Bandwidth engineering of photonic crystal waveguide bends

Abstract

An effective design principle has been applied to photonic crystal waveguide bends fabricated in silicon-on-insulator material using deep UV lithography resulting in a large increase in the low-loss bandwidth of the bends. Furthermore, it is experimentally demonstrated that the absolute bandwidth range can be adjusted in a post-fabrication thermal oxidation process.Introduction: The planar photonic crystal waveguide (PhCW) has numerous potential applications because of its unique capability to control the propagation of light by utilising the photonic bandgap (PBG) effect [1,2]. This effect allows the interaction between light and the PhCW to take place on a minute scale [3,4]. Thereby, the overall size of optical components based on PhCW structures may be greatly minimised and, correspondingly, device packing density increased. Recent advances in deep UV lithography at 248 nm [5] have made mass fabrication of optical ultra-compact PhCW devices viable by employing existing fabrication methods commonly encountered in the semiconductor electronics industry.Research has now reached a level where existing fabrication technologies allow manufacture of PhCW structures with low propagation losses [6][7][8][9]. Hence, there is presently worldwide focus on the design and fabrication of PhCW structures possessing adequate bandwidths. PhCW structures with 20-40 nm useful optical bandwidths have previously been demonstrated [3,10,11]. Recently, Borel et al. [12] have demonstrated that a new inverse design method, topology optimisation, can be utilised to dramatically increase the bandwidth of a PhCW component. However, some of the holes in these components have special sizes and shapes that currently cannot be manufactured using deep UV lithography and, thus, cannot currently be mass fabricated. Except for these topology-optimised structures, no bandgap-based PhCW components have been demonstrated with satisfactory performance in a broad wavelength range.In this Letter, we present an alternative design strategy, which also leads to large bandwidths of PhCW bends, and that is suitable for fabrication utilising deep UV lithography. Furthermore, we demonstrate a simple experimental procedure employing thermal oxidation on how to tune the absolute position of the operational bandwidth for an already fabricated batch of samples.

MRTD Analysis of PhC Devices

“…The structure, whose schematic diagram is given in Figure 9.11, consists of a single microcavity coupled to a straight waveguide based on a PBG structure [5][6][7][8][9][10][11][12][13][14][15]. The periodic square array consists of dielectric rods with refractive index, n rods = 3.4 in air, a lattice constan,t a = 0.58 µm, and rod radius, r rods = 0.18a.…”

PC-SMZ-Based All-Optical Flip-Flop Switch : PC-FF

“…This is because the total waveguide configurationbecomes more omplicatedwithanI.,inreasefdi 'nme f b s irectional couples and intersections, while a conventional design method has a limitation in improving this problem. Here, a new design method named topology optimization (TO) [6] is shown in response to this demand. On the other hand, the The TO method has been developed for design of the PC structures very recently [6].…”

“…Here, a new design method named topology optimization (TO) [6] is shown in response to this demand. On the other hand, the The TO method has been developed for design of the PC structures very recently [6]. The optimized patterning is not restricted to the uniform hole pattern but allows a deformed one.…”

Design and Modeling of the Photonic Crystal Waveguide Structure for Heat‐Assisted Magnetic Recording

“…e PC's excellent transmission properties [14][15][16] and physical flexibility are attractive to minuscule WG fabrication. It can be bent to fit in a limited space and still achieve desirable performance [14,15,[17][18][19]. A significant enhancement in operating bandwidth [18,19] has also been reported.…”