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SATURN Transient RecorderAixScan: Acquisition for Ultrafast SpectroscopyTHz Nearfield Microscopy
THz Nearfield Microscopy

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 electric 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 this recent publication: “Tapered photoconductive terahertz field probe tip with subwavelength spatial resolution“, M. Wächter, M. Nagel, and H. Kurz, Appl. Phys. Lett 95, 041112 (2009).

 

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
  • Polarization sensitivitve (10:1)


Utilisation example

Fig. 3: Setup

The Thz-Tip is mainly dedicated to be used in fs second pump probe experiments. The 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, too.

Best results, especially in THz imaging, are optained using a fast sampling technique like AMO´s AixScan technology utilizing fast delay lines, ASOPS or ECOPS as a faster alternative to lock-in amplifiers with superior noise reduction also for low frequeny noise.

 

Technical Data



Minimum


Standard


Maximum


Gap size at apex [µm]

 1,5

3

4,5


Spatial resolution [µm] @100 GHz - 3 THz


5




Dark resistivity [MΩ]


50


100



Photocurrent ratio Ipower/Idark (UBias = 1 V, P = 5 mW)

5e4

1e5



Bias [V]



1


1,5


Excitation wavelength [nm]


700


800


850


Excitation power (λ=800 nm, frep = 80 MHz, τFWHM = 150 fs) [mW]



5


10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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


THz-tip 
   

2.500 €


THz tip+Mount free1

                                             

3.900 €


THz-tip+Mount fiber1

4.100 €


Discount:
 

  • 10% for 3-5 pieces
  • 20% for more than 6 pieces
  • Note:                                           
    Each delivered device is tested to insure optimal
     results                                                          

 

 

 

 

 

 

 

 

 

 

 

 

 

More Information: