Preparation method of high-sensitivity terahertz sensor

Abstract

The present disclosure provides a high-sensitivity terahertz sensor. The high-sensitivity terahertz sensor includes a substrate; a metal microstructure array, including a plurality of metal microstructure units, and covering the substrate to form a metasurface; and metal nanostructures, located at gaps of the metal microstructure array, where the metal microstructure array and the metal nanostructures are formed by etching a metal film on the substrate through pulsed laser direct writing. The present disclosure utilizes the metasurface and the metal nanostructures to cooperatively enhance the terahertz wave, promoting full interaction between the terahertz wave and the analyte and improving terahertz detection sensitivity.

Claims

1. A preparation method of a high-sensitivity terahertz sensor, wherein the high-sensitivity terahertz sensor comprises: a substrate; a metal microstructure array, comprising a plurality of metal microstructure units, and covering the substrate to form a metasurface; and metal nanostructures, located at gaps of the metal microstructure array; the preparation method comprising: step 1: adjusting parameters of pulsed laser, comprising a laser power density of 1 mJ/cm2, a pulse width of 10 ns, and a wavelength of 1064 nm; step 2: focusing the pulsed laser onto a surface of a silver film; and step 3: adjusting a scanning path of the pulsed laser according to a shape of a metal microstructure for processing with a laser scanning speed of 10 mm/s, such that the metal film on the scanning path of the pulsed laser melts to form the metal nanostructures under a surface tension.

2. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein laser processing parameters are changed to form the metal nanostructures with different shapes, sizes, and densities.

3. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein laser processing parameters in different regions are changed to achieve different spatial distribution states of the metal nanostructure array.

4. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein a size of the plurality of metal microstructure units ranges from a micron order to a sub-millimeter order, and a shape of the plurality of metal microstructure units is designed arbitrarily.

5. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein a size of the metal nanostructures ranges from a nanometer order to a sub-micron order, and the metal nanostructures are designed arbitrarily.

6. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein the metal microstructure array is made of a component comprising gold or silver.

7. The preparation method of the high-sensitivity terahertz sensor according to claim 1, wherein the metal nanostructures are made of a component comprising gold or silver.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a preparation method of a high-sensitivity terahertz sensor according to an embodiment of the present disclosure;

(2) FIG. 2 is a schematic diagram of a high-sensitivity terahertz sensor according to Embodiment 1 of the present disclosure;

(3) FIG. 3 is a schematic diagram of a high-sensitivity terahertz sensor according to Embodiment 2 of the present disclosure; and

(4) FIG. 4 is a schematic diagram of a high-sensitivity terahertz sensor according to Embodiment 3 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) To make the above objectives, features, and advantages of the present disclosure more apparent and easily understood, the specific implementations of the present disclosure are described in detail below in conjunction with the drawings. The following describes many details in order to provide a thorough understanding of the present disclosure. However, the present disclosure can be implemented in many other different ways, and those skilled in the art can make similar improvements without departing from the connotation of the present disclosure. Therefore, the present disclosure is not limited to the specific implementations disclosed below.

(6) According to an embodiment of the present disclosure, a high-sensitivity terahertz sensor includes a substrate, a metal microstructure array, and metal nanostructures. The metal microstructure array includes a plurality of metal microstructure units and covers a substrate. The metal nanostructures are located at gaps of the metal microstructure array. The metal microstructure array forms a metasurface to achieve localized enhancement of a terahertz wave. The metal nanostructures located at the gaps of the microstructure array further enhance a local terahertz field strength. Ultimately, the design utilizes the metasurface and the metal nanostructures to cooperatively enhance the terahertz wave, promoting full interaction between the terahertz wave and the analyte and improving terahertz detection sensitivity.

(7) The sensor has a metal film etched on the substrate through pulsed laser direct writing, thereby conveniently preparing metal microstructure arrays and nanostructures of different shapes. Specifically, a preparation method of a high-sensitivity terahertz sensor according to an embodiment of the present disclosure includes the following steps. A metal film on a substrate is scanned with laser to form a metal microstructure array. The metal microstructure array includes a plurality of metal microstructure units. By controlling a laser parameter, the metal film in a region where a scanning path passes through melts and dewets to form metal nanostructures under a surface tension.

(8) Furthermore, by changing a laser processing parameter, the metal nanostructures with different shapes, sizes, and densities are formed. By changing laser parameters in different regions, different spatial distribution states of the metal nanostructure array are achieved.

(9) Furthermore, the laser has a power density of 10 J/cm.sup.2 to 100 mJ/cm.sup.2, a pulse width of 10 ps to 500 ns, and a wavelength of 200 nm to 1,700 nm.

(10) Furthermore, a size of the metal microstructure unit ranges from a micron order to a sub-millimeter order, and a shape of the metal microstructure unit is designed arbitrarily. A size of the metal nanostructure ranges from a nanometer order to a sub-micron order, and the metal nanostructure is designed arbitrarily. The metal microstructure array is made of a component including gold or silver. The metal nanostructure is made of a component including but not limited to gold or silver. A shape of the metal nanostructure includes but is not limited to a spherical shape, a radial shape, a polyhedral shape, a linear shape, etc.

