Transceiving chip for microwave and infrared dual-band free space communication

Abstract

The invention discloses a transceiving chip for microwave and infrared dual-band free space communication. The transceiving chip is integrated with a grating coupler array, a microwave beam forming network, an optical coherent transceiver and an optical phased array. The invention provides the transceiver chip integrated with the microwave beam forming network, the optical coherent transceiver and the optical phased array, and the transceiver chip is low in cost and high in compactness, and can meet the requirements of low earth orbit satellites on rapid increase of high speed and broadband bandwidth for ground communication and inter-satellite communication.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communication and optoelectronic integration, and in particular, relates to a microwave and infrared dual-band free-space communication transceiver chip. Background Art

[0002] With the rapid development of low earth orbit (LEO) satellite communication networks, the demand for high-speed and stable data transmission in global communication systems continues to grow. Future communication systems not only need to cover a wide geographical area, but also need to be able to handle large amounts of data. To this end, multi-band communication technology becomes the key, which can optimize the bandwidth and connectivity of communication links by utilizing different frequency bands from microwaves to infrared and even visible light. Especially in the field of satellite communications, the use of multiple frequency bands to achieve high-speed and reliable communications helps to establish low-latency, high-bandwidth connections between fast-moving satellites and between satellites and ground stations.

[0003] Among these communication frequency bands, the microwave band is suitable for communication scenarios with longer distances and stronger penetration due to its long wavelength characteristics, and is used for communication between satellites and ground stations; while the infrared band can provide higher bandwidth and higher communication rate, and is used for communication between satellites. Therefore, combining the two frequency bands of microwave and infrared can greatly increase the data transmission speed while maintaining long-distance communication capabilities. Therefore, it is necessary to provide a transceiver chip for free-space communication with dual-band microwave and infrared. Summary of the invention

[0004] The present invention provides a compact, integrated solution that supports both microwave and infrared dual-band communications and optical coherent transceiver systems. In addition, the solution also combines optical phased array and microwave beamforming technology to optimize the performance of the communication link.

[0005] Therefore, according to one aspect of the present invention, a transceiver chip for microwave and infrared dual-band free-space communication is provided, which integrates a grating coupler array, a microwave beamforming network, an optical coherent transceiver and an optical phased array.

[0006] In an example of the transceiver chip provided in the above aspect, the microwave beamforming network includes: an on-chip modulator, N on-chip optical switch delay lines and N photodetectors; the on-chip modulator is used to receive microwave signals and receive laser signals through the grating coupler array, and modulate the microwave signals onto the laser signals, and output four modulated laser signals; the i-th on-chip optical switch delay line is used to adjust the delay of the i-th modulated laser signal; the i-th photodetector is used to convert the i-th delay-adjusted laser signal into a microwave signal; wherein, 1≤i≤N.

[0007] In an example of the transceiver chip provided in the above aspect, the on-chip modulator includes: a Mach-Zehnder modulator, a first 1×2 multimode interferometer, a 2×2 multimode interferometer, a second 1×2 multimode interferometer and a third 1×2 multimode interferometer; the grating coupler array includes a second grating coupler, a third grating coupler and a fourth grating coupler; the first input port of the Mach-Zehnder modulator is connected to the second grating coupler for receiving a laser signal, the second input port of the Mach-Zehnder modulator is used to receive a microwave signal, the Mach-Zehnder modulator is used to modulate the microwave signal onto the laser signal, and its output port is used to output the modulated laser signal; the input port of the first 1×2 multimode interferometer is connected to the output port of the Mach-Zehnder modulator outlet, and its first output port is connected to the third grating coupler, and its second output port is connected to the second input port of the 2×2 multimode interferometer; the first input port of the 2×2 multimode interferometer is connected to the fourth grating coupler, and its first output port is connected to the input port of the second 1×2 multimode interferometer, and its second output port is connected to the input port of the third 1×2 multimode interferometer; the first output port of the second 1×2 multimode interferometer is connected to the first on-chip optical switch delay line, the second output port of the second 1×2 multimode interferometer is connected to the second on-chip optical switch delay line, the first output port of the third 1×2 multimode interferometer is connected to the third on-chip optical switch delay line, and the second output port of the third 1×2 multimode interferometer is connected to the fourth on-chip optical switch delay line.

[0008] In an example of the transceiver chip provided in the above aspect, the i-th on-chip optical delay line includes: a first optical switch, a first long waveguide, a second optical switch, a second long waveguide, a third optical switch, a third long waveguide and a fourth optical switch; the grating coupler array also includes a 2i+3 grating coupler and a 2i+4 grating coupler; the first input port of the first optical switch is connected to the 2i+3 grating coupler, the second input port of the first optical switch is connected to the first output port of the second 1×2 multimode interferometer, the first output port of the first optical switch is connected to one end of the first long waveguide, and the second output port of the first optical switch is connected to the second input port of the second optical switch; the first The first input port of the optical switch is connected to the other end of the first long waveguide, the first output port of the second optical switch is connected to one end of the second long waveguide, and the second output port of the second optical switch is connected to the second input port of the third optical switch; the first input port of the third optical switch is connected to the other end of the second long waveguide, the first output port of the third optical switch is connected to one end of the third long waveguide, and the second output port of the third optical switch is connected to the second input port of the fourth optical switch; the first input port of the fourth optical switch is connected to the other end of the third long waveguide, the first output port of the fourth optical switch is connected to the 2i+4th grating coupler, and the second output port of the fourth optical switch is connected to the i-th photodetector.

