CN104466337A - Terahertz signal coupling device - Google Patents

Abstract

A terahertz signal coupling device proposed by the present invention includes a quasi-optical cavity composed of a horn antenna with a rectangular waveguide as a port and a plane mirror, and is placed at the antinode of the standing wave of the quasi-optical cavity to obtain the maximum and uniform coupling strength. The chip of the terahertz array element. The chip is prepared with a crystal material as a substrate, and as a dielectric resonator, its resonance mode and resonance frequency are determined through electromagnetic field simulation; an array of integrated terahertz array elements is prepared at the antinode of the resonant standing wave on the center line of the chip, with To obtain the maximum coupling strength; use the matching of the resonant mode of the chip as a dielectric resonator and the resonant mode of the quasi-optical cavity formed by the horn antenna and the plane mirror to realize the effective coupling of the terahertz array element on the chip and the waveguide transmission line. The invention solves the problem of high-efficiency coupling of integrated array elements on a chip and conventional microwave transmission lines in engineering applications.

Description

Terahertz signal coupling device

technical field

The invention relates to a terahertz transmission device that combines quasi-optical principles to realize ultra-broadband tunable terahertz transmission devices, and is especially suitable for devices that couple integrated array elements in terahertz frequency bands with conventional microwave transmission lines such as waveguides.

Background technique

The terahertz frequency band is a very valuable electromagnetic wave frequency band for scientific research. It is between the millimeter wave frequency band and the infrared frequency band, and belongs to the far infrared band. In addition to key components such as terahertz radiation sources, terahertz transmission devices, and terahertz detectors, the application of terahertz must also solve the coupling problem between different devices. Since the emission, reflection and transmission spectra of substances in the terahertz frequency band contain rich physical and chemical information, and terahertz waves have unique properties such as short wavelength, good directionality, low photon energy, and high penetration, terahertz waves Technology has gradually become a hot spot in international research. It is used in basic research fields such as physics, chemistry, astronomy, life science and medicine, as well as in fields such as safety inspection, nondestructive testing, biological imaging, environmental monitoring, food inspection, environmental monitoring, medical diagnosis, radar reconnaissance, satellite communication and astronomical observation, etc. Applied research fields have great scientific research value. At this stage, terahertz radiation sources generally have problems such as low power and low efficiency; moreover, the thermal background noise is relatively high, and high-sensitivity means are needed to detect terahertz signals, so the efficient transmission and coupling of terahertz waves is proposed. higher requirement. For the transmission and reception of terahertz signals, the transmission power or reception sensitivity can be greatly improved by building an array. At the same time, in view of the short wavelength of the terahertz frequency band, generally on the order of submillimeters, high-density integration of large-scale array elements can be realized, and hundreds or thousands of array elements can be integrated on one chip. However, how to achieve effective coupling between integrated array elements and conventional microwave transmission lines has become a difficult problem that needs to be solved urgently.

At present, the coupling methods widely used in the terahertz frequency band can be roughly divided into two categories, one is to extend the conventional microwave coupling method to the terahertz frequency band; the other is to apply the quasi-optical energy coupling method to the terahertz frequency band. For the first type of method, in order to realize the effective coupling between the array element on the chip and the transmission line such as waveguide, methods such as waveguide microstrip transition and coplanar antenna are often used. However, as the frequency increases, the loss of the conventional substrate and the surface loss of the metal increase rapidly; at the same time, due to the short wavelength of the high-frequency band, it is difficult to achieve the machining accuracy of the microstrip and the metal cavity. Therefore, the first type of method is often limited to the sub-sub-Hz frequency band, that is, the 0.1 THz-1 THz frequency band. For the second type of method, quasi-optical methods such as parabolic mirrors and lenses are often used to rationally design the optical path to achieve effective coupling of energy. This method can cover the entire terahertz frequency band, but is usually used in the 1THz-10THz frequency band. Moreover, how to achieve effective coupling of multiple array elements in a large-scale array on the chip, especially to ensure phase synchronization; and how to be perfectly compatible with conventional microwave transmission lines have not yet been reasonably resolved. Therefore, in the terahertz frequency band, it is still a difficult problem in engineering applications to realize the efficient coupling of on-chip integrated array elements and conventional microwave transmission lines.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the above-mentioned prior art, and provide a simple structure, easy processing and realization, easy operation and tuning, ultra-wide operating frequency, high coupling strength, good phase synchronization, and can be integrated on the chip. Large-scale array array elements and waveguides achieve effective coupling, improving the efficiency of terahertz signal transmission and reception, especially applicable to the entire 0.1THz to 10THz terahertz frequency band, and the coupling frequency and coupling strength are adjustable for terahertz signal coupling device.

