# US 2014/0197425 A1 · Wide area array type photonic crystal photomixer for generating and detecting broadband terahertz wave > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197425 A1 - Document ID: US20140197425A1 - Status: Published application - Kind: A1 - Application number: 14/154,717 - Filed: 2014-01-14 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Kiwon MOON; Han-Cheol RYU; Sang-Pil HAN; Kyung Hyun PARK - Web page: https://patentgrep.com/patent/US20140197425A1 ## CPC - H10F 55/00: Radiation-sensitive semiconductor devices covered by groups H10F10/00, H10F19/00 or H10F30/00 being structurally associated with electric light sources and electrically or optically coupled thereto - B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals - G02F 2/002: {using optical mixing} - H04B 10/90: Non-optical transmission systems, e.g. transmission systems employing non-photonic corpuscular radiation - H10F 77/1248: {having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP} - H10F 77/413: {directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42)} - G01N 21/3581: using far infrared light; using Terahertz radiation - G01N 21/3586: by Terahertz time domain spectroscopy [THz-TDS] - G02F 1/0126: {Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass} - G02F 2202/12: photoconductor - G02F 2202/32: Photonic crystals - G02F 2203/13: involving THZ radiation - H10W 90/00: Package configurations - Y02E 10/544: Solar cells from Group III-V materials - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - H04B: TRANSMISSION - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract Provided is a broadband photomixer technology that is a core to generate continuous frequency variable and pulsed terahertz waves. It is possible to enhance light absorptance by applying the transmittance characteristic of a 2D light crystal structure and it is possible to increase the generation efficiency of terahertz waves accordingly. Moreover, it is possible to implement a wide area array type terahertz photomixer by applying an interdigit structure and spatially properly arranging a light crystal structure having various cycles. Accordingly, it is possible to solve difficulty in thermal characteristic and light alignment by mitigating the high light density of a light absorption unit and low photoelectric conversion efficiency is drastically improved. In addition, the radiation pattern of terahertz waves may be electrically controlled through the present invention. ## Claims ### Claim 1 A photoconductive switch comprising: a first electrode coupled to a first level of voltage; a second electrode coupled to a second level of voltage; and a photonic crystal formed between the first and second electrodes over of the photoconductive layer formed on a substrate, the photonic crystal having a plurality of unit metal cell arrays arranged at preset distances. ### Claim 2 (depends on 1) The photoconductive switch of claim 1, wherein the unit metal cell array includes at least four metal cells that are arranged at preset distances in first and second directions. ### Claim 3 (depends on 2) The photoconductive switch of claim 2, wherein the sectional shape of the metal cell is one of a circle, a polygon including a triangle, and a cross. ### Claim 4 (depends on 2) The photoconductive switch of claim 2, wherein the preset distance is formed to make a symmetrical grating structure or an asymmetrical grating structure. ### Claim 5 (depends on 2) The photoconductive switch of claim 2, wherein the preset distances and arrangement cycles of the plurality of unit metal cell arrays vary in the design process to allow the generation of terahertz waves to be adjusted. ### Claim 6 (depends on 1) The photoconductive switch of claim 1, wherein when the first electrode is an anode, the second electrode is a cathode. ### Claim 7 (depends on 1) The photoconductive switch of claim 1, wherein when the second electrode is an anode, the first electrode is a cathode. ### Claim 8 (depends on 1) The photoconductive switch of claim 1, wherein the photoconductive layer is formed of a GaAs material. ### Claim 9 (depends on 1) The photoconductive switch of claim 1, wherein the photoconductive layer is formed of an InGaAs material or an InGaAsP material. ### Claim 10 (depends on 1) The photoconductive switch of claim 1, wherein the photoconductive layer is a multi-layer thin film that includes a layer formed of an InGaAs material and a layer formed of an InAlAs material. ### Claim 11 A wide area array type photonic crystal photomixer comprising: a sub photomixer array comprising: a plurality of first electrode spaced apart from each other side by side and coupled to a bias voltage; a second electrode arranged between the first electrodes and coupled to a ground level; a first photonic crystal that is formed between the upper one of the first electrodes and the second electrode over the photoconductive layer formed on a substrate and that includes a plurality of first unit metal cell arrays arranged at preset distances; and a second photonic crystal that is formed between the lower one of the first electrodes and the second electrode over the photoconductive layer and that includes a plurality of second unit metal cell arrays arranged at preset distances. ### Claim 12 (depends on 11) The wide area array type photonic crystal photomixer of claim 11, wherein the first photonic crystal is used as a light absorption area. ### Claim 13 (depends on 12) The wide area array type photonic crystal photomixer of claim 12, wherein the second photonic crystal is used as a light reflection area. ### Claim 14 (depends on 13) The wide area array type photonic crystal photomixer of claim 13, wherein sizes of the first and second unit metal cell arrays are different. ### Claim 15 (depends on 14) The wide area array type photonic crystal photomixer of claim 14, wherein a size of the first unit metal cell array is smaller than a size of the second unit metal cell array. ### Claim 16 (depends on 11) The wide area array type photonic crystal photomixer of claim 11, wherein a number of the sub photomixer array is three to form one large photomixer. ### Claim 17 (depends on 16) The wide area array type photonic crystal photomixer of claim 16, wherein the sub photomixer array has an interdigitated (IDT) structure in which the first and second electrodes are alternately arranged, when forming the one large photomixer. ### Claim 18 (depends on 11) The wide area array type photonic crystal photomixer of claim 11, wherein the photoconductive layer is formed by using a low temperature growth technique. ### Claim 19 A method of manufacturing a photoconductive switch for a photomixer, the method comprising: forming a buffer layer on a substrate; forming a photoconductive layer on the buffer layer; forming a photonic crystal pattern including a plurality of unit metal cell arrays that are arranged at preset distances on the photoconductive layer; and forming first and second electrodes that electrically control light absorptance and light reflectivity on the photoconductive layer by the photonic crystal pattern. ### Claim 20 (depends on 19) The method of claim 19, wherein the photonic crystal pattern is manufactured as a light reflection area and a light absorption area.