Wavelength-Flattened Three Core Optical Coupler Power Splitters in Ion-Exchanged Glass

Abstract

Optical power splitters are vital devices in integrated optics and broadband signal distribution systems. Y-junctions, optical 3dB couplers and fused tapered optical fibre couplers are currently serving as power dividers in integrated optic circuits and networks. Although conventional Y-junctions are advantageous because of their less sensitivity to wavelength, they have a disadvantage of large device length because a small branching angle is necessary to keep the loss reasonably small1,2. On the other hand, the performance of the conventional directional coupler strongly depends on wavelength. This wavelength dependence is not favourable for power splitter or combiner to optical signal processing systems. Therefore, wavelength-flattened couplers are essential components for dividing optical signals while maintaining given splitting ratio without wavelength dependence. Using silica-based three core planar optical coupler, this characteristics could be obtainable3. Many researchers studied the fundamental properties of three core planar optical waveguide coupler both theoretically and experimentally3–9. Among those, Donnelly et.a1.5–7 have done significant work related to the optical power dividers and combiners with three core couplers. Also, Hardy and Streifer8 have done thorough mathematical investigation of three waveguide system using new coupled mode formulation. Depending on various factors, this scheme is promising for optical power dividing applications.