Tunable optofluidic birefringent lens

Abstract

An optofluidic birefringent lens is demonstrated using hydrodynamic liquid-liquid (L(2)) interfaces in a microchannel. The L(2) lens comprises a nematic liquid crystal (NLC) phase and an optically isotropic phase for the main stream and the surrounding sub-stream, respectively. When the optofluidic device is subjected to a sufficiently strong electric field perpendicular to the flow direction, NLCs are allowed to orient along the external field rather than the flow direction overcoming fluidic viscous stress. The characteristics of the optofluidic birefringence lens are investigated by experimental and numerical analyses. The difference between the refractive indices of the main stream and the sub-stream changes according to the polarization direction of incident light, which determines the optical behaviour of the lens. The incidence of s-polarized light leads to a short focal point, while p-polarized light has a relatively long focal distance from the same L(2) interface. The curvatures and focal lengths of the lens are successfully evaluated by a hydrodynamic theory of NLCs and a simple ray-tracing model.

Manipulation and analysis of an optofluidic multiphase microlens

“…S1 † in the ESI). 6,9 The experimental results showed that the tunable focal length between 1.60 mm and 3.15 mm could be manipulated in the microuidic device fabricated in this study, as presented in Fig. 5(c).…”

“…Design and fabrication of the optouidic chip An optouidic device was fabricated using a so-lithography process with polydimethyl-siloxane (PDMS, Sylgard 184, Dow Corning, Midland, U.S.A.). A detailed process of fabricating a master is explained elsewhere, 9 and a cured PDMS replica from the master was attached to the glass substrate by corona treatment. The device consisted of a ow channel, aperture channels, and a ray-tracing chamber.…”

“…4 The optouidic microlens has emerged as a promising optical component due to its advantages over the solid microlens, e.g., wide tunable range and optically smooth interfaces by means of the hydrodynamic tuning mechanism, the ease in changing optical properties with different lens materials, and the simple fabrication and integration of the device. Recently, a few studies have demonstrated the tunable optouidic microlens using liquid-liquid [5][6][7][8][9] or gas-liquid interfaces. 10,11 They have shown considerable performance in experiments and carried out uid simulation to analyze the lens shape according to the microchannel geometry or ow conditions.…”

Optofluidic Tunable Lenses for In-Plane Light Manipulation

“…The refractive lens and the GRIN lens are often independent of the polarization and the wavelength of the incident light due to the use of isotropic and low-dispersion liquids (e.g., water, ethanol, ethylene glycol). In addition, there are some other lenses that aim at polarization separation or wavelength selection, such as birefringent liquid lens [ 31 ] and diffractive optofluidic lens [ 32 ]. For example, liquid crystal (LC) has been used to construct a polarization-dependent liquid lens [ 31 ].…”

Tunable‐focus negative poly(vinyl chloride) gel microlens driven by unilateral electrodes

“…In order to get advantages of compactness, cost, efficiency, and flexibility, close attention has been recently paid to developing variable‐focus lenses for electronic devices, such as cell phones, cameras, eyes of robots, and so on. A variable‐focus lens can be achieved by controlling the curvature of the interface between two fluids or the surface of a liquid . A variable‐focus lens can be also implemented by changing the local refractive index of material, the case of liquid crystals, for example.…”