The above object of the present invention can be achieved through the following technical solutions, a terahertz signal coupling device, including a horn antenna with a rectangular waveguide as a port and a quasi-optical cavity formed by a plane mirror, and placed at the antinode of the quasi-optical cavity resonant standing wave , to obtain a chip with maximum and uniform coupling strength integrated with a terahertz array element, which is characterized in that: the chip is prepared on a crystal material as a dielectric resonator, and its resonant mode and resonant frequency are determined through electromagnetic field simulation; the integrated terahertz array element The array is prepared at the antinode of the resonant standing wave on the center line of the chip to obtain the maximum coupling strength; using the matching of the resonant mode of the chip as a dielectric resonator and the resonant mode of the quasi-optical cavity formed by the horn antenna and the plane mirror, To realize the effective coupling between the on-chip terahertz array element and the waveguide transmission line.

Compared with the prior art, the present invention has the following beneficial effects:

The structure is simple, easy to process and easy to operate. The present invention uses a horn antenna with a rectangular waveguide as a port and a quasi-optical cavity composed of a plane mirror, and places a chip integrated with a terahertz array element at the antinode of its resonant standing wave, making full use of the resonant mode of the chip as a dielectric resonator Matching with the resonant mode of the quasi-optical cavity formed by the horn antenna and the plane mirror to realize the effective coupling of the terahertz array element on the chip and the waveguide transmission line, the components used are few, the structure is simple, the quasi-optical system is simple, and the manufacturing process requirements are low. It is easy to process and easy to operate, which solves the problems of high manufacturing process requirements, difficult practical application, difficult processing and the like in the prior art.

Easy to operate and tune, wide working frequency. In the invention, the integrated array element is placed at the centerline position of the chip, so that it is simultaneously in the antinodes of multiple resonant modes on the chip. By adjusting the relative positions of the chip, the plane mirror and the horn antenna, the different resonant modes of the chip are respectively matched with the corresponding resonant modes of the quasi-optical cavity, and the working frequency can be adjusted. Moreover, the terahertz chip uses a crystal material with low high-frequency loss, low dielectric constant, and thin thickness as the substrate, so that even in the terahertz frequency band, the chip can have multiple simple resonant modes, which are easy to combine with quasi-optical cavity resonant modes. Matching and covering a wide frequency range. It solves the problem that the coupling frequency point of the integrated array element on the chip and the conventional microwave transmission line is single and difficult to tune in engineering applications.

The coupling strength is high and the strength can be tuned. The invention can realize high-efficiency coupling of array elements and waveguides integrated in a large-scale array on a chip, and improves the efficiency of transmitting and receiving terahertz signals. When the resonant mode of the chip perfectly matches the resonant mode of the quasi-optical cavity, the effective coupling between the terahertz array element integrated on the chip and the waveguide port is realized. Experimental results show that its coupling efficiency is improved by dozens of times compared with the method used in the prior art. At the same time, the coupling strength can be easily tuned by adjusting the relative positions of the chip, the plane mirror and the horn antenna, which is difficult to achieve in the prior art.

Good phase synchronization. The present invention combines the quasi-optical method, fully utilizes the matching of the resonant mode of the chip as a dielectric resonator and the resonant mode of the quasi-optical cavity formed by the horn antenna and the plane mirror, to realize the effective coupling of the terahertz array element on the chip and the waveguide transmission line, And the large-scale array elements integrated on the chip are in the antinode of the same chip resonance mode, and the phase coupling with the waveguide transmission line is synchronized, which solves the problem that the conventional quasi-optical system is difficult to operate due to the complex optical path design Synchronous coupling with multiple array elements in a large-scale array, inconvenient compatibility with conventional microwave transmission lines, etc.

The present invention is particularly suitable for the entire terahertz frequency band of 0.1THz to 10THz, and is a terahertz signal coupling device with adjustable coupling frequency and coupling strength.

Description of drawings

Fig. 1 is an exploded schematic view of the terahertz signal coupling device of the present invention.

In the figure: 1 rectangular waveguide, 2 horn antenna, 3 chip, 4 plane mirror.

Detailed ways

The present invention will be further described below in combination with a terahertz signal detection system based on a zero-voltage biased Schottky diode series array.

