David Torres, Ori Weisberg, Gil Shapira, Charalambos Anastassiou, Burak Temelkuran, Max Shurgalin, Steven Jacobs, Rokan Ahmad, Tairan Wang, Uri Kolodny, Stanley Shapshay, Zimmern Wang, Anand Devaiah, Urmen Upadhyay, Jamie Koufman
The CO2 laser is the most widely used laser in laryngology, offering very precise cutting, predictable depth of penetration, and minimal collateral damage due to the efficient absorption of CO2 laser by water. Surgical applications of CO2 laser in microlaryngoscopy include removal of benign lesions and early-stage laryngeal cancer. A Transoral Laser Microsurgery (TLM) approach is routinely employed for treatment of laryngeal cancer; however, the role of TLM in advanced malignant lesions remains controversial. The main limiting factor of TLM is the restrictive exposure of the endoscopes combined with the limited cutting ability offered by the existing micromanipulator, enabling cutting only along the straight line-of-sight axis. A flexible fiber delivery system offering a very high quality output beam can offer tangential cutting and can therefore significantly enhance the existing surgical capabilities. Moreover, a flexible fiber for CO2 laser delivery can be used for treatment of benign conditions through flexible endoscopy in an office setting using local anesthesia. OmniGuide Communications Inc. (OGCI) has fabricated a photonic bandgap fiber capable of flexibly guiding CO2 laser energy. Results of laryngeal in-vivo and in-vitro animal studies will be presented. We will discuss the system setup, fiber performance and clinical outcomes. In addition we will present the results of the first human treatment and highlight additional otolaryngology conditions, which will likely benefit from the new technology herein presented.
Laser cutting of human bone and tissue is one of the oldest and most widespread applications of biophotonics. Due to the unique absorption of different kinds of tissue, choosing an appropriate laser wavelength allows selective ablation of tissue. Consequently, a large variety of laser sources with different emission wavelengths have been successfully applied to an equally large variety of medical indications. However, only a limited set of successful tissue-interaction experiments have translated into standard minimally-invasive procedures. One of the main reasons for this discrepancy between medical research and clinical practice is the lack of a commercially viable, flexible, and easy-to-use fiber optic beam delivery systems for wavelengths longer than 2 μm. In this paper, we will show how OmniGuide fibers, a new type of photonic bandgap fibers, could solve this problem. Recent performance data will be presented for both straight and bent fibers, including losses and power capacity, for delivery of CO2 lasers. We will also highlight medical procedures where these fibers could find first applications.
We argue that OmniGuide fibers, which guide light within a hollow core by concentric multilayer films having the property of omnidirectional reflection, have the potential to lift several physical limitations of silica fibers. We show how the strong confinement in OmniGuide fibers greatly suppresses the properties of the cladding materials: even if highly lossy and nonlinear materials are employed, both the intrinsic losses and nonlinearities of silica fibers can be surpassed by orders of magnitude. This feat, impossible to duplicate in an index-guided fiber with existing materials, would open up new regimes for long-distance propagation and dense wavelength-division multiplexing (DWDM). The OmniGuide-fiber modes bear a strong analogy to those of hollow metallic waveguides; from this analogy, we are able to derive several general scaling laws with core radius. Moreover, there is strong loss discrimination between guided modes, depending upon their degree of confinement in the hollow core: this allows large, ostensibly multi-mode cores to be used, with the lowest-loss TE01 mode propagating in an effectively single-mode fashion. Finally, because this TE01 mode is a cylindrically symmetrical ('azimuthally' polarized) singlet state, it is immune to polarization-mode dispersion (PMD), unlike the doubly-degenerate linearly-polarized modes in silica fibers that are vulnerable to birefringence.
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