Experimental investigation of longitudinal magneto-optic effects in four ferrite ferrofluids in visible-near infrared spectrum

We present an extensive experimental work concerning measurement of longitudinal magneto-optic effects (Faraday rotation and circular dichroism) induced in magnetic liquids. Seven ferrofluid samples allow the study of the influence of numerous parameters: magnetic suspension and carrier liquid characteristics, magnetic field strength (up to 10 kOe) and frequency (dc to 50 kHz), light wavelength (400 to 2000 nm) and, temperature (253 to 373 K). These topics, especially the spectral area, have rarely been studied before. Most of the studies show interesting behaviors and aid in the understanding of magneto-induced phenomena. They also contribute to the conception of new optical applications of ferrofluids: 1) a pure Faraday rotator (free of circular dichroism) obtained by a ferrofluid mixing method and 2) a Faraday light modulator working up to 50 kHz.