Liquid-infiltrated photonic crystals: Ohmic dissipation and broadening of modes

The pronounced light-matter interactions in photonic crystals make them interesting as opto-fludic "building blocks" for lab-on-a-chip applications. We show how conducting electrolytes cause dissipation and smearing of the density-of-states, thus altering decay dynamics of excited bio-molecules dissolved in the electrolyte. Likewise, we find spatial damping of propagating modes, of the order dB/cm, for naturally occurring electrolytes such as drinking water or physiological salt water.Comment: 9 pages including 2 figure

Highly dispersive photonic band-gap-edge optofluidic biosensors

Highly dispersive photonic band-gap-edge optofluidic biosensors are studied theoretically. We demonstrate that these structures are strongly sensitive to the refractive index of the liquid, which is used to tune dispersion of the photonic crystal. The upper frequency band-gap edge shifts about 1.8 nm for dn=0.002, which is quite sensitive. Results from transmission spectra agree well with those obtained from the band structure theory.Comment: 12 pages including 7 figure

Experimental and Finite-Difference Time-Domain Technique Characterization of Transverse In-Line Photonic Crystal Fiber

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Transverse characterization of high air-fill fraction tapered photonic crystal fiber

We demonstrate tapering of a high air-fill fraction photonic crystal fiber by using the flame-brushing technique. Transverse probing along the taper allows us to ascertain how the microstructure is preserved during tapering. Experimental results are compared with numerical simulations performed with the finite-difference time-domain and plane-wave expansion methods. Through this investigation we find that the fiber geometry is well preserved throughout the tapering process and we resolve the apparent discrepancies between simulation and experiment that arise through the finite extent of the fiber microstructure.8 page(s

Microfluidic tunable photonic band-gap device

We introduce a method for tuning a photonic band-gap material by means of displacing microfluidic plugs. The fluid is introduced into air voids that constitute the structure of the photonic crystal and is displaced using a capillary heater. The photonic crystal geometry is obtained using a microstructured optical fiber, comprising a periodically spaced array of air holes that is interrogated in the transverse direction, creating a 'tall microchip'. Optical spectra are compared to band structure calculations of an idealized band-gap material

Single-mode tellurite glass holey fiber with extremely large mode area for infrared nonlinear applications

We report the fabrication of a large mode area tellurite holey fiber from an extruded perform, with a mode area of 3000µm2. Robust single-mode guidance at 1.55µm was confirmed by both optical measurement and numerical simulation. The propagation loss was measured as 2.9dB/m at 1.55µm. A broad and flat supercontinuum from 0.9 to 2.5µm with 6mW output was obtained with a 9cm length of this fiber

Bioactive “self-sensing” optical systems

Free-standing silk films are useful materials to manufacture nanopatterned optical elements and to immobilize bio-dopants such as enzymes while maintaining their biological activity. These traits were combined by incorporating hemoglobin into free-standing silk diffraction gratings to fabricate chemically responsive optofluidic devices responsive to ambient gas conditions, constituting a simple oxygen sensor. This type of self-analyzing optical system is enabled by the unique ability to reproduce high-fidelity optical structures in silk while maintaining the activity of entrapped proteins such as hemoglobin. These bioactive optical devices offer a direct readout capability, adding utility into the bioresponsive material arena