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Journal ArticleDOI

Distinctive optofluidic parallel waveguides

Lip Ket Chin1, Yuanjun Yang1, L. Lei1, Ai Qun Liu1 
01 Jan 2014-Procedia Engineering (Elsevier)-Vol. 87, pp 1549-1552

AbstractNovel lightwave propagation and bending can be realized in optofluidics by designing the refractive index profile in the microchannel through diffusion via transformation optics. Diffusion in the microfluidic channel is controllable, tunable and reconfigurable, realizing sophisticated bidirectional gradient-index profile for light manipulation. In this paper, 3D optofluidic parallel waveguides are formed using Dean's flow in a microchannel with tunable nano-gap. Photon-tunneling is observed between the optofluidic waveguides, and due to the diffusion process, distinctive light propagation patterns are observed. In symmetrical waveguides, chirped coupling pattern is observed due to the relaxation in index contrast at the downstream. With the ease of changing the composition of the liquids, asymmetrical waveguides can be realized and complex leaky lightwave is observed. The demonstrated optofluidic parallel waveguides will open new doors for more sophisticated and elegant photonic elements such as Eaton lens, designing via transformation optics.

Topics: Optofluidics (54%), Refractive index profile (51%)

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Journal ArticleDOI
Abstract: This paper describes the design and operation of a liquid-core liquid-cladding (L2) lens formed by the laminar flow of three streams of liquids in a microchannel whose width expands laterally in the region where the lens forms. Two streams of liquid with a lower refractive index (the cladding) sandwich a stream of liquid with a higher refractive index (the core). As the core stream enters the expansion chamber, it widens and becomes biconvex in shape, for some rates of flow. This biconvex fluidic element focuses light. Manipulating the relative rates of flow of the streams reconfigures the shape, and therefore the focal distance, of the L2 lens. This paper also describes a technique for beam tracing, and for characterization of a lens in an enclosed micro-scale optical system. The use of a cladding liquid with refractive index matched to that of the material used in the fabrication of the microfluidic system (here, poly(dimethylsiloxane)) improves the quality of the focused beam.

183 citations


Journal ArticleDOI
TL;DR: It is shown that a laminar liquid flow in an optofluidic channel exhibits spatially variable dielectric properties that support novel wave-focussing and interference phenomena, which are distinctively different from the discrete diffraction observed in solid waveguide arrays.
Abstract: Transformation optics represents a new paradigm for designing light-manipulating devices, such as cloaks and field concentrators, through the engineering of electromagnetic space using materials with spatially variable parameters. Here we analyse liquid flowing in an optofluidic waveguide as a new type of controllable transformation optics medium. We show that a laminar liquid flow in an optofluidic channel exhibits spatially variable dielectric properties that support novel wave-focussing and interference phenomena, which are distinctively different from the discrete diffraction observed in solid waveguide arrays. Our work provides new insight into the unique optical properties of optofluidic waveguides and their potential applications.

149 citations


"Distinctive optofluidic parallel wa..." refers background in this paper

  • ...Recently, optofluidic waveguide with bidirectional gradient index profile, designed via transformation optics, is demonstrated to effectively bend and manipulate lightwave in a microfluidic flow [8]....

    [...]


Journal ArticleDOI
Abstract: This letter reports the measurement of single living cell’s refractive index (RI) using the optical grating resonant cavity with buffer modulation on a biochip. The cell’s RI is a significant cell biophysical property which has potential in cancer and disease diagnoses. The single cell is trapped optically within the cavity, and the transmission spectra shift due to the change of surrounding buffer, without/with cell, are used to determine the cell’s effective RI and effective thickness. The measurement shows that Madin-Darby canine kidney cell has an effective RI of 1.383±0.001. Moreover, the optical trapping technique eliminates uncertainty and avoids cell damage.

68 citations


"Distinctive optofluidic parallel wa..." refers background in this paper

  • ...In the last decade, optofluidics, exploiting the synergy between liquids and light, is used to develop tunable and reconfigurable optical elements, such as liquid microlenses [1-2], prisms [3], gratings [4-6], resonators [7] etc....

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Journal ArticleDOI
TL;DR: A novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating that has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids.
Abstract: This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.

62 citations


"Distinctive optofluidic parallel wa..." refers background in this paper

  • ...In the last decade, optofluidics, exploiting the synergy between liquids and light, is used to develop tunable and reconfigurable optical elements, such as liquid microlenses [1-2], prisms [3], gratings [4-6], resonators [7] etc....

    [...]


Journal ArticleDOI
Abstract: This letter reports the tunable liquid microlens using three laminar flows injected into an expansion chamber. Different lens shapes and curvatures can be achieved and tuned through the control of three flow rates. The expansion chamber is designed to improve the fluidic stability and maintain the ideal lens shape for precise microscale optical measurement. The optical aberration is also eliminated by minimizing the diffusive broadening at the interfaces. The collimation and focusing capabilities of three liquid microlenses are demonstrated. The tunable liquid microlens is promising as a tool to realize different optical components that can be integrated onto a microchip.

58 citations


"Distinctive optofluidic parallel wa..." refers background in this paper

  • ...In the last decade, optofluidics, exploiting the synergy between liquids and light, is used to develop tunable and reconfigurable optical elements, such as liquid microlenses [1-2], prisms [3], gratings [4-6], resonators [7] etc....

    [...]