Steven A. Jacobs
Tektronix
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Featured researches published by Steven A. Jacobs.
Optics Express | 2001
Steven G. Johnson; Mihai Ibanescu; Maksim Skorobogatiy; Ori Weisberg; Torkel Engeness; Marin Soljacic; Steven A. Jacobs; John D. Joannopoulos; Yoel Fink
We present the light-propagation characteristics of OmniGuide fibers, which guide light by concentric multi-layer dielectric mirrors having the property of omnidirectional reflection. We show how the lowest-loss TE_01 mode can propagate in a single-mode fashion through even large-core fibers, with other modes eliminated asymptotically by their higher losses and poor coupling, analogous to hollow metallic microwave waveguides. Dispersion, radiation leakage, material absorption, nonlinearities, bending, acircularity, and interface roughness are considered with the help of leaky modes and perturbation theory, and both numerical results and general scaling relations are presented. We show that cladding properties such as absorption and nonlinearity are suppressed by many orders of magnitude due to the strong confinement in a hollow core, and other imperfections are tolerable, promising that the properties of silica fibers may be surpassed even when nominally poor materials are employed.
Optics Express | 2002
Maksim Skorobogatiy; Steven A. Jacobs; Steven G. Johnson; Yoel Fink
Perturbation theory formulation of Maxwells equations gives a theoretically elegant and computationally efficient way of describing small imperfections and weak interactions in electro-magnetic systems. It is generally appreciated that due to the discontinuous field boundary conditions in the systems employing high dielectric contrast profiles standard perturbation formulations fail when applied to the problem of shifted material boundaries. In this paper we developed a novel coupled mode and perturbation theory formulations for treating generic non-uniform (varying along the direction of propagation) perturbations of a waveguide cross-section based on Hamiltonian formulation of Maxwell equations in curvilinear coordinates. We show that our formulation is accurate and rapidly converges to an exact result when used in a coupled mode theory framework even for the high index-contrast discontinuous dielectric profiles. Among others, our formulation allows for an efficient numerical evaluation of induced PMD due to a generic distortion of a waveguide profile, analysis of mode filters, mode converters and other optical elements such as strong Bragg gratings, tapers, bends etc., and arbitrary combinations of thereof. To our knowledge, this is the first time perturbation and coupled mode theories are developed to deal with arbitrary non-uniform profile variations in high index-contrast waveguides.
Biomedical optics | 2004
Charalambos Anastassiou; Ori Weisberg; Gregor Frank Dellemann; Max Shurgalin; Steven A. Jacobs; William A. Farinelli; James Goell; Uri Kolodny
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.
Optics Express | 2003
Maksim Skorobogatiy; Charalambos Anastassiou; Steven G. Johnson; Ori Weisberg; Torkel Engeness; Steven A. Jacobs; Rokan Ahmad; Yoel Fink
We present a rigorous analysis methodology of fundamental to higher order mode converters in step index few mode optical fibers. We demonstrate experimental conversion from a fundamental LP01 mode to the higher order LP11 mode utilizing a multiple mechanical bend mode converter. We perform a quantitative analysis of the measured light intensity, and demonstrate a modal decomposition algorithm to characterize the modal content excited in the fiber. Theoretical modelling of the current mode converter is then performed and compared with experimental findings.
Journal of The Optical Society of America B-optical Physics | 2002
Maksim Skorobogatiy; Mihai Ibanescu; Steven G. Johnson; Ori Weisberg; Torkel Engeness; Steven A. Jacobs; Yoel Fink
We develop a novel perturbation theory formulation to evaluate polarization-mode dispersion (PMD) for a general class of scaling perturbations of a waveguide profile based on generalized Hermitian Hamiltonian formulation of Maxwell’s equations. Such perturbations include elipticity and uniform scaling of a fiber cross section, as well as changes in the horizontal or vertical sizes of a planar waveguide. Our theory is valid even for discontinuous high-index contrast variations of the refractive index across a waveguide cross section. We establish that, if at some frequencies a particular mode behaves like pure TE or TM polarized mode (polarization is judged by the relative amounts of the electric and magnetic longitudinal energies in the waveguide cross section), then at such frequencies for fibers under elliptical deformation its PMD as defined by an intermode dispersion parameter t becomes proportional to group-velocity dispersion D such that t 5 lduDu, where d is a measure of the fiber elipticity and l is a wavelength of operation. As an example, we investigate a relation between PMD and group-velocity dispersion of a multiple-core step-index fiber as a function of the core‐clad index contrast. We establish that in this case the positions of the maximum PMD and maximum absolute value of group-velocity dispersion are strongly correlated, with the ratio of PMD to group-velocity dispersion being proportional to the core‐clad dielectric contrast.
