THz-Tip: Near Field Photoconductive electric-field probe-tip
- Fig. 1.: Mounted THz probe-tip
AMO offers a new THz near-field sensor based on a novel microstructure design.
The freely-positionable photoconductive probe-tip enables low-invasive measurements of the amplitude and phase of a broadband electrical field within the THz frequency range.
The spatial resolution of the sensor is 5 µm within a frequency range from 100 GHz to 3 THz which translates into a sub-wavelength resolution of up to lambda/600. The THz near-field probe has been developed at RWTH Aachen University (Institute for Semiconductor Technology) for error detection and design assistance of THz and microwave devices such as antennas, waveguides or integrated circuits.
Details on the performance of the THZ-Tip can be found in the following publication: “Tapered photoconductive terahertz field probe tip with subwavelength spatial resolution“, M. Wächter, M. Nagel, and H. Kurz, Appl. Phys. Lett 95, 041112 (2009).
Please visit also our THz-Technology pages for more information about THz Measurement and Applications.
Applications
- Fig. 2.: 2D near field amplitude distribution on coplanar waveguide measured with THz tip
- Time resolved terahertz near-field microscopy (THz-SNOM)
- On-chip micro wave integrated (MMIC) testing
- Radar / HF antenna near-field testing
- THz time- and frequency-domain spectroscopy
- Near- & far-field broadband THz detection
Key features
- Patend pending design
- Tapered electrodes for field-singularity enhanced sensitivity
- PC probe-tip with unprecedented near-field spatial resolution (5µm)
- Low-invasive probing through ultra-thin (1.3 µm) probe design
- Easy to integrate into existing optical systems (cw or pulsed)
- Convenient tip-sample approximation through probe mounting with
built-in tilt angle - Versatilely applicable for near- and far-field measurements
- Polarisation sensitive (10:1)
Utilisation example
- Fig. 3: Setup
The Thz-Tip is mainly dedicated to be used in fs second pump probe experiments. Figure 3 illustrates a typical setup where a THz radiation is sampled by the THz-Tip which is gated by the fs second probe beam.
Other configuration to measure in reflection, synchronized to HF devices in near- or far-field are possible as well.
Best results, especially in THz imaging, are optained using a fast sampling technique like AMO´s AixScan technology utilising fast delay lines, ASOPS or ECOPS as a faster alternative to lock-in amplifiers with superior noise reduction also for low frequency noise.
Technical Data
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Specifications
- Fig 4.: Typical current-voltage characteristics
- Fig. 5: Typical THz field amplitude detected in the far-field
Test conditions:
- Optical source: Ti:Sa oscillator at λ = 800 nm,
TFWHM = 150 fs and frep= 80 MHz - THz emitter: InAs surface field emitter, excitation power P = 300 mW.
- THz detector: Thz-Tip, excitation power P = 3 mW
- Lock-in detection with mechanical chopper at 1.5 kHz and 100 ms integration time in ambient air
Schematic
- Fig.6: Schematic
Pictures
Fig. 7.: Mounted THz probe-tip
(article no.: THz-tip)
Fig. 8.: Mounted THz probe-tip with translation and focusing
mechanics for free-space excitation on a magnetic
baseplate
(article no.: THz-tip+Mount free1)
Fig. 9.: Mounted THz probe-tip with translation and focusing
mechanics for fiber-coupled excitation on a magnetic
baseplate
(article no.: THz-tip+Mount fiber1)
Order Information
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| on request |
| on request |
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