A method is disclosed to provide improved fiber inline optical power monitoring that eliminates the need for micro-bending the fiber or for fabricating micro-reflector on the fiber. A subset of light is tapped through an offset at a fusion-spliced upstream and downstream optic fiber, and is guided out of the downstream fiber by a light guide to a reflector and photo-sensing measurement. The disclosed inline fiber monitoring is thus cost effective, wavelength independence, reliable, stable, and also causes less light transmission loss.

Proposed is a device for switching an optical signal, the device including a first waveguide constituting an input port and a first output port; and a second waveguide constituting a second output port, wherein the first waveguide is formed of a first material, wherein the second waveguide is formed of the first material and contains a second material, wherein a gap between the first and second waveguides has a first value in a first section, a gap therebetween has a value increasing from the first value to a second value in a second section, and a gap therebetween has a third value in a third section