Biomedical optics | 2005
David Torres; Ori Weisberg; Gil Shapira; Charalambos Anastassiou; Burak Temelkuran; Max Shurgalin; Steven A. Jacobs; Rokan Ahmad; Tairan Wang; Uri Kolodny; Stanley M. Shapshay; Zimmern Wang; Anand K. Devaiah; Urmen D. Upadhyay; Jamie A. 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.
Journal of Lightwave Technology | 2005
Maksim Skorobogatiy; Steven A. Jacobs; Steven G. Johnson; Charalambos Anastassiou; Burak Temelkuran
We investigate heating from field propagation, coupling, and bending, which are the potential failure mechanisms for an emerging new type of high-power radiation guides-hollow photonic Bragg fibers. Continuous wave (CW) and pulsed radiation sources are considered, assuming continuous operation of the laser source.
Specialty Optical Fibers Handbook | 2007
Steven A. Jacobs; Burak Temelkuran; Ori Weisberg; Mihai Ibanescu; Steven G. Johnson; Marin Soljacic
This chapter discusses the properties, applications, and manufacture of hollow-core fibers. Hollow-core fibers guide light by means of a reflective cladding. Because the index of refraction of the hollow core is smaller than that of the cladding materials, the guiding mechanism cannot be based on total internal reflection, as is the case for traditional optical fibers. Instead, three major types of reflective cladding are used—a metal tube with optional dielectric coating, a multilayer dielectric Bragg mirror, or a two-dimensional photonic crystal. The simplest method for guiding light in a hollow core is by enclosing the core with a highly reflective metal. The metal acts as a mirror, so that fields from the core incident on the metal are reflected back into the core, providing the confinement mechanism. When the interior of the waveguide consists of a single homogeneous dielectric material, the mode fields can be separated into two polarizations—transverse electric and transverse magnetic with vanishing axial components of the electric and magnetic fields, respectively.
Optics Express | 2016
Steven A. Jacobs; Robert A. Marsland
We present a new method, blind EVM minimization, for constellation recovery and transmitter impairment evaluation of dual polarization optical signals with complex modulation formats. Using simulated data, for which transmitter impairments are known exactly, the method is shown to be accurate and robust. In addition, the method is successfully tested on measured QPSK and QAM16 data. Because of its relatively long run-time, the method might best be used for defining and measuring transmitter impairments and for judging the performance of faster constellation recovery methods that rely on serial parameter evaluation rather than optimization.
Photonic Crystal Materials and Nanostructures | 2004
Maksim Skorobogatiy; Steven A. Jacobs; Steven G. Johnson; Michel Meunier; Yoel Fink
Standard perturbation theory (PT) and coupled mode theory (CMT) formulations fail or exhibit very slow convergence when applied to the analysis of geometrical variations in high index-contrast optical components such as Bragg fibers and photonic crystals waveguides. By formulating Maxwells equations in perturbation matched curvilinear coordinates, we have derived several rigorous PT and CMT expansions that are applicable in the case of generic non-uniform dielectric profile perturbations in high index-contrast waveguides. In strong fiber tapers and fiber Bragg gratings we demonstrate that our formulation is accurate and rapidly converges to an exact result when used in a CMT framework even in the high index-contrast regime. We then apply our method to investigate the impact of hollow Bragg fiber ellipticity on its Polarization Mode Dispersion (PMD) characteristics for telecom applications. Correct PT expansions allowed us to design an efficient optimization code which we successfully applied to the design of dispersion compensating hollow Bragg fiber with optimized low PMD and very large dispersion parameter. We have also successfully extended this methodology to treat radiation scattering due to common geometric variations in generic photonic crystals. As an example, scattering analysis in strong 2D photonic crystal tapers is demonstrated.