TERA8 THz-Antennas - Menlo Systems - #1

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TERA8 THz Generation THz-ANTENNAS FOR 800 nm Photoconductive switch optimized for lasers around 800 nm and pulse width <150 fs 6 dipole structures on each chip Low temperature (LT) grown GaAs dipole structure We test each device and include the individual test report in the shipment Features Test Conditions for Data Plots Optical source: fs fiber laser operating at 780 nm and 130 fs pulse width Data recorded with 20 ìm dipole used on emitter and detector side Mechanical chopper with 1 kHz Lock-in detection with 30 ms integration time 10 mW of optical input power at emitter and detector side Up to 45 V bias for emitter The Tera8 comprises six dipole structures on one single chip. With the “6 in 1” approach highest bandwidth and highest sensitivity on one chip become reality. Each chip can be used as emitter or as detector. Make no compromise in performance and flexibility! We bring Tera8 to the market with our collaborator the IPM, the Fraunhofer Institute for Physical Measurement Techniques IPM. The THz region of the electromagnetic spectrum lies between the microwave and the infrared part. THz waves are of major interest in spectroscopy, quality control and security applications. Photoconductive switches are used as emitters and detectors for THz radiation. Simply illuminate the antenna with femtosecond optical pulses and get THz waves. A photoconductive antenna, e.g. a low temperature grown GaAs layer with metallic contacts can be used as an optical excited broadband terahertz emitter. Typically, an alternating voltage is supplied to the contacts to allow a lock-in measurement. Two important antenna parameters are the dipole length and the gap distance of the antenna structure. The dipole length determines the preferred emitted frequency at the resonance condition. Typically, a silicon lens aligned with the antenna is used to increase the extraction efficiency for the THz waves. THz Detection The detector has a similar or even exactly same design as the emitter. The optimal gap between the metallic contacts is about equal to the laser spot diameter. A current amplifier connected to the detector contacts delivers a signal proportional to the terahertz electric field strength. Fraunhofer Institut Physikalische Messtechnik IPM THE SOLUTION FOR FREE-SPACE THz SYSTEMS Amplitude [a.u.] Frequency [THz] 0.0 1.0 2.0 3.0 4.0 5.0 1 0.1 10 100 15 20 25 30 0.0 50 25 -50 -25 75 100 Time [ps] Amplitude [a.u.] Spectrum of emitted THz radiation (insert shows data plot of electrical field as function of time)