[0009] In an example of the transceiver chip provided in the above aspect, the optical transceiver coherent device is used to receive a local oscillator laser signal and a laser signal to be demodulated, and demodulate a codirectional microwave signal and an orthogonal microwave signal according to the received local oscillator laser signal and the laser signal to be demodulated.

[0010] In an example of the transceiver chip provided in the above aspect, the optical transceiver coherent device includes: first and second 1×2 multimode interferometers, first and second thermal phase shifters, a crossover, first and second 2×2 multimode interferometers, and first and second balanced detectors; the first 1×2 multimode interferometer is used to receive a local oscillator laser signal, and divide the received local oscillator laser signal into a first local oscillator laser signal and a second local oscillator laser signal; the second 1×2 multimode interferometer is used to receive a laser signal to be demodulated, and divide the received laser signal to be demodulated into a first laser signal to be demodulated and a second laser signal to be demodulated; the first 2×2 multimode interferometer is used to receive the first local oscillator laser signal through the first thermal phase shifter, and is used to receive the second local oscillator laser signal through the crossover. The invention relates to a laser signal to be demodulated; the second 2×2 multimode interferometer is used to receive the first laser signal to be demodulated through the second thermal phase shifter, and is used to receive the second local oscillator laser signal through the crossover; the first balanced detector is used to receive the first local oscillator laser signal and the second laser signal to be demodulated after being processed by the first 2×2 multimode interferometer; the second balanced detector is used to receive the second local oscillator laser signal and the first laser signal to be demodulated after being processed by the second 2×2 multimode interferometer; wherein the phase difference between the local oscillator laser signal and the laser signal to be demodulated is adjusted by controlling the voltage of at least one of the first and second thermal phase shifters, so that the first and second balanced detectors respectively output the demodulated co-directional microwave signal and orthogonal microwave signal.

[0011] In an example of the transceiver chip provided in the above aspect, the input port of the first 1×2 multimode interferometer is connected to the 2N+5th grating coupler to receive the local oscillator laser signal, the first output port of the first 1×2 multimode interferometer is connected to one end of the first thermal phase shifter, and the second output port of the first 1×2 multimode interferometer is connected to the crossover; the input port of the second 1×2 multimode interferometer is connected to the 2N+6th grating coupler to receive the laser signal to be demodulated, the first output port of the second 1×2 multimode interferometer is connected to one end of the second thermal phase shifter, and the second output port of the second 1×2 multimode interferometer is connected to the crossover; A first input port of a 2×2 multimode interferometer is connected to the other end of a first thermal phase shifter, a second input port of the first 2×2 multimode interferometer is connected to a crossover, and a first output port and a second output port of the first 2×2 multimode interferometer are both connected to a first balanced detector; a first input port of a second 2×2 multimode interferometer is connected to the other end of a second thermal phase shifter, a second input port of the second 2×2 multimode interferometer is connected to a crossover, and a first output port and a second output port of the second 2×2 multimode interferometer are both connected to a second balanced detector; wherein N is the total number of on-chip optical switch delay lines of the microwave beamforming network.

[0012] In an example of the transceiver chip provided in the above aspect, the optical phased array includes: an on-chip dual parallel Mach-Zehnder modulator, a beam splitter, M thermal phase shifters and M waveguide gratings; the dual parallel Mach-Zehnder modulator is used to receive microwave signals and laser signals, and modulate the microwave signals onto the laser signals; the beam splitter is used to divide the modulated laser signal into M paths; the j-th thermal phase shifter and the j-th waveguide grating are used to sequentially allow the j-th modulated laser signal to pass through, 1≤j≤M; wherein the phase difference between the laser signals radiated from each waveguide grating is changed by controlling the voltage of each thermal phase shifter, thereby controlling the azimuth angle of the radiated laser signal.

[0013] In an example of the transceiver chip provided in the above aspect, the dual parallel Mach Zehnder modulator includes: a 1×2 multimode interferometer, a first and a second Mach Zehnder modulator, a thermal phase shifter, and a first and a second 2×2 multimode interferometer; the input port of the 1×2 multimode interferometer is connected to the 2N+9 grating coupler to receive a laser signal, the first output port of the 1×2 multimode interferometer is connected to the first input port of the first Mach Zehnder modulator, and the second output port of the 1×2 multimode interferometer is connected to the first input port of the second Mach Zehnder modulator; the second input port of the first Mach Zehnder modulator is used to receive a microwave signal, and the output port of the first Mach Zehnder modulator is connected to one end of the thermal phase shifter; the second Mach Zehnder The second input port of the Mach-Zehnder modulator is used to receive a microwave signal, and the output port of the second Mach-Zehnder modulator is connected to the second input port of the first 2×2 multimode interferometer; the first input port of the first 2×2 multimode interferometer is connected to the other end of the thermal phase shifter, the first output port of the first 2×2 multimode interferometer is connected to the first input port of the second 2×2 multimode interferometer, and the second output port of the first 2×2 multimode interferometer is connected to the 2N+8th grating coupler; the second input port of the second 2×2 multimode interferometer is connected to the 2N+7th grating coupler, and the first output port and the second output port of the second 2×2 multimode interferometer are both connected to the beam splitter; wherein N is the total number of on-chip optical switch delay lines of the microwave beamforming network.