Embodiment 1

(11) A thickness of a silicon substrate is 300 m, and a thickness of a silver film on the silicon substrate is 10 nm.

(12) A preparation method for a high-sensitivity terahertz sensor specifically includes the following preparation steps.

(13) Step 1. A parameter of a pulse laser is adjusted, including a laser power density of 1 mJ/cm.sup.2, a pulse width of 10 ns, and a wavelength of 1,064 nm.

(14) Step 2. A pulsed laser is focused onto a surface of the silver film.

(15) Step 3. A pulsed laser path is adjusted according to a shape of a metal microstructure for processing with a laser scanning speed of 10 mm/s.

(16) The metal film on the laser scanning path melts to form a uniform nano-metal structure under a surface tension, resulting in a sensor structure shown in FIG. 2. The metal microstructure has a line width of 5 m, a gap spacing of 5 m, and a period of 200 m. The metal nanostructure has an average diameter of 80 nm and covers an entire metasurface.

(17) A content of chlorothalonil was measured by the sensor. An experimental result demonstrates that the sensor can detect a minimum of 10 ng of chlorothalonil. In comparison, the minimum detection capacity of a terahertz metasurface sensor prepared by photolithography and lacking a nanostructure for synergistic enhancement is about 1 g. Therefore, the sensor sensitivity of the present disclosure is improved by about 100 times.

Embodiment 2

(18) A thickness of a silicon substrate is 300 m, and a thickness of a silver film on the silicon substrate is 10 nm.

(19) A preparation method for a high-sensitivity terahertz sensor specifically includes the following preparation steps.

(20) Step 1. A parameter of a pulse laser is adjusted, including a laser power density of 100 J/cm.sup.2, a pulse width of 15 ps, and a wavelength of 1,064 nm.

(21) Step 2. A pulsed laser is focused onto a surface of the silver film.

(22) Step 3. A pulsed laser path is adjusted for processing with a scanning speed of 100 mm/s. The metal film completely peels off on the laser scanning path.

(23) Step 4. The parameter of a pulse laser is adjusted, including a laser power density of 1 mJ/cm.sup.2, a pulse width of 10 ns, and a wavelength of 1,064 nm. The pulsed laser path is adjusted for processing with a scanning speed of 30 mm/s. The metal film on the laser scanning path melts to form a uniform nano-metal structure under a surface tension.

(24) Thus, a sensor structure shown in FIG. 3 is formed. The metal microstructure has a line width of 5 m, a gap spacing of 5 m, and a period of 200 m. The metal nanostructure has an average diameter of 80 nm and covers a metasurface locally.

(25) Through the above process, a content of chlorothalonil was measured by the sensor. An experimental result demonstrates that the sensor can detect a minimum of 23 ng of chlorothalonil. In comparison, the minimum detection capacity of a terahertz metasurface sensor prepared by photolithography and lacking a nanostructure for synergistic enhancement is about 1 g. Therefore, the sensor sensitivity of the present disclosure is improved by about 43 times.

Embodiment 3

(26) A thickness of a silicon substrate is 300 m, and a thickness of a silver film on the silicon substrate is 20 nm.

(27) A preparation method for a high-sensitivity terahertz sensor specifically includes the following preparation steps.

(28) Step 1. A parameter of a pulse laser is adjusted, including a laser power density of 3 mJ/cm.sup.2, a pulse width of 10 ns, and a wavelength of 1,064 nm.

(29) Step 2. A pulsed laser is focused onto a surface of the silver film.

(30) Step 3. A pulsed laser path is adjusted for processing with a scanning speed of 100 mm/s. The metal film completely peels off on the laser scanning path.

(31) Step 4. The parameter of a pulse laser is adjusted, including a laser power density of 3 mJ/cm.sup.2, a pulse width of 10 ns, and a wavelength of 1,064 nm. The pulsed laser path is adjusted for processing with a scanning speed of 50 mm/s. The metal film on the laser scanning path melts to form a uniform nano-metal structure under a surface tension.

(32) Thus, a sensor structure shown in FIG. 4 is formed. The metal microstructure has a line width of 5 m, a gap spacing of 5 m, and a period of 200 m. The metal nanostructure has a diameter of 200 nm. The laser parameter is controlled to change the diameter of the metal nanostructures. The metal nanostructures cover the entire surface.

(33) Through the above process, a content of chlorothalonil was measured by the sensor. An experimental result demonstrates that the sensor can detect a minimum of 75 ng of chlorothalonil. In comparison, the minimum detection capacity of a terahertz metasurface sensor prepared by photolithography and lacking a nanostructure for synergistic enhancement is about 1 g. Therefore, the sensor sensitivity of the present disclosure is improved by about 13 times.

(34) The above embodiments are merely some implementations of the present disclosure. Although the description is specific and detailed, it should not be construed as a limitation to the patent scope of the present disclosure. It should be noted that those of ordinary skill in the art can further make several variations and improvements without departing from the concept of the present disclosure, and all these variations and improvements fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure is subject to the appended claims.