A "poor man's approach" to modelling of micro-structured optical fibres

Based on the scalar Helmholtz equation and the finite-difference approximation, we formulate a matrix eigenvalue problem for the calculation of propagation constants, beta(omega), in micro-structured optical fibres. The method is applied to index-guiding fibres as well as air-core photonic bandgap fibres, and in both cases qualitatively correct results are found. The strength of this approach lies in its very simple numerical implementation and its ability to find eigenmodes at a specific eigenvalue, which is of great interest, when modelling defect modes in photonic bandgap fibres.Comment: 9 pages including 5 figures. Accepted for Journal of Optics A: Pure and Applied Optic

Semi-analytical approach to short-wavelength dispersion and modal properties of photonic crystal fibers

We consider photonic crystal fibers made from arbitrary base materials and derive a unified semi-analytical approach for the dispersion and modal properties which applies to the short-wavelength regime. In particular we calculate the dispersion and the effective index and comparing to fully-vectorial plane wave simulations we find excellent agreement. We also calculate asymptotic results for the mode-field diameter and the V-parameter and from the latter we predict that the fibers are endlessly single mode for a normalized air-hole diameter smaller than 0.42, independently of the base material.Comment: 3 pages including 3 figures. Accepted for Opt. Let

Photonic crystal fibres: mapping Maxwell's equations onto a Schrodinger equation eigenvalue problem

We consider photonic crystal fibres (PCFs) made from arbitrary base materials and introduce a short-wavelength approximation which allows for a mapping of the Maxwell's equations onto a dimensionless eigenvalue equations which has the form of the Schrodinger equation in quantum mechanics. The mapping allows for an entire analytical solution of the dispersion problem which is in qualitative agreement with plane-wave simulations of the Maxwell's equations for large-mode area PCFs. We offer a new angle on the foundation of the endlessly single-mode property and show that PCFs are endlessly single mode for a normalized air-hole diameter smaller than ~0.42, independently of the base material. Finally, we show how the group-velocity dispersion relates simply to the geometry of the photonic crystal cladding.Comment: 16 pages including 6 figure

Metabolic engineering of Saccharomyces cerevisiae to harness natures valuable compounds

Nature contains a treasure trove of small molecule ingredients that can improve health, wellness and nutrition. However, most of these ingredients have “issues”: the organism that makes the compound of interest is too rare, too hard to grow or does not make enough of it. Hence, the ingredient is not available at the right quality, the right price nor the necessary amount. These issues need to be solved in order to allow a larger society having access to these valuable ingredients in a sustainable manner at low costs. Evolva is leader in metabolic engineering of yeast for the production by fermentation of a diverse array of small molecule ingredients. The small molecule ingredients introduced to the market by Evolva include Resveratrol, Nootkatone, Valencene and Vanillin. Evolva and its commercial partner will launch the next-generation stevia sweetener EverSweetTM in 2018. All of these molecules are produced in a sustainable, reliable, cost-effective production at consistent quality by fermentation of engineered yeast strains, using abundant, inexpensive raw materials. Of particular interest to Evolva are the terpenes, which are known to work in a wide range of high value applications including sweeteners, flavors and fragrances, personal care, as well as human and animal health products. In spite of proven efficacy, there has been relatively little commercial development of terpene-based ingredients, mostly due to their high production cost. Here, we will present a number of terpene-based Evolva ingredient projects such as e.g. the stevia pathway, which use Evolva’s technology platforms, allowing us to produce these ingredients in an efficient and sustainable way. Please click Additional Files below to see the full abstract

Mode degeneration in bent photonic crystal fiber study by using the finite element method

The development of highly dispersive lower and higher order cladding modes and their degeneration with respect to the fundamental core mode in a bent photonic crystal fiber is rigorously studied by use of the full-vectorial finite element method. It is shown that changes in the bending radius can modify the modal properties of large-area photonic crystal fibers, important for a number of potential practical applications