[0014] In an example of the transceiver chip provided in the above aspect, the beam splitter includes: M / 8 first 1×2 multimode interferometers, M / 4 second 1×2 multimode interferometers and M / 2 second 1×2 multimode interferometers; the input ports of the M / 8 first 1×2 multimode interferometers are all connected to the output ports of the 2×2 multimode interferometers, the input ports of the M / 4 second 1×2 multimode interferometers are all connected to the output ports of the M / 8 first 1×2 multimode interferometers, the input ports of the M / 2 second 1×2 multimode interferometers are all connected to the output ports of the M / 4 second 1×2 multimode interferometers, and the M output ports of the M / 2 second 1×2 multimode interferometers are respectively connected to corresponding thermal phase shifters.

[0015] Beneficial effects: The present invention provides a transceiver chip integrating a microwave beamforming network, an optical coherent transceiver and an optical phased array. The transceiver chip is low-cost and highly compact, and can meet the rapidly growing demand for high-speed and broadband bandwidth for low-Earth orbit satellite-to-ground and inter-satellite communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features and advantages of the embodiments of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0017] Figure 1 is a schematic diagram of various sub-components used in a transceiver chip for microwave and infrared dual-band free-space communication according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of a microwave and infrared dual-band free-space communication transceiver chip according to an embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of a control voltage of a thermal phase shifter loaded into an optical switch and a transmittance of an optical switch port according to an embodiment of the present invention;

[0020] Figure 4 is a constellation diagram after a microwave signal transmitted by a microwave beamforming network according to an embodiment of the present invention is received and demodulated;

[0021] Figure 5 is a spot diagram of a near-infrared band radiated by an optical phased array according to an embodiment of the present invention;

[0022] Figure 6 1 is a constellation diagram after the laser signal radiated by the optical phased array according to the embodiment of the present invention is input into the optical coherent transceiver through the fourteenth grating coupler for demodulation. DETAILED DESCRIPTION

[0023] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention may be implemented in many different forms, and the present invention should not be construed as being limited to the specific embodiments set forth herein. On the contrary, these embodiments are provided to explain the principles of the present invention and their practical applications, so that other persons skilled in the art can understand the various embodiments of the present invention and various modifications suitable for specific intended applications.

[0024] As used herein, the term "including" and its variations represent open terms, meaning "including but not limited to". The terms "based on", "according to", etc. mean "based at least in part on", "based at least in part on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other definitions may be included below, whether explicit or implicit. Unless the context clearly indicates otherwise, the definition of a term is consistent throughout the specification.

[0025] Figure 1 It is a schematic diagram of various sub-components used in a transceiver chip for microwave and infrared dual-band free space communication according to an embodiment of the present invention.

[0026] exist Figure 1 In the example, "in1" indicates the first input port of a sub-device, and "in2" indicates the second input port of a sub-device; correspondingly, "out1" indicates the first output port of a sub-device, and "out2" indicates the second output port of a sub-device. Figure 1 The description also applies to “in1”, “in2”, “out1” and “out2” appearing in other drawings in this application document.

[0027] In addition, Figure 1 In Figure (g), Δτ represents a long waveguide with a delay of Δτ, 2Δτ represents a long waveguide with a delay of 2Δτ, and 4Δτ represents a long waveguide with a delay of 4Δτ.

[0028] Figure 2 Schematic diagram of a microwave and infrared dual-band free-space communication transceiver chip according to an embodiment of the present invention.

[0029] Reference Figure 2 According to the embodiment of the present invention, the microwave and infrared dual-band free space communication transceiver chip integrates a grating coupler array a, a microwave beamforming network b, an optical coherent transceiver c, and an optical phased array d. Of course, it should be understood that other suitable devices may also be specifically provided on the transceiver chip, such as a radio frequency connector ( Figure 1 The RF interface is connected as shown in Figure (J).

[0030] Therefore, according to an embodiment of the present invention, a compact, integrated transceiver chip is provided that can simultaneously support microwave and infrared dual-band communications and optical coherent transceiver systems. Further, the transceiver chip also combines optical phased array and microwave beamforming technology to optimize the performance of the communication link. Below, each subunit of the transceiver chip (i.e., subunits a, b, c, and d) will be described in detail.

[0031] Continue to refer to Figure 2 The grating coupler array a is used to introduce the optical signal into the chip, and includes a plurality of grating couplers. In this embodiment, the grating coupler array a includes 18 grating couplers, but the present invention is not limited thereto. The first grating coupler a1 is connected to the eighteenth grating coupler a18 using an optical waveguide.

[0032] The microwave beamforming network b includes: an on-chip modulator, N on-chip optical switch delay lines, and N photodetectors. The on-chip modulator is used to receive microwave signals and receive laser signals through the grating coupler array, modulate the microwave signals onto the laser signals, and output four modulated laser signals; the i-th on-chip optical switch delay line is used to adjust the delay of the i-th modulated laser signal; the i-th photodetector is used to convert the i-th delay-adjusted laser signal into a microwave signal; wherein, 1≤i≤N. In this embodiment, N is 4, but the present invention is not limited thereto, and the relevant number can be set according to the actual application scenario.

[0033] Specifically, the on-chip modulator includes: a Mach-Zehnder modulator b1, a first 1×2 multimode interferometer b21, a 2×2 multimode interferometer b3, a second 1×2 multimode interferometer b22 and a third 1×2 multimode interferometer b23.

