Paper
2 May 2014 Design and analysis of beam splitters and GRIN lenses using 2D photonic crystals in silicon for telecommunications
Uday B. M., Prita Nair
Author Affiliations +
Abstract
Fiber to planar waveguide interconnects and planar beam modifiers are crucial for the implementing efficient silicon photonic devices for communication applications. In this work, broadband performance in the 1300nm- 1600nm region is ensured by appropriately controlling the spatial variation of the effective index of silicon to realize a beam splitter (1×2) and a quarter wave GRIN lens. Sub wavelength (λ/10) 1D periodic array of low-index air holes in the high index host silicon, along the propagation direction of the optical beam, is repeated, with decreasing or increasing periodicities in the transverse direction to form a 2D photonic crystal(PhC) structure to realize a beam splitter or GRIN lens respectively. The lowest wavelength of 1300nm is used as the design wavelength to ensure less than λ/10 periodicities for all useful wavelength ranges. A decreasing transverse periodicity of 1D hole arrays from the horizontal axis at the centre along the direction of propagation results in formation of 2 high index wave guiding structures towards the edges of the crystal separated by low effective index central region thus leading to formation of a beam splitter. On the other hand increasing transverse periodicity of the defect array leads to lowering of effective index gradually to the edges of the device resulting in the formation of a GRIN lens. FEM analysis of the propagation of electromagnetic field through these structures show that GRIN lens focuses the input beam to a mode field diameter (MFD) of 1.5μm and that MFD of each output arm of the 1×2 splitter is 1.75μm. The decrease in intensities at the focal point of the GRIN lens with increasing input wavelength in the 1300-1600nm is found to be within 6% and that in the two arms of the beam splitter is found to be less than 13%.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Uday B. M. and Prita Nair "Design and analysis of beam splitters and GRIN lenses using 2D photonic crystals in silicon for telecommunications", Proc. SPIE 9130, Micro-Optics 2014, 913015 (2 May 2014); https://doi.org/10.1117/12.2055300
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KEYWORDS
GRIN lenses

Beam splitters

Silicon

Finite element methods

Photonic crystals

Electromagnetic coupling

Radio propagation

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