—Arrangements for optimizing the photodetector in the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication

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Abstract

The invention discloses a photon-assisted ultra-wideband millimeter wave receiver based on a Sagnac ring, which belongs to the field of microwave photonics and comprises a phase modulator-based non-local oscillator microwave photon down-conversion device, wherein the phase modulator-based non-local oscillator microwave photon down-conversion device comprises the following components in percentage by weight: the millimeter wave radio frequency carrier signal directly drives the phase modulator, and the ultra wide band signal is modulated to a 1-order sideband output by the phase modulator; carrier suppression based on Sagnac loop: a Sagnac ring is introduced into a local oscillator-free microwave photon down-conversion structure based on a phase modulator, so that the central carrier suppression of the phase modulator output is realized, and 1-order sidebands are reserved. When the millimeter wave carrier frequency for driving the phase modulator changes, the central carrier can be inhibited, and the 1-order sideband can be reserved; photoelectric detection: and directly detecting a 1-order or-1-order sideband output by the Sagnac ring-based non-local-oscillator microwave photon down-conversion frequency conversion, or performing coherent detection, so as to realize photoelectric conversion, and finally completing the demodulation from the millimeter wave radio frequency signal to a baseband signal.

Description

Photon-assisted ultra-wideband millimeter wave receiver based on Sagnac ring
Technical Field
The invention belongs to the field of microwave photonics, and particularly relates to a photon-assisted ultra-wideband millimeter wave receiver based on a Sagnac ring.
Background
The shortage of spectrum resources promotes the evolution of communication frequency to higher frequency band, and millimeter wave band has several GHz available spectrum resources, which is the development direction of future wireless communication. The method is restricted by the processing rate of baseband signals and the bottleneck of an analog-digital/digital-analog conversion device, directly detects millimeter wave radio frequency signals with a plurality of GHz bandwidths, relates to electric domain frequency mixing and filtering, and has high device cost and great difficulty. The millimeter wave radio frequency signal can be directly converted to a baseband based on the microwave photon down-conversion technology, the characteristics of wide bandwidth, low loss and the like of an optical device are fully utilized, and the frequency mixing and filtering cost of the high-frequency radio frequency signal can be reduced. The typical microwave photon down-conversion method firstly performs electro-optical modulation on a received radio frequency signal, then selects a radio frequency local oscillator with a proper frequency to drive a cascaded electro-optical modulator, and then selects an optical wavelength modulated by the radio frequency signal and an optical wavelength modulated by the radio frequency local oscillator to perform optical heterodyne by using a tunable optical filter, so as to realize down-conversion of the radio frequency signal. For millimeter wave signal down conversion, the high frequency radio frequency local oscillator has high cost, and the use of two or more broadband modulators or specially customized modulators will further increase the system cost. In addition, signals output by a microwave photon down-conversion method usually with a radio frequency local oscillator drive are usually intermediate frequency signals, cannot be combined with a coherent detection technology, and cannot exert the performance advantage of coherent detection on weak light signal detection.
The traditional non-local-oscillator microwave photon down-conversion method extracts 1-order sideband wavelength of a carrier signal by using an optical filter, and then realizes photoelectric conversion by using a direct detection or coherent detection method, wherein the central wavelength of the optical filter needs to be adjusted according to the 1-order sideband optical wavelength, and if the variation range of the millimeter wave radio frequency carrier frequency is too large, the 1-order sideband optical wavelength exceeds the passband range of the optical filter, the signal power loss is increased until the correct demodulation cannot be realized, namely the bandwidth of a receiver is limited. In addition, the passband of a common optical filter is not flat, so that the loss of different optical wavelengths after passing is different, the demodulation performance of the receiver on millimeter wave signals with different carrier frequencies is different, and the realization of ultra-wideband frequency hopping transmission by millimeter waves is not facilitated.
Disclosure of Invention
Aiming at the defects or improvement requirements in the prior art, the invention provides a Sagnac ring-based photon-assisted ultra-wideband millimeter wave receiver, which adopts the Sagnac ring to suppress the carrier of the local oscillator-free microwave photon down-conversion output signal, combines with the photoelectric detection technology, realizes the reception and demodulation of ultra-wideband millimeter wave radio-frequency signals, and supports the large-capacity and long-distance transmission of millimeter wave wireless communication.