[0034] The first input port of the Mach-Zehnder modulator b1 is connected to the second grating coupler a2 to receive a laser signal (e.g., a single-wavelength laser signal) generated by, for example, an off-chip light source. The second input port of the Mach-Zehnder modulator b1 is used to receive a microwave signal through a radio frequency interface. The Mach-Zehnder modulator b1 is used to modulate the microwave signal onto the laser signal, and its output port is used to output the modulated laser signal.

[0035] The input port of the first 1×2 multimode interferometer b21 is connected to the output port of the Mach-Zehnder modulator b1, and its first output port is connected to the third grating coupler a3 through an optical waveguide, and its second output port is connected to the second input port of the 2×2 multimode interferometer b3. The first 1×2 multimode interferometer b21 is used to split the energy of the modulated laser signal into two, wherein 50% of the energy is output from the first output port, and the other 50% of the energy is output from the second output port.

[0036] The first input port of the 2×2 multimode interferometer b3 is connected to the fourth grating coupler a4 to couple multiple single-wavelength lasers or wide-spectrum lights output by the off-chip light source to the chip. The first output port of the 2×2 multimode interferometer b3 is connected to the input port of the second 1×2 multimode interferometer b22, and its second output port is connected to the input port of the third 1×2 multimode interferometer b23. The first output port of the second 1×2 multimode interferometer b22 is connected to the first on-chip optical switch delay line, and the second output port of the second 1×2 multimode interferometer b22 is connected to the second on-chip optical switch delay line. The first output port of the third 1×2 multimode interferometer b23 is connected to the third on-chip optical switch delay line, and the second output port of the third 1×2 multimode interferometer b23 is connected to the fourth on-chip optical switch delay line. Thus, the energy of the light input to the first input port and the second input port of the 2×2 multimode interferometer b3 is divided into four by the second 1×2 multimode interferometer b22 and the third 1×2 multimode interferometer b23, and then respectively input into the four on-chip optical delay lines. Since the structures and functions of the on-chip optical delay lines of each path are the same, the fourth on-chip optical delay line is selected for detailed description in this embodiment.

[0037] The fourth on-chip optical delay line includes: a first optical switch b4, a first long waveguide b5, a second optical switch b6, a second long waveguide b7, a third optical switch b8, a third long waveguide b9 and a fourth optical switch b10.

[0038] The first input port of the first optical switch b4 is connected to the 11th grating coupler, the second input port of the first optical switch b4 is connected to the first output port of the second 1×2 multimode interferometer b22, the first output port of the first optical switch b4 is connected to one end of the first long waveguide b5, and the second output port of the first optical switch b4 is connected to the second input port of the second optical switch b6.

[0039] The first input port of the second optical switch b6 is connected to the other end of the first long waveguide b5, the first output port of the second optical switch b6 is connected to one end of the second long waveguide b7, and the second output port of the second optical switch b6 is connected to the second input port of the third optical switch b8.

[0040] The first input port of the third optical switch b8 is connected to the other end of the second long waveguide b7, the first output port of the third optical switch b8 is connected to one end of the third long waveguide b9, and the second output port of the third optical switch b8 is connected to the second input port of the fourth optical switch b10.

[0041] A first input port of the fourth optical switch b10 is connected to the other end of the third long waveguide b9, a first output port of the fourth optical switch b10 is connected to the 12th grating coupler, and a second output port of the fourth optical switch b10 is connected to the fourth photodetector.

[0042] The fourth photodetector is used to convert the laser signal into a microwave signal, which is output to the array microwave antenna outside the chip through the microstrip line and the radio frequency interface (and the radio frequency connector connected thereto), and finally emitted into the free space to realize microwave communication. In addition, by controlling the first optical switch b4, the second optical switch b6, the third optical switch b8 and the fourth optical switch b10, the delay of the microwave signal output by the four photodetectors can be adjusted, thereby realizing the control of the two-dimensional pointing angle of the microwave beam.

[0043] In this embodiment, the structures and principles of each optical switch are exactly the same. Figure 1 As shown in FIG. 8( e ), the optical switch is composed of two 2×2 multi-mode interferometers and a thermal phase shifter, but the present invention is not limited thereto. Figure 3 Schematic diagram of the control voltage of the thermal phase shifter loaded into the optical switch and the transmittance of the optical switch port according to an embodiment of the present invention.

[0044] Reference Figure 3 When the voltage is 0V, the light input from the input port in1 of the optical switch will be completely output from the output port out2, while the light input from the input port in2 of the optical switch will be completely output from the output port out1; when the voltage is 1.57V, the light input from the input port in1 of the optical switch will be completely output from the output port out1, while the light input from the input port in2 of the optical switch will be completely output from the output port out2. Therefore, by switching the voltage of 0V and 1.57V, it is controlled whether the laser passes through the long waveguides b5, b7 and b9, thereby realizing the control of the delay.

[0045] In this paragraph, in order to better illustrate the optical path, the device names before the reference numerals are omitted in the description of the optical path. In the on-chip modulator, the optical path a2→b1→b2→a3 is used to monitor whether the function of the Mach-Zehnder modulator b1 is operating normally. The optical path a4→b3→b4→b5→b6→b7→b8→b9→b10→b11 is used to monitor whether the function of the fourth photodetector b11 is operating normally.

