Hollow Photonic Bandgap Fiber Research Articles

Laser guiding of cold molecules in a hollow photonic bandgap fiber

We propose a promising scheme to guide buffer-gas cooled arbitrary neutral molecules in a hollow-core photonic bandgap (HC-PBG) fiber by using a red-detuned Gaussian mode and calculate the optical coupling efficiency of the Gaussian mode in the HC-PBG and its optical potential for I2 molecules. Also, we calculate both the straight guiding efficiency and bend guiding one by using a classical model and the dynamic process of the laser guiding of cold molecules in the HC-PBG by Monte Carlo simulation, by which we obtain the transverse and longitudinal velocity distributions of the output guided molecular beam. Our study shows that when the input laser power is 2 kW, the straight guiding efficiency is ~24.6% and when the input laser power is 200 W and R=0.2 cm, the bent guiding efficiency is ~1.2%. We also find from the simulated results that our laser bent guiding scheme is a simple and desirable method to generate a CW cold arbitrary molecular beam.

Carbon Dioxide Laser Fiber for Laryngeal Cancer Surgery

The carbon dioxide laser has evolved to be the premier dissecting instrument for hemostatic cutting during endolaryngeal cancer resection. However, dissection is limited to mirror-reflected line-of-sight delivery of the laser. A recently developed flexible, hollow photonic bandgap fiber (PBF) appears to offer advantages in endolaryngeal dissection. The suitability of the PBF for human application was evaluated in a canine experiment in which human surgical procedures for microlaryngoscopic en bloc partial laryngectomy were simulated. The specimens that were resected endoscopically and the completion laryngectomy specimen were evaluated histologically. Observations from this experiment revealed that en bloc partial laryngectomy procedures were substantially easier to achieve as compared with prior experience in humans. This improvement resulted from three factors: 1) enhanced tangential dissection due to increased angulation of the laser energy, 2) enhanced procedural orientation due to proprioception of the tissues in contact mode, and 3) improved hemostasis. Histopathologic analysis of the resection margins revealed minimal thermal trauma. The PBF shows substantial promise for human application in endoscopic partial laryngectomy. It will likely enhance the ability of any surgeon to extend his or her indications for performing endoscopic laryngeal cancer resections regardless of philosophy (en bloc resection or piecemeal).

Colloidal photonic crystal cladded optical fibers: Towards a new type of photonic band gap fiber

A facile approach of fabricating a new type of hollow photonic band gap fibers is proposed. Templates for generating such fibers are demonstrated by a complete and uniform coating of a standard silica optical fiber (125 mum diameter) with a three-dimensional colloidal photonic crystal through isothermal heating evaporation induced self-assembly. The photonic crystal cylindrical annulus is characterized by optical and scanning electron microscopy, and is found to yield a 1.4-mum stop band by optical reflection and transmission spectroscopy. The results also demonstrate a practical means of enveloping macro- or micro-curved surfaces with three-dimensional photonic crystals, a task that is geometrically challenging by other photonic crystal fabrication methods.

Advances in Efficiency, Speed Reported at OFC 2004

Researchers unveiled impressive results in component design and system performance at OFC 2004. Highlights included record low loss in a hollow photonic bandgap fiber and all-optical packet switching at a staggering rate of 160 Gbit/s.

Wavelength-scalable hollow optical fibres with large photonic bandgaps for CO2 laser transmission.

Conventional solid-core optical fibres require highly transparent materials. Such materials have been difficult to identify owing to the fundamental limitations associated with the propagation of light through solids, such as absorption, scattering and nonlinear effects. Hollow optical fibres offer the potential to minimize the dependence of light transmission on fibre material transparency. Here we report on the design and drawing of a hollow optical fibre lined with an interior omnidirectional dielectric mirror. Confinement of light in the hollow core is provided by the large photonic bandgaps established by the multiple alternating submicrometre-thick layers of a high-refractive-index glass and a low-refractive-index polymer. The fundamental and high-order transmission windows are determined by the layer dimensions and can be scaled from 0.75 to 10.6 micro m in wavelength. Tens of metres of hollow photonic bandgap fibres for transmission of carbon dioxide laser light at 10.6 micro m wavelength were drawn. The transmission losses are found to be less than 1.0 dB m(-1), orders of magnitude lower than those of the intrinsic fibre material, thus demonstrating that low attenuation can be achieved through structural design rather than high-transparency material selection.