Tunable optical switch using magnetic fluids

Abstract

With a tunable refractive index, magnetic fluid can be applied to the development of adjustable optical devices. In this work, a magnetic-fluid-based optical switch is designed and characterized. The optical switch is formed by sealing magnetic fluid between two glass prisms. When a light is incident to one side of one of the prisms, a reflected light from the magnetic fluid film comes out from the same prism, whereas a transmitted light through the film emits from the other prism. It was found that the intensity ratio of the reflected light to the transmitted light can be manipulated by varying the external magnetic field strength. This implies that the light intensity can be switched between two paths. The switching efficiency also depends on the incident angle of a light into the prism. We then theoretically derive the incident-angle dependent switching efficiency to clarify relevant physical mechanisms.

Facile hydrothermal synthesis of polyhedral Fe3O4 nanocrystals, influencing factors and application in the electrochemical detection of H2O2

“…As one of the representative magnetic materials, magnetite (Fe 3 O 4 ) always attracts extensive research interest in materials science due to its low producing cost, environmental benignity, interesting magnetic behaviors, and widely potential applications in drug-delivery, gas sensors, magnetic filters, electrode materials, magnetic storage media, and microwave-absorbing materials [13][14][15][16][17][18][19][20]. Many methods have been developed for the preparation of magnetite nanoparticles, including coprecipitation of Fe 2+ and Fe 3+ ions in alkaline solutions [21], ultrasound assisted preparation [22], thermal decomposition of Fe(acac) 3 precursor [23], polyol route [24], hydrothermal process [25,26] and solvothermal technique [27,28].…”

Fiber-optic evanescent field modulator using a magnetic fluid as the cladding

“…At the same time, the refractive index of the MF will increase with the strength of the magnetic field. So the index difference between the fiber and the MF will reduce, and then more evanescent field is guided in the MF, 25 which can be seen in Fig. 4.…”

Microsecond-scale switching time of magnetic fluids due to the optical trapping effect in waveguide structure

“…The amplitude of S z in the guiding layer is enhanced by 68 times than that in the air before coupling into the DMCW structure. As was pointed out by Deng et al (2008), Horng et al (2004), Dai et al (2010), the clustering of magnetic nanoparticles will be resolved at large power densities and resulting in a rapid agglomeration when an external field is applied. However, as will be clarified later, apart from high energy density, large-scale optical trapping effect inside the guiding layer may be the primary reason for the rapid agglomeration of nanoparticles.…”

“…However, the mechanisms governing the dynamics are still ambiguous, which cause the research on the response time of chain formation play an important role on the further application. A number of reports have pointed out that the agglomeration rate of magnetic nanoparticles is usually in second scale (Deng et al 2008;Horng et al 2004;Dai et al 2010) or even in minute scale (Li et al 2007(Li et al , 2002. In addition, it is also demonstrated that a finite retardation exists between the switch on/off of the external field and the variation of the transmission through the ferrofluid films, and this corresponding retarding time ranges from several to tens of milliseconds, depending on the field strength .…”