[0046] In this paragraph, in order to better illustrate the optical path, the device names before each figure mark are omitted in the description of the optical path. Multiple single-wavelength lasers or broadband lights output by the off-chip light source are coupled into the chip through the eleventh grating coupler a11, and are input to the first input port of the first optical switch b4 through the optical waveguide. The optical signal passes through the optical path b4→b5→b6→b7→b8→b9→b10, and is finally output from the first output port of the fourth optical switch b10, and is input to the twelfth grating coupler a12 through the optical waveguide. The optical path a11→b4→b5→b6→b7→b8→b9→b10→a12 is used for system debugging to obtain the control power supply of the switching path of the optical switches b4, b6, b8 and b10, and is also used to monitor whether the optical switches b4, b6, b8 and b10 are operating normally. Similarly, the optical path a9→...→a10, the optical path a7→...→a8 and the optical path a5→...→a6 are used for system debugging to obtain the control power supply of the optical switch switching path and to monitor whether the optical switch operates normally.

[0047] Continue to refer to Figure 2 The optical transceiver coherent device c is used to receive the local oscillator laser signal and the laser signal to be demodulated (i.e., the laser signal loaded with the microwave signal), and demodulate the co-directional microwave signal and the orthogonal microwave signal according to the received local oscillator laser signal and the laser signal to be demodulated.

[0048] Specifically, the optical transceiver coherent device c includes: first and second 1×2 multimode interferometers c1 and c2, first and second thermal phase shifters c3 and c4, a crossover c5, first and second 2×2 multimode interferometers c6 and c7, and first and second balanced detectors c8 and c9.

[0049] The first 1×2 multimode interferometer c1 is used to receive a local oscillator laser signal and divide the received local oscillator laser signal into a first local oscillator laser signal and a second local oscillator laser signal. The second 1×2 multimode interferometer c2 is used to receive a laser signal to be demodulated and divide the received laser signal to be demodulated into a first laser signal to be demodulated and a second laser signal to be demodulated.

[0050] The first 2×2 multimode interferometer c6 is used to receive the first local oscillator laser signal through the first thermal phase shifter c3, and is used to receive the second laser signal to be demodulated through the crossover c5. The second 2×2 multimode interferometer c7 is used to receive the first laser signal to be demodulated through the second thermal phase shifter c4, and is used to receive the second local oscillator laser signal through the crossover c5.

[0051] The first balanced detector c8 is used to receive the first local oscillator laser signal and the second laser signal to be demodulated after being processed by the first 2×2 multimode interferometer c6. The second balanced detector c9 is used to receive the second local oscillator laser signal and the first laser signal to be demodulated after being processed by the second 2×2 multimode interferometer c7.

[0052] The phase difference between the local oscillator laser signal and the laser signal to be demodulated is adjusted by controlling the voltage of at least one of the first and second thermal phase shifters c3 and c4, so that the first and second balanced detectors c8 and c9 respectively output the demodulated co-directional microwave signal and the orthogonal microwave signal. The co-directional microwave signal and the orthogonal microwave signal can be output to the outside of the chip through the microstrip line and the radio frequency interface (and the radio frequency street connector connected thereto).

[0053] Specifically, the input port of the first 1×2 multimode interferometer c1 is connected to the 13th grating coupler to receive the local oscillator laser signal (for example, a single-wavelength laser signal) output by an off-chip light source, the first output port of the first 1×2 multimode interferometer c1 is connected to one end of the first thermal phase shifter c3, and the second output port of the first 1×2 multimode interferometer c1 is connected to the crossover c5.

[0054] The input port of the second 1×2 multimode interferometer c2 is connected to the 14th grating coupler to receive the laser signal to be demodulated, the first output port of the second 1×2 multimode interferometer c2 is connected to one end of the second thermal phase shifter c4, and the second output port of the second 1×2 multimode interferometer c2 is connected to the crossover c5.

[0055] The first input port of the first 2×2 multimode interferometer c6 is connected to the other end of the first thermal phase shifter c3, the second input port of the first 2×2 multimode interferometer c6 is connected to the crossover c5, and the first output port and the second output port of the first 2×2 multimode interferometer c6 are both connected to the first balanced detector c8.

[0056] The first input port of the second 2×2 multimode interferometer c7 is connected to the other end of the second thermal phase shifter c4, the second input port of the second 2×2 multimode interferometer c7 is connected to the crossover c5, and the first output port and the second output port of the second 2×2 multimode interferometer c7 are both connected to the second balanced detector c9.

[0057] Continue to refer to Figure 2 The optical phased array d includes: an on-chip dual parallel Mach-Zehnder modulator, a beam splitter, M thermal phase shifters d7 and M waveguide gratings d8.

[0058] The dual parallel Mach-Zehnder modulator is used to receive a microwave signal and a laser signal, and modulate the microwave signal onto the laser signal. The beam splitter is used to divide the modulated laser signal into M paths. The j-th thermal phase shifter and the j-th waveguide grating are used to sequentially allow the j-th modulated laser signal to pass through, 1≤j≤M. In this embodiment, M is 16, but the present invention is not limited thereto.

[0059] The phase difference between the laser signals radiated from the waveguide gratings is changed by controlling the voltage of each thermal phase shifter, thereby controlling the azimuth angle of the radiated laser signal.

[0060] Further, the dual parallel Mach-Zehnder modulator includes: a 1×2 multimode interferometer d1, a first and a second Mach-Zehnder modulator d2 and d3, a thermal phase shifter d4, and a first and a second 2×2 multimode interferometer d5 and d6.

