Context:
Telecom Regulatory Authority of India (TRAI) released a “Consultation Paper on Open and De-licensed use of Unused or Limited Used Spectrum Bands for Demand Generation for Limited Period in Tera Hertz Range”.
About THR:
- It is a region of electromagnetic spectrum in range of 100 GHz to 10 THz (between millimetre and infrared frequencies).
- It lies on the cusp (transition point) of electronics and photonics.
- Region on frequency spectrum where electronic and photonics technologies do not meet is called the Terahertz gap (0.3 to 30 THz).
- It is also referred to as a sub-millimetre, far-infrared, and near-millimetre wave.
Properties of THR:
- Penetration: THz waves have less scattering and better penetration depths against infrared waves. Therefore, dry, and non-metallic materials, which are opaque in the visible spectrum, are transparent THR.
- Resolution: Gives a better spatial imaging resolution as THz waves have shorter wavelengths against microwaves.
- Safety: THz radiation is non-ionizing and their photon energies are much lower than X-ray.
Applications of THz:
- Space-based communication like Earth Exploration-Satellite Service (EESS), radio astronomy service, etc.
- Short-range wireless communication.
- Security applications (like solid explosive material detection).
- Biomedical imaging and body surface diagnoses.
Challenges:
- Lack of efficient, coherent, and compact THz sources and detectors.
- THz waves exhibit high losses due to high atmospheric absorption.
- Their signal degradation is considerably more partly because the water molecules resonate in this range.
Source: PIB
Previous Year Question
With reference to Visible Light Communication (VLC) technology, which of the following statements are correct?
1. VLC uses electromagnetic spectrum wavelengths 375 to 780 nm.
2. VLC is known as long-range optical wireless communication.
3. VLC can transmit large amounts of data faster than Bluetooth.
4. VLC has no electromagnetic interference.
Select the correct answer using the code given below:
[UPSC Civil Services Exam – 2020 Prelims]
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 1, 3 and 4 only
(d) 2, 3 and 4 only
Answer: (c)
Explanation:
The nature of light is that it is unable to pass through opaque walls. Hence, VLCT is used in indoor environment/short range. Hence statement 2 is not correct.
