Light driven optofluidic switch developed in a ZnO-overlaid microstructured optical fiber

In Vivo Optofluidic Switch for Controlling Blood Microflow

Control of blood microflow is crucial for the prevention and therapy of blood disorders, such as cardiovascular diseases and their complications. Conventional control strategies generally implant exogenous synthetic materials into blood vessels as labeling markers or actuating sources, which are invasive and incompatible with biological systems. Here, a label-free, noninvasive, and biocompatible device constructed from natural red blood cells (RBCs) for controlling blood microflow in vivo is reported. The RBCs, optically manipulated, arranged, and rotated using scanning optical tweezers, can function as an optofluidic switch for targeted switching, directional enrichment, dynamic redirecting, and rotary actuation of blood microflow inside zebrafish. The regulation precision of the switch is determined to be at the single-cell level, and the response time is measured as ≈200 ms using a streamline tracking method. This in vivo optofluidic switch may provide a biofriendly device for exploring blood microenvironments in a noncontact and noninvasive manner.

2 × 2 optofluidic switch chip with an air shutter

A 2×2 optofluidic switch chip with an air shutter is proposed. It has a simple structure, small volume, small crosstalk, large extinction ratio, small polarization-dependent loss, and broad operation waveband (400-1700 nm). This 2×2 switch chip has good scalability and can form a number of optical switches by using different microfluidic driving technologies. The research results show that the microchannel width has great influence on the switch performances in "on" state, where the comprehensive performances of the optical switch are the best at 4.0 μm width. By replacing the original symmetrical structure with an optimized semi-tapered structure, the switch performances are further improved. After the structure and parameters are optimized, for 1310 nm wavelength, the insertion losses of the proposed switch are 0.41 dB in "on" state and 0.15 dB in "off" state, the extinction ratios are 52.5 dB in "on" state and 28.3 dB in "off" state, and the crosstalks are -28.8  dB in "on" state and -52.6  dB in "off" state.

Optofluidic variable optical attenuator controlled by electricity

An optofluidic variable optical attenuator (VOA) is proposed in this paper, where the microfluidic driving technology adopts the electrically controlled way. The proposed driving technology solves some problems of existing microfluidic driving technologies and introduces a simple structure, a small volume, high precision, and a quick response for the VOA. This VOA has some advantages over other VOAs, such as a wide wavelength band (from visible light to the near infrared), a wide adjustable attenuation range, a low wavelength-dependent loss, and a quick response. The experiment results indicate that the attenuation range of this VOA is more than 80 dB and the wavelength-dependent loss is 0.09 dB at an attenuation of 20 dB in the C-band. Most VOAs have millisecond-scale response times, whereas the response time here is about 155-180 μs. Our work shows a new way to design miniaturized VOAs with good performance and can also promote optofluidics.

Application of Thin ZnO ALD Layers in Fiber-Optic Fabry-Pérot Sensing Interferometers

In this paper we investigated the response of a fiber-optic Fabry-Pérot sensing interferometer with thin ZnO layers deposited on the end faces of the optical fibers forming the cavity. Standard telecommunication single-mode optical fiber (SMF-28) segments were used with the thin ZnO layers deposited by Atomic Layer Deposition (ALD). Measurements were performed with the interferometer illuminated by two broadband sources operating at 1300 nm and 1550 nm. Reflected interference signal was acquired by an optical spectrum analyzer while the length of the air cavity was varied. Thickness of the ZnO layers used in the experiments was 50 nm, 100 nm, and 200 nm. Uncoated SMF-28 fiber was also used as a reference. Based on the results of measurements, the thickness of the ZnO layers and the length of the cavity were selected in order to achieve good visibility. Following, the interferometer was used to determine the refractive index of selected liquids.