See Figure 1. In a preferred embodiment described below, the terahertz signal coupling device includes a horn antenna 2 with a rectangular waveguide 1 as the port, a quasi-optical cavity formed by a plane mirror 4, and a chip 3 prepared with a terahertz array element. The chip itself acts as a dielectric resonator. Chip 3 is prepared on a high-resistance silicon substrate by using semiconductor micromachining technology to prepare a series array of Schottky diodes and electrodes for zero-voltage bias. The resonance mode and resonance frequency of the chip as a dielectric resonator are determined by electromagnetic field simulation. And the array is placed at the center antinode of the resonant standing wave of the chip, that is, the center line of the chip, so that multiple resonant modes can be selected, so as to realize tunable working frequency, that is, work at the resonant frequency point. The integrated array element of the terahertz chip is a device with terahertz signal generation and detection performance; the array structure can be series, parallel, or any other structure. The terahertz chip uses a crystal material with low high-frequency loss, low dielectric constant, and thin thickness as the substrate, so that even in the terahertz frequency band, the chip can have multiple simple resonance modes, which are easy to match with quasi-optical cavity resonance modes. And cover a wide frequency range.

Using a horn antenna 2 and a plane mirror 4 to form a quasi-optical cavity, the resonant mode of the above-selected operating frequency is obtained through electromagnetic field simulation to determine the distance between the horn antenna and the plane mirror and the antinode position of the resonant standing wave. The distance between the waveguide port of the horn antenna and the plane mirror should be an integer multiple of the half wavelength of the working frequency. At the same time, the chip 3 integrated with the terahertz array element is placed at the antinode of the quasi-cavity resonant standing wave, and the distance between the antinode and the plane mirror is the (N/2+1/4) wavelength of the operating frequency (N = 0, 1,2,…) to obtain maximum and uniform coupling strength.

When the relative positions of the horn antenna 2, the plane mirror 4 and the chip 3 are determined according to the above description, the chip resonant mode will perfectly match the quasi-cavity resonant mode. The terahertz signal to be measured is fed through the rectangular waveguide port 1 of the horn antenna 2, which will definitely excite the resonant standing wave of the quasi-optical cavity formed by the horn antenna 2 and the plane mirror 4. Since the resonant mode of the chip 3 also matches the resonant mode of the quasi-optical cavity, the resonance of the chip 3 as a dielectric resonant cavity will also be excited. The series array composed of Schottky diodes of the terahertz signal detection element is located at the center amplitude of the resonant standing wave of the chip 3, and can receive the terahertz signal to be measured with uniform energy and phase synchronization, thus realizing the waveguide port 1 and Efficient coupling of array elements in series array on chip 3. At the same time, from the electrodes on the chip 3, the phase-synchronous voltage signals induced by the array elements of the zero-voltage biased Schottky diode series array can be read out, so that its detection sensitivity is significantly higher than that of a single Schottky diode. improve.

Claims (6)

1. A terahertz signal coupling device, including a quasi-optical cavity formed by a horn antenna with a rectangular waveguide as a port and a plane mirror, and placed at the antinode of the quasi-optical cavity resonant standing wave to obtain the maximum and uniform coupling strength. Integrated terahertz The chip of the array element is characterized in that: the chip is prepared with a crystal material as a substrate, and as a dielectric resonator, its resonance mode and resonance frequency are determined through electromagnetic field simulation; the array of integrated terahertz array elements is prepared on the center line of the chip to resonate. The antinode of the wave to obtain the maximum coupling strength; use the matching of the resonant mode of the chip as a dielectric resonator and the resonant mode of the quasi-optical cavity formed by the horn antenna and the plane mirror to realize the on-chip terahertz array element and waveguide transmission line effective coupling. 2. The terahertz signal coupling system as claimed in claim 1, characterized in that: the resonant mode and resonant frequency of the chip as the dielectric resonator are determined by electromagnetic field simulation, and the terahertz array element is placed in the resonant standing wave of the chip The center antinode, that is, the center line of the chip, enables multiple resonant modes to be selected, so as to realize tunable working frequency, that is, work at the resonant frequency point. 3. The terahertz signal coupling device according to claim 2, characterized in that: the terahertz signal to be measured is fed through the rectangular waveguide port (1) of the horn antenna (2), and the horn antenna (2) and the plane mirror ( 4) The resonance of the formed quasi-optical cavity and the resonance of the chip (3) as a dielectric resonator. 4. The terahertz signal coupling device according to claim 1, characterized in that: the horn antenna is axially connected to the rectangular waveguide as the port, and the plane mirror (4) is parallel to the chip (3), facing the horn of the horn antenna At the end, the chip (3) is located between the quasi-optical cavity formed by the plane mirror and the horn antenna. 5. The terahertz signal coupling device according to claim 2, characterized in that: the array element of the terahertz array is located at the center antinode of the resonant standing wave of the chip (3), realizing the connection between the waveguide port (1) and the chip (3) Efficient coupling of array elements in the upper array. 6. The terahertz signal coupling device according to claim 1, characterized in that: the integrated array element of the terahertz chip is a device capable of generating or detecting terahertz signals; the array structure can be serial or parallel, and other arbitrary structures.