30th Annual Report 2017-18

159 The laser will act as a carrier and the audio is given as a modulating signal to the solenoid, the audio signal modulated in the presence of Faraday material (TGG) and demodulated by converting polarization modulation into intensity modulation at the photo detector. The power requirement is very low as compare to the existing analogue modulation techniques. The system is successfully working over the audio bandwidth. Radio Physics Lab Radio Physics Lab (RPL) is a unique facility at IUCAA, where students from physics and engineering background can explore their skills and learn Astronomy and Astrophysics. Our aim has been to design and demonstrate important experiments related to Radio Astronomy in an innovative way for scientific purpose and for educating students, enthusiasts and general public. The areas being pursued here range from cosmic ray detection to communication using LASERs. Apart from this, RPL is also active in public outreach. Public lectures and demonstrations are organized for students and enthusiasts. RadioAstronomy Winter School (RAWS) is conducted for undergraduate students introducing them to the field of Radio Astronomy. Over the past 10 years several students have been benefited from this platform. More than 90 percent of students are pursuing PhD in astronomy and related areas and many are currently active in research field in some formor the other. Following are the details of experiments and activities carried out by RPL. FaradayRotationExperiment forCommunication The polarization of light is quite frequently observed in nature, and with other properties like amplitude, frequency and phase of an electromagnetic (EM) wave, it constitutes one of the most fundamental quantities, which completely describes it. In Physics and Optics, the polarization of light is studied through ”Faraday Rotation Effect” using optical materials like glass, crystals, chemicals, etc. Its analogue in radio waves is transmission of polarized wave in ferrites materials. The idea is to study the potential of fast polarization modulation for data communication, which is not much explored yet. The study of polarization of light through Faraday Rotation Effect, rotation of plane of polarized wave when traveling through crystals placed inside solenoid; subjected to a strong axial magnetic field can be a novel approach in communication. Experiment shows conversion of polarization-modulated light into intensity-modulated light, and phase shifted demodulated wave form w.r.t. input modulating signal. Insertion of properlymatched and tuned circuit before coil and amplifier after demodulation leads to better reception of signal. Experiments