[0061] The input port of the 1×2 multimode interferometer d1 is connected to the 17th grating coupler to receive the laser signal, the first output port of the 1×2 multimode interferometer is connected to the first input port of the first Mach-Zehnder modulator d2, and the second output port of the 1×2 multimode interferometer d1 is connected to the first input port of the second Mach-Zehnder modulator d3. In this way, the 1×2 multimode interferometer d1 splits the laser signal input through the 17th grating coupler into two, and provides them to the first and second Mach-Zehnder modulators d2 and d3 respectively.

[0062] The second input port of the first Mach-Zehnder modulator d2 is connected to the RF connector through a microstrip line and a RF interface to receive a microwave signal, and the output port of the first Mach-Zehnder modulator d2 is connected to one end of the thermal phase shifter d4. The first Mach-Zehnder modulator d2 modulates the microwave signal it receives onto the laser signal it receives to output the modulated laser signal.

[0063] The second input port of the second Mach-Zehnder modulator d3 is also connected to the RF connector through the microstrip line and the RF interface to receive the microwave signal, and the output port of the second Mach-Zehnder modulator d3 is connected to the second input port of the first 2×2 multimode interferometer d5. Similarly, the second Mach-Zehnder modulator d3 modulates the microwave signal it receives onto the laser signal it receives to output the modulated laser signal.

[0064] The first input port of the first 2×2 multimode interferometer d5 is connected to the other end of the thermal phase shifter d4, the first output port of the first 2×2 multimode interferometer d5 is connected to the first input port of the second 2×2 multimode interferometer d6, and the second output port of the first 2×2 multimode interferometer d5 is connected to the 16th grating coupler.

[0065] The second input port of the second 2×2 multimode interferometer d6 is connected to the 15th grating coupler, and the first output port and the second output port of the second 2×2 multimode interferometer d6 are both connected to the beam splitter d9.

[0066] Specifically, the beam splitter d9 includes three layers of fourteen 1×2 multimode interferometers, specifically including: two first 1×2 multimode interferometers, four second 1×2 multimode interferometers and eight third 1×2 multimode interferometers.

[0067] The input ports of the two first 1×2 multimode interferometers are connected to the output ports of the second 2×2 multimode interferometer d6, the input ports of the four second 1×2 multimode interferometers are connected to the output ports of the two first 1×2 multimode interferometers, the input ports of the eight second 1×2 multimode interferometers are connected to the output ports of this second 1×2 multimode interferometer, and the sixteen output ports of these eight second 1×2 multimode interferometers are respectively connected to a corresponding thermal phase shifter d7 and waveguide grating d8.

[0068] Therefore, the beam splitter d9 divides the light energy input to the second 2×2 multimode interferometer d6 into sixteen parts, and inputs them into sixteen completely identical thermal phase shifters d7 and waveguide gratings d8 respectively.

[0069] Specifically, by controlling the voltage of the sixteen-way thermal phase shifter d7, the phase difference between the near-infrared lasers radiated from the sixteen-way waveguide grating d8 can be changed respectively, thereby realizing the control of the azimuth angle of the laser beam. By changing the laser wavelength input to the optical phased array through the grating coupler a17, the elevation angle of the laser beam can be controlled. In this way, by controlling the two-dimensional angle of the laser beam, the laser information can be accurately sent to the receiver in free space, thereby realizing free space laser communication.

[0070] In this paragraph, in order to better illustrate the optical path, the device names before the reference numerals are omitted in the description of the optical path. The optical path a17→d1→d2(d3)→d4→d5→a16 is used to monitor whether the functions of the first and second Mach-Zehnder modulators d2 and d3 are operating normally. The optical path a15→d6→d7→d8 is used to monitor whether the functions of the thermal phase shifter d7 and the waveguide grating d8 are operating normally.

[0071] To sum up, in the transceiver chip according to the embodiment of the present invention, after debugging and monitoring of the optical path a2→b1→b2→a3, the optical path a11→b4→b5→b6→b7→b8→b9→b10→a12, the optical path a9→…→a10, the optical path a7→…→a8, the optical path a5→…→a6, the optical path a17→d1→d2(d3)→d4→d5→a16 and the optical path a15→d6→d7→d8, the microwave and infrared dual-band free space communication can work normally.

[0072] For example, a 5Gbaud-QPSK microwave signal with a microwave carrier frequency of 30GHz is input to the second input port of the Mach-Zehnder modulator b1 of the microwave beamforming network b through the RF connector and the microstrip line, and the microwave signal is modulated onto the laser signal. Finally, the microwave signal is output at the output port of the four-way photodetector b11 and transmitted to the free space through the array microwave antenna outside the chip to realize microwave communication. Figure 4is a constellation diagram after the microwave signal transmitted by the microwave beamforming network according to an embodiment of the present invention is received and demodulated. Figure 4 The error vector magnitude (EVM) of the demodulated microwave signal of 5Gbaud-QPSK with a carrier frequency of 30GHz is 29.73%.

[0073] For another example, a baseband 20Gbaud-16QAM microwave signal is input into the second input ports of the first and second Mach-Zehnder modulators d2 and d3 of the optical phased array through a RF connector and a microstrip line, the microwave signal is modulated onto a laser signal, and finally a laser beam is radiated from the chip surface into the free space at the position of the sixteen-way waveguide grating d8, thereby realizing laser communication. Figure 5 is a light spot diagram of the near-infrared band radiated by the optical phased array according to an embodiment of the present invention. Figure 5 ,The energy distribution of the light spot radiated by the optical phased array is very concentrated, and most of the energy is concentrated in the main lobe of the laser beam. Figure 6 1 is a constellation diagram after the laser signal radiated by the optical phased array according to the embodiment of the present invention is input into the optical coherent transceiver through the fourteenth grating coupler for demodulation. Figure 6 The EVM of the demodulated baseband 20Gbaud-16QAM microwave signal is 10.27%.

[0074] In summary, according to an embodiment of the present invention, a transceiver chip integrating a microwave beamforming network, an optical coherent transceiver and an optical phased array is provided. The transceiver chip is low-cost and highly compact, and can meet the rapidly growing demand for high-speed and broadband bandwidth for low-Earth orbit satellite-to-ground and inter-satellite communications.

[0075] The terms "exemplary," "example," and the like used throughout this specification mean "used as an example, instance, or illustration" and do not mean "preferred" or "advantageous" over other embodiments. The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques can be implemented without these specific details. In some instances, in order to avoid obscuring the concepts of the described embodiments, well-known structures and devices are shown in block diagram form.

[0076] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0077] The above description of the contents of this specification is provided to enable any person of ordinary skill in the art to implement or use the contents of this specification. Various modifications to the contents of this specification will be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of protection of the contents of this specification. Therefore, the contents of this specification are not limited to the examples and designs described herein, but are consistent with the widest range of principles and novel features disclosed herein.

Claims

1. A microwave and infrared dual-band free-space communication transceiver chip, characterized in that: The transceiver chip integrates a grating coupler array, a microwave beamforming network, an optical coherent transceiver and an optical phased array.

2. The transceiver chip according to claim 1, characterized in that: The microwave beamforming network includes: an on-chip modulator, N on-chip optical switch delay lines, and N photodetectors; The on-chip modulator is used to receive a microwave signal and receive a laser signal through the grating coupler array, modulate the microwave signal onto the laser signal, and output four modulated laser signals; The i-th on-chip optical switch delay line is used to adjust the delay of the i-th modulated laser signal; The i-th photoelectric detector is used to convert the i-th delayed laser signal into a microwave signal; Among them, 1≤i≤N.

3. The transceiver chip according to claim 2, characterized in that: The on-chip modulator includes: a Mach-Zehnder modulator, a first 1×2 multimode interferometer, a 2×2 multimode interferometer, a second 1×2 multimode interferometer, and a third 1×2 multimode interferometer; the grating coupler array includes a second grating coupler, a third grating coupler, and a fourth grating coupler; The first input port of the Mach-Zehnder modulator is connected to the second grating coupler for receiving a laser signal, the second input port of the Mach-Zehnder modulator is used to receive a microwave signal, the Mach-Zehnder modulator is used to modulate the microwave signal onto the laser signal, and the output port of the Mach-Zehnder modulator is used to output the modulated laser signal; The input port of the first 1×2 multimode interferometer is connected to the output port of the Mach-Zehnder modulator, and the first output port thereof is connected to the third grating coupler, and the second output port thereof is connected to the second input port of the 2×2 multimode interferometer; The first input port of the 2×2 multimode interferometer is connected to the fourth grating coupler, and the first output port thereof is connected to the input port of the second 1×2 multimode interferometer, and the second output port thereof is connected to the input port of the third 1×2 multimode interferometer; The first output port of the second 1×2 multimode interferometer is connected to the first on-chip optical switch delay line, the second output port of the second 1×2 multimode interferometer is connected to the second on-chip optical switch delay line, the first output port of the third 1×2 multimode interferometer is connected to the third on-chip optical switch delay line, and the second output port of the third 1×2 multimode interferometer is connected to the fourth on-chip optical switch delay line.

4. The transceiver chip according to claim 3, characterized in that: The i-th on-chip optical delay line includes: a first optical switch, a first long waveguide, a second optical switch, a second long waveguide, a third optical switch, a third long waveguide and a fourth optical switch; the grating coupler array also includes a 2i+3 grating coupler and a 2i+4 grating coupler; The first input port of the first optical switch is connected to the 2i+3th grating coupler, the second input port of the first optical switch is connected to the first output port of the second 1×2 multimode interferometer, the first output port of the first optical switch is connected to one end of the first long waveguide, and the second output port of the first optical switch is connected to the second input port of the second optical switch; The first input port of the second optical switch is connected to the other end of the first long waveguide, the first output port of the second optical switch is connected to one end of the second long waveguide, and the second output port of the second optical switch is connected to the second input port of the third optical switch; The first input port of the third optical switch is connected to the other end of the second long waveguide, the first output port of the third optical switch is connected to one end of the third long waveguide, and the second output port of the third optical switch is connected to the second input port of the fourth optical switch; The first input port of the fourth optical switch is connected to the other end of the third long waveguide, the first output port of the fourth optical switch is connected to the 2i+4th grating coupler, and the second output port of the fourth optical switch is connected to the i-th photodetector.

5. The transceiver chip according to claim 1, characterized in that: The optical transceiver coherent device is used to receive a local oscillator laser signal and a laser signal to be demodulated, and demodulate a co-directional microwave signal and an orthogonal microwave signal according to the received local oscillator laser signal and the laser signal to be demodulated.

6. The transceiver chip according to claim 5, characterized in that: The optical transceiver coherent device includes: first and second 1×2 multimode interferometers, first and second thermal phase shifters, a crossover, first and second 2×2 multimode interferometers, and first and second balanced detectors; The first 1×2 multi-mode interferometer is used to receive the local oscillator laser signal, and divide the received local oscillator laser signal into a first local oscillator laser signal and a second local oscillator laser signal; The second 1×2 multi-mode interferometer is used to receive the laser signal to be demodulated, and divide the received laser signal to be demodulated into a first laser signal to be demodulated and a second laser signal to be demodulated; The first 2×2 multi-mode interferometer is used to receive the first local oscillator laser signal through the first thermal phase shifter, and is used to receive the second laser signal to be demodulated through the crossover; The second 2×2 multi-mode interferometer is used to receive the first laser signal to be demodulated through the second thermal phase shifter, and is used to receive the second local oscillator laser signal through the crossover; The first balanced detector is used to receive the first local oscillator laser signal and the second laser signal to be demodulated after being processed by the first 2×2 multi-mode interferometer; The second balanced detector is used to receive the second local oscillator laser signal and the first laser signal to be demodulated after being processed by the second 2×2 multi-mode interferometer; The phase difference between the local oscillator laser signal and the laser signal to be demodulated is adjusted by controlling the voltage of at least one of the first and second thermal phase shifters, so that the first and second balanced detectors respectively output the demodulated co-directional microwave signal and orthogonal microwave signal.

7. The transceiver chip according to claim 6, characterized in that: An input port of the first 1×2 multimode interferometer is connected to the 2N+5th grating coupler to receive a local oscillator laser signal, a first output port of the first 1×2 multimode interferometer is connected to one end of the first thermal phase shifter, and a second output port of the first 1×2 multimode interferometer is connected to the crossover; The input port of the second 1×2 multimode interferometer is connected to the 2N+6th grating coupler to receive the laser signal to be demodulated, the first output port of the second 1×2 multimode interferometer is connected to one end of the second thermal phase shifter, and the second output port of the second 1×2 multimode interferometer is connected to the crossover; A first input port of the first 2×2 multimode interferometer is connected to the other end of the first thermal phase shifter, a second input port of the first 2×2 multimode interferometer is connected to the crossover, and a first output port and a second output port of the first 2×2 multimode interferometer are both connected to the first balanced detector; The first input port of the second 2×2 multimode interferometer is connected to the other end of the second thermal phase shifter, the second input port of the second 2×2 multimode interferometer is connected to the crossover, and the first output port and the second output port of the second 2×2 multimode interferometer are both connected to the second balanced detector; Wherein, N is the total number of on-chip optical switch delay lines of the microwave beamforming network.

8. The transceiver chip according to claim 1, characterized in that: The optical phased array comprises: an on-chip dual parallel Mach-Zehnder modulator, a beam splitter, M-channel thermal phase shifters and M-channel waveguide gratings; The dual parallel Mach-Zehnder modulator is used to receive a microwave signal and a laser signal, and modulate the microwave signal onto the laser signal; the beam splitter is used to split the modulated laser signal into M paths; the j-th thermal phase shifter and the j-th waveguide grating are used to sequentially allow the j-th modulated laser signal to pass through, 1≤j≤M; The phase difference between the laser signals radiated from the waveguide gratings is changed by controlling the voltage of each thermal phase shifter, thereby controlling the azimuth angle of the radiated laser signal.

9. The transceiver chip according to claim 8, characterized in that: The dual parallel Mach-Zehnder modulator comprises: a 1×2 multimode interferometer, a first and a second Mach-Zehnder modulator, a thermal phase shifter, and a first and a second 2×2 multimode interferometer; An input port of the 1×2 multimode interferometer is connected to the 2N+9th grating coupler to receive a laser signal, a first output port of the 1×2 multimode interferometer is connected to a first input port of a first Mach-Zehnder modulator, and a second output port of the 1×2 multimode interferometer is connected to a first input port of a second Mach-Zehnder modulator; The second input port of the first Mach-Zehnder modulator is used to receive a microwave signal, and the output port of the first Mach-Zehnder modulator is connected to one end of the thermal phase shifter; The second input port of the second Mach-Zehnder modulator is used to receive a microwave signal, and the output port of the second Mach-Zehnder modulator is connected to the second input port of the first 2×2 multi-mode interferometer; The first input port of the first 2×2 multimode interferometer is connected to the other end of the thermal phase shifter, the first output port of the first 2×2 multimode interferometer is connected to the first input port of the second 2×2 multimode interferometer, and the second output port of the first 2×2 multimode interferometer is connected to the 2N+8th grating coupler; The second input port of the second 2×2 multimode interferometer is connected to the 2N+7th grating coupler, and the first output port and the second output port of the second 2×2 multimode interferometer are both connected to the beam splitter; Wherein, N is the total number of on-chip optical switch delay lines of the microwave beamforming network.

10. The transceiver chip according to claim 8 or 9, characterized in that: The beam splitter comprises: M / 8 first 1×2 multimode interferometers, M / 4 second 1×2 multimode interferometers and M / 2 third 1×2 multimode interferometers; The input ports of the M / 8 first 1×2 multimode interferometers are all connected to the output ports of the 2×2 multimode interferometers, the input ports of the M / 4 second 1×2 multimode interferometers are all connected to the output ports of the M / 8 first 1×2 multimode interferometers, the input ports of the M / 2 second 1×2 multimode interferometers are all connected to the output ports of the M / 4 second 1×2 multimode interferometers, and the M output ports of the M / 2 second 1×2 multimode interferometers are respectively connected to corresponding thermal phase shifters.

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