Nano Terahertz Micro-Spectroscopy System
Terahertz (THz) radiation lies between infrared and microwaves; broadly defined, it occupies the 0.1–10 THz (30–3000 μm) region of the electromagnetic spectrum and remains a frequency band awaiting full exploration by researchers. A typical terahertz time-domain spectroscopy (THz-TDS) system covers an effective spectral range of 0.1–3 THz, right at the heart of the terahertz band, making it an excellent tool for terahertz research. The unique sampling method of TDS captures the time-domain signal of terahertz pulses, revealing rich physical information about the sample under test. However, the position of terahertz waves in the spectrum also means that far-field imaging resolution is limited to the scale of hundreds of micrometers, which severely restricts its applications — especially the study of terahertz responses of materials and structures at micro- and nano-scales. A THz near-field microscopy system is an outstanding solution for breaking through this limitation.
The tip of an atomic force microscope (AFM) can strongly confine terahertz waves between the tip and the sample. This confined (near) field can be localized to a region comparable to the tip diameter, so extracting this near field yields terahertz resolution comparable to the tip radius. Acting as an antenna, the probe radiates this near field into free space, while the oscillation of the probe in tapping mode modulates the radiated near field — therefore the near-field signal can be recovered simply by demodulating the signal received in the far field.
Product Highlights
The nanoTHz Nano Terahertz Micro-Spectroscopy System from Chengdu Miji Technology adopts a brand-new optical design that efficiently extracts the terahertz signal from the probe tip, delivering an ultra-high spatial resolution of 50 nm while maintaining an excellent signal-to-noise ratio — performance comparable to leading products worldwide.
- Spatial resolution better than 50 nm;
- Compatible with commercial AFM probes;
- Stable system, easy to operate;
- Stable signal and short imaging time;
- Vacuum-chuck sample stage for convenient sample loading and removal;
- Near-field imaging single-scan measurement volume: 10×10×15 mm;
- Equipped with a 5-megapixel CCD camera with spatial resolution better than 0.8 μm,
- Diagonal field of view greater than 700 μm.
Nano Terahertz Micro-Spectroscopy System Specifications
| High-resolution closed-loop scanner | XY ≥ 5 μm, Z ≥ 2 μm |
| Large-range closed-loop scanner | XY ≥ 100 μm, Z ≥ 5 μm |
| Noise level | XY < 0.2 nm, Z < 0.6 Å |
| Optical assistant module | High-resolution CCD optical observation system imaging on the computer, used to view the probe and sample; field of view between 1.25 mm and 0.25 mm with software-controlled automatic zoom; optical resolution < 2 μm; bundled control and imaging software |
| Scan mode | Sample scanning: an XYZ three-axis closed-loop scanner drives the sample, which sits below the probe. The area above the probe is completely unobstructed, making it easy to observe the sample with an optical microscope and position the measurement spot |
| Terahertz signal-to-noise ratio | 1st order: > 200 2nd order: > 80 Observable orders: > 7 |
| THz-TDS | 0.5–2 THz time-domain spectrum + femtosecond optical pulse width < 90 fs + far-field effective spectral range 0.1–3 THz + terahertz delay line measurement range 600 ps + near-field effective spectral range 0.5–2 THz |
The system includes the following parts:
- A scattering-type scanning near-field optical microscope (s-SNOM) optimized for terahertz, infrared and visible near-field microscopy;
- An integrated terahertz time-domain spectrometer based on a femtosecond pulsed laser source for near-field THz-TDS spectroscopy;
- A near-field imaging system suited to scattering-type scanning near-field microscopy.