Patent ID: 8699837
Filing Date: 2014-04-15
Classification: G02B

Abstract:
1. A coupler for use in coupling a radiation beam from a planar waveguide circuit into an optical element external to the planar waveguide circuit, the coupler comprising: an input waveguide formed in the planar waveguide circuit for transmitting the radiation beam; a splitter formed in the planar waveguide circuit having a first input port coupled to the input waveguide; and at least two sub-beam output ports, the splitter being configured to split the radiation beam transmitted by the input waveguide into at least two distinct radiation sub-beams, each outputted from the splitter at a different output port; at least two distinct sub-beam waveguides formed in the planar waveguide circuit, each sub-beam waveguide having an input end and an output end, the input end of each sub-beam waveguide being coupled to one of the output ports of the splitter; and at least two distinct sub-gratings formed on the planar waveguide circuit, the output end of each sub-beam waveguide being coupled to a distinct one of the sub-gratings, thereby coupling the respective output port of the splitter to the distinct one of the sub-gratings; wherein each of the distinct sub-gratings is adapted to couple radiation from its respective sub-beam waveguide out of the planar waveguide circuit at a surface thereof, such that all radiation coupled between the input waveguide and the optical element is coupled from the sub-gratings in substantially one direction.