In order to achieve the above object, the present invention provides a photon-assisted ultra-wideband millimeter wave receiver based on a Sagnac loop, comprising: the device comprises a local oscillator-free microwave photon down-conversion structure, a Sagnac ring and a detection unit;
the Sagnac ring is used for inhibiting the central carrier wave obtained through the local oscillator-free microwave photon down-conversion structure and reserving a 1-order sideband;
the detection unit is used for detecting 1-order or-1-order sidebands.
Preferably, the local oscillator-free microwave photon down-conversion structure comprises an external cavity laser, an optical isolator and a phase modulator which are connected in sequence.
Preferably, the millimeter wave receiver further includes: a polarization maintaining optical coupler; the first end of polarization-maintaining optical coupler is connected with the output end of the optical isolator, the second end of the polarization-maintaining optical coupler is connected with one end of the phase modulator, the other end of the phase modulator is connected with the fourth end of the polarization-maintaining optical coupler, and the third end of the polarization-maintaining optical coupler is connected with the detection unit.
Preferably, the Sagnac loop is formed by the second end of the polarization maintaining optical coupler, the fourth end of the polarization maintaining optical coupler, and the phase modulator.
Preferably, the continuous wave generated by the external cavity laser is injected into the first port of the polarization-maintaining optical coupler after passing through the optical isolator, and after being coupled to the phase modulator via the second port of the polarization-maintaining optical coupler clockwise, the continuous wave enters the fourth port of the polarization-maintaining optical coupler, meanwhile, the output coupled to the fourth port by the first port of the polarization-maintaining optical coupler propagates counterclockwise in the Sagnac loop and is coupled to the fourth port through the second port of the polarization-maintaining optical coupler, and the output coupled to the fourth port counterclockwise through the second port of the polarization-maintaining optical coupler interferes with the output coupled to the fourth port clockwise through the second port of the polarization-maintaining optical coupler to obtain a final output signal of the fourth port.
Preferably, the detection unit is configured to detect a 1-order or-1-order sideband output from the fourth port of the polarization maintaining optical coupler to the third port, so as to implement photoelectric conversion and complete demodulation from a millimeter wave radio frequency signal to a baseband signal.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
the invention adopts a Sagnac ring-based non-local oscillator microwave photon down-conversion structure to realize the central carrier suppression of the phase modulator output, improves the conversion efficiency of the non-local oscillator microwave photon down-conversion, realizes down-conversion of any millimeter wave radio frequency carrier signal, and supports large-capacity and long-distance transmission of millimeter wave wireless communication. The invention solves the problem of ultra-wideband demodulation of any millimeter wave carrier frequency in millimeter wave wireless communication, and can be applied to an ultra-wideband millimeter wave wireless communication system. The method has the advantages of simple principle, simple and efficient scheme and high application value.
Drawings
Fig. 1 is a schematic diagram of a structure of a photon-assisted ultra-wideband millimeter wave receiver based on a Sagnac loop according to an embodiment of the present invention, where ECL denotes an external cavity laser, ISO denotes an optical isolator, PM-OC denotes a polarization-maintaining optical coupler, and PM denotes an optical phase modulator;
fig. 2 is a spectrum of a local oscillator-free microwave photon down-conversion output spectrum based on a Sagnac loop according to an embodiment of the present invention;
fig. 3 is a millimeter wave receiver based on a conventional local oscillator-free microwave photon down-conversion structure according to an embodiment of the present invention, where ECL denotes an external cavity laser, ISO denotes an optical isolator, PM denotes an optical phase modulator, and FBG denotes a fiber bragg grating;
fig. 4 shows error performance of an ultra-wideband photon-assisted millimeter wave receiver based on a Sagnac loop according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present examples, "first", "second", etc. are used for distinguishing different objects, and are not necessarily used for describing a particular order or sequence.
The invention provides a photon-assisted ultra-wideband millimeter wave receiver structure based on a Sagnac ring.
The ultra-wideband in the embodiment of the invention is as follows: the bandwidth of signals carried by millimeter wave radio frequency carriers is wide, and is generally in the range of GHz to tens of GHz.
