The microprobe series TeraSpike is the new generation of high-performance microprobes for the photo-conductive detection of electric fields in the THz frequency range. Surface-near electric THz fields can now be measured with unprecedented signal quality and low invasiveness. The microprobes seamlessly fit into systems with optical excitation wavelengths below 860 nm and are the most cost-efficient solution to turn an existing time-domain pump/probe-system into a powerful THz near-field system for high-resolution imaging.
In addition to custom-specific microprobes (please inquire) the following standard models are offered for pulsed excitation:
Electrical connection is done through a compact coaxial SMP plug. We recommend the use of a low-noise current amplifier with 107-108 V/A amplification (e.g. DLPCA200) and high-grade connection cables (e.g. our TS Cable) for optimum operation.
The microprobes from the new 1550-X-series are our first probes which can be directly sampled by telecom-wavelength (1500 .. 1600 nm) laser pulses. They are sensitive to electric vector field-components oriented in transversal direction to the probe-tip axis as defined by the x-axis direction in the upper illustration. The model TD-1550-X-HR-WT offers good spatial resolution and clean spectral response due to our patent-pending internal absorber ("wave-trap") structures. The model TD-1550-X-HR-WT-XR provides increased mechanical robustness with only moderate loss of spatial resolution and sensitivity. It is designed for rougher applications e.g. where the sample distance is more difficult to control.
|Max. spatial resolution||40 µm (20 µm(#))||80 µm|
|Photo-switch gap size||1.5 µm||1.5 µm|
|Dark current @ 1 V Bias||< 4.5 µA||< 4.5 µA|
|Photocurrent @ 1 V Bias||> 12 µA (*)||> 12 µA (*)|
|Excitation wavelength||1500 .. 1600 nm|
|Average excitation power||1.5 .. 3.5 mW|
(*) For a focus diameter of circa 20 µm, bias voltage 1 V , average optical excitation power 3 mW.
(#) For front-switch instead of main-switch excitation. Front-switch excitation mode is showing reduced SNR.
|Max. spatial resolution||8µm||8µm|
|Photo-switch gap size||2µm||5µm|
|Dark current @ 1 V Bias||< 0.4 nA||< 0.4 nA|
|Photocurrent @ 1 V Bias||>0.1 µA||> 0.5 μA|
|Excitation wavelength||700 .. 860 nm||700 .. 860 nm|
|Average excitation power||0.1 .. 4 mW||0.1 .. 4 mW|
Z-series microprobes are sensitive to THz field components oriented in longitudinal direction to the probe-tip axis as defined by the z-axis direction in the upper illustration. The N-option does not include a resonant antenna element and provides a somewhat higher bandwidth. The A-500G-option includes an antenna element for enhanced sensitivity around 0.5THz.
The new TeraSpike model TR.5 comes with a pair of closely spaced photoconductive THz antennas offering new means for high-performance near-field measurements in reflection-mode. While one antenna is used as a radiation pulse generator, the other antenna is used as the detector. The slim transceiver probe is taking advantage of Protemics´ proprietary “wave-trap” design for the suppression of probe-internal reflection signals as well as the XR-type flexible PET cantilever design for increased mechanical robustness. In contrast to standard reflection-mode approaches based on far-field emitter/detector components the new near-field transceiver probe provides access to sub-wavelength-resolution and shortest THz transmissions paths.
|Dark current @ 1 V Bias||< 1.5 nA|
|Photocurrent @ 1 V Bias||> 0.5 µA|
|Excitation wavelength||700 .. 860 nm|
|Average excitation power||0.1 .. 4 mW|
|Connection type||2x SMP|
The TeraSpike TD-1550-Y-BF is a microprobe emitter based on patent pending design (DE 10 2013 020 216.7) for the bias-free surface-near excitation of Terahertz pulses on planar waveguides, metallic surfaces or meta-materials. The optically generated THz field is polarized in y-direction.
Configuration: THz pulse generation on a thin-film microstrip line using the bias-free TeraSpike emitter microprobe. For on-chip contact-free THz field detection a second TeraSpike probe from the TD-800-X or Z series can be applied.
THz Emission scheme: THz pulse generation is based on optical excitation of the InGaAs micro-cantilever surface. Placing the excited tip close to a conductive structure or surface allows efficient capacitive coupling and pulse transmission.
|Excitation wavelength||700 .. 1600 nm|
|Average excitation power||0.1 .. 4 mW|
|Emission bandwidth (for 90 fs pulse excitation)||> 2.5 THz|
This kit is the ideal solution to start with. It includes the following components:
With this set the orientation of the mounted TeraSpike microprobe can be freely chosen as required by the application. The use of the dummy device TeraSpike Phantom - as included in the starter kit - is recommended during all mechanical set-up and construction works because the risk of an uncontrolled mechanical impact during such processes can be easily avoided. Each microprobe is delivered in a robust transport and storage box.
The standard design of the TeraSpike probe is optimized for highest spatial resolution, lowest field invasiveness and highest sensitivity. This is achieved through the free-standing semiconductor-based cantilever microstructure containing the active field sensor elements. The mechanical robustness of this standard design matches the requirements of long-term application in well controlled and automated systems such as the TeraCube Scientific allowing also pointed sample contact.
For application in rougher environments or where the sample distance is more difficult to control the new XR-design is an excellent choice with drastically further increased mechanical robustness combined with only low reduction of spatial resolution and sensitivity.
The XR-option is currently available for the following x- and z-field sensitive TeraSpike probes:
If you are interested in an XR-option for other TeraSpike models, please contact us.
TeraSpike near-field probes are used under different excitation conditions. Some configurations might generate THz modes which are able to propagate along the internal electrodes of the probe-tip. So far, these modes were observed in terms of reflection signals in the recorded time-domain transients.
Protemics has developed a new patent pending design* called “wavetrap” which is effectively slowing down and absorbing such probe-internal THz signal transmission.
The WT-option is currently available for the following x- and z-field sensitive TeraSpike probes:
If you are interested in an WT-option for other TeraSpike models, please contact us.
*German patent application DE 10 2014 015 516.1