All-optical tuning of a magnetic-fluid-filled optofluidic ring resonator

Abstract

An all-optical tunable optofluidic ring resonator (OFRR) is proposed and experimentally demonstrated. The all-optical control of a silica microresonator is highly attractive, but it is difficult to realize because of the relatively weak Kerr effect and the absence of a plasma dispersion effect of silica. Here, we infuse a silica microcapillary-based optofluidic ring resonator with a magnetic fluid, into which pump light is injected by a fiber taper. Iron oxide nanoparticles dispersed in the magnetic fluid produce a strong pump light absorption, and this leads to a resonance shift of the silica microresonator due to the photothermal effect. To the best of our knowledge, this is the first scheme for all-optical tuning of an OFRR. A tuning sensitivity of up to 0.15 nm mW(-1) and a tuning range of 3.3 nm are achieved. With such excellent performance, the magnetic-fluid-filled OFRR has great potential in filtering, sensing, and signal processing applications.

Laser-tuned whispering gallery modes in a solid-core microstructured optical fibre integrated with magnetic fluids

“…where ξ and α refer to thermo-optic and thermal expansion coefficients, respectively, and their values are 8.3 × 10 −6 and 0.55 × 10 −6 for silica material; and are respectively defined as initial effective refractive index and effective radius before the pump laser is injected into the MFIMOF; η refers to the correlation coefficient between temperature and pump laser power, which depends on the absorption coefficient and thermal conductivity of the MFs as well as geometry of the MOF 20 33 . If the wavelength dependences of and are taken into account, the power-tuning sensitivity of particular WGM could be expressed as:…”

“…The WGM microresonators could be classified into versatile categories, including microdisk 11 , microring 12 , microsphere 13 , microbottle 14 and capillary 15 , etc. Amongst these structures, due to their applicability for microfluidic applications and ease of being integrated with functional materials, open-cavity microresonators, such as microbottles and capillaries, have attracted growing research interests in developing photonic components with more intriguing functionalities for various applications, including fluidic bio-/chemical sensing 5 16 17 , localized laser excitation 18 19 , and field-dependent photonic devices 20 .…”

Laser-Induced Thermal Effect for Tunable Filter Employing Ferrofluid and Fiber Taper Coupler

“…As the pump light power changes, the average RI variation of the MFs around the taper region could be expressed as [19]:…”

“…However, their applicability for practical uses is limited owing to the high optical absorption that leads to strong laser-induced thermal effect. It provides a simple but effective approach to achieve all-optically controlled devices [19].…”

Propriedades ópticas não lineares de segunda e terceira ordem de coloides magnéticos

“…Assim, novos dispositivos e funcionalidades podem ser desenvolvidas [9], como fibrasópticas com núcleo preenchido por líquidos [10] para aplicações em sensoreamento biológico [11]. Uma vez que coloides magnéticos combinam as propriedades de fluidez do líquido carregador e as propriedades magnéticas das nanopartículas, o uso de ferrofluidos em dispositivos optofluídicos tem promovido grandes inovações, como por exemplo o desenvolvimento de fibrasópticas revestidas por ferrofluidos [12,13], cristais fotônicos coloidais [14] e microrressonadores de silício recobertos com coloides magnéticos [15,16], casos em que as propriedades magnéticas das nanopartículas exercem um papel importante no controle das propriedadesópticas dos dispositivos. Além disso, magnetômetrosópticos [17,18] e sensores de campo magnético [19,20] baseados em nanopartículas magnéticas foram desenvolvidos, além de chavesópticas [21] reconfiguráveis [22] e ajustáveis [23], limitadoresópticos [24,25] e absorvedores saturáveis [26,27].…”