As shown in fig. 1, first, a continuous Optical wave generated by an External Cavity Laser (ECL) passes through an Optical Isolator (ISO) and is injected into a PM-OC port 1 of a polarization maintaining Optical coupler (PM-OC), and the outputs of a PM-OC port 2 and a port 4 are expressed as follows:
Figure BDA0002617006280000041
Figure BDA0002617006280000042
wherein E isc＝Aexp(jwct), A is the output electric field intensity of the light source, wcIs the center carrier frequency.
After the signal of the PM-OC port 2 is coupled to the PM for modulation, the optical signal output by the PM driven by the millimeter wave radio frequency signal is as follows:
Figure BDA0002617006280000043
wherein, Vd＝RVπsin(wst)，ws＝2πfs，fsIs a millimeter wave radio frequency carrier frequency, VπFor the half-wave voltage of the phase modulator, R is the ratio of the amplitude of the rf signal to the amplitude of the half-wave voltage, so equation (3) can be expressed as follows:
Figure BDA0002617006280000051
the Bessel function expansion is performed on the above equation as:
Figure BDA0002617006280000052
wherein, Jn(π R) is an n-th order Bessel function of the first kind, and generally the millimeter wave wireless communication signal receiving end has low power, resulting in a small R, and therefore only 1-order sidebands are generally generated, so equation (5) can be expressed as follows:
Figure BDA0002617006280000053
the output coupled to port 3 via PM-OC port 4 is as follows:
Figure BDA0002617006280000054
the output of the optical signal output by the ECL coupled to port 4 through PM-OC port 1 propagates counter-clockwise within the Sagnac loop, and since the PM modulator counter-injection does not modulate, the optical signal propagating counter-clockwise coupled to port 3 through PM-OC port 2 is represented as follows:
Figure BDA0002617006280000055
the final PM-OC port 3 output signal is represented as follows:
Figure BDA0002617006280000056
considering that the output signal of the millimeter wave signal after long-distance transmission is weaker at the rear end of the receiving antenna, R is smaller, J0(π R) is close to 1 and the first term in equation (9) approaches 0, so that the center carrier is suppressed. The output of the PM-OC port 4 is the second term of equation (9), which represents the 1-order sideband output by the phase modulator, and the demodulation of the signal can be realized by directly detecting or coherently detecting the 1-order sideband.
Fig. 2 shows a typical case result of the implementation of the present invention, a millimeter wave wireless communication system is built, the millimeter wave radio frequency is 80GHz, the modulation format adopts 16-order Quadrature Amplitude Modulation (QAM), the system baud rate is 5Gbaud, and the receiver detection mode is coherent detection.
By adopting the structure of the Sagnac loop-based photon-assisted ultra-wideband millimeter wave receiver shown in fig. 1 and comparing the performance with the millimeter wave receiver of the conventional non-local oscillator microwave photon down-conversion structure shown in fig. 3, fig. 2 shows the output spectra of the phase modulators in the two microwave photon down-conversion structures based on the phase modulators, it can be seen that after the Sagnac loop structure is adopted, the central carrier of the output spectra is obviously suppressed, and fig. 4 shows the error code performance of the system.
The above embodiments are only typical applications of the present invention, and baseband signal modulation modes of different orders (such as QPSK, 8PSK modulation, etc.), direct detection instead of coherent detection, etc. are all specific implementations of the present invention.
The photon-assisted ultra-wideband millimeter wave receiver structure based on the Sagnac ring comprises main technologies of local oscillator-free microwave photon down-conversion based on a phase modulator, Sagnac ring carrier suppression, photoelectric detection and the like. Wherein, no local oscillator microwave photon down conversion based on phase modulator includes: the millimeter wave radio frequency carrier signal directly drives the phase modulator, and the ultra wide band signal is modulated to a 1-order sideband output by the phase modulator; the carrier suppression based on the Sagnac loop comprises the following steps: a Sagnac ring is introduced into a local oscillator-free microwave photon down-conversion structure based on a phase modulator, so that the central carrier suppression of the phase modulator output is realized, and 1-order sidebands are reserved. When the millimeter wave carrier frequency for driving the phase modulator changes, the central carrier can be inhibited, and the 1-order sideband can be reserved; the photoelectric detection comprises the following steps: and directly detecting a 1-order or-1-order sideband output by the Sagnac ring-based non-local-oscillator microwave photon down-conversion frequency conversion, or performing coherent detection, so as to realize photoelectric conversion, and finally completing the demodulation from the millimeter wave radio frequency signal to a baseband signal.
It should be noted that, according to the implementation requirement, each step/component described in the present application can be divided into more steps/components, and two or more steps/components or partial operations of the steps/components can be combined into new steps/components to achieve the purpose of the present invention.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (6)

1. A photon-assisted ultra-wideband millimeter wave receiver based on a Sagnac ring is characterized by comprising: the device comprises a local oscillator-free microwave photon down-conversion structure, a Sagnac ring and a detection unit;
the Sagnac ring is used for inhibiting the central carrier wave obtained through the local oscillator-free microwave photon down-conversion structure and reserving a 1-order sideband;
the detection unit is used for detecting 1-order or-1-order sidebands.
2. The millimeter wave receiver of claim 1, wherein the non-local oscillator microwave photon down conversion structure comprises an external cavity laser, an optical isolator and a phase modulator connected in sequence.
3. The millimeter-wave receiver according to claim 2, characterized in that the millimeter-wave receiver further comprises: a polarization maintaining optical coupler; the first end of polarization-maintaining optical coupler is connected with the output end of the optical isolator, the second end of the polarization-maintaining optical coupler is connected with one end of the phase modulator, the other end of the phase modulator is connected with the fourth end of the polarization-maintaining optical coupler, and the third end of the polarization-maintaining optical coupler is connected with the detection unit.
4. The millimeter-wave receiver of claim 3, wherein the Sagnac loop is formed by the second end of the polarization-maintaining optical coupler, the fourth end of the polarization-maintaining optical coupler, and the phase modulator.
5. The millimeter wave receiver of claim 4, wherein the continuous wave generated by the external cavity laser is injected into the first port of the polarization maintaining optical coupler after passing through the optical isolator, and enters the fourth port of the polarization maintaining optical coupler after being coupled to the phase modulator via the second port of the polarization maintaining optical coupler clockwise, meanwhile, the output coupled to the fourth port by the first port of the polarization-maintaining optical coupler propagates anticlockwise in the Sagnac loop and is coupled to the fourth port through the second port of the polarization-maintaining optical coupler, and the output coupled to the fourth port anticlockwise through the second port of the polarization-maintaining optical coupler interferes with the output coupled to the fourth port clockwise through the second port of the polarization-maintaining optical coupler to obtain a final output signal of the fourth port.
6. The millimeter wave receiver according to claim 5, wherein the detection unit is configured to detect a 1 st order or a-1 st order sideband output from the fourth port of the polarization maintaining optical coupler to the third port, so as to perform photoelectric conversion and complete demodulation of the millimeter wave radio frequency signal to a baseband signal.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113162694A (en) * 2021-02-23 2021-07-23 复旦大学 Photon auxiliary vector millimeter wave signal generation system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105763260A (en) * 2016-01-16 2016-07-13 西安电子科技大学 Device and method of generating triangular waves by using phase modulator and Sagnac ring
CN106100748A (en) * 2016-05-27 2016-11-09 西安电子科技大学 Phase-modulator and adjustable chromatic dispersion device is utilized to generate the device and method of microwave waveform
US20190346739A1 (en) * 2018-05-10 2019-11-14 Ut-Battelle, Llc Gain balanced nonlinear optical interferometer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105763260A (en) * 2016-01-16 2016-07-13 西安电子科技大学 Device and method of generating triangular waves by using phase modulator and Sagnac ring
CN106100748A (en) * 2016-05-27 2016-11-09 西安电子科技大学 Phase-modulator and adjustable chromatic dispersion device is utilized to generate the device and method of microwave waveform
US20190346739A1 (en) * 2018-05-10 2019-11-14 Ut-Battelle, Llc Gain balanced nonlinear optical interferometer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113162694A (en) * 2021-02-23 2021-07-23 复旦大学 Photon auxiliary vector millimeter wave signal generation system
CN113162694B (en) * 2021-02-23 2022-12-20 复旦大学 Photon auxiliary vector millimeter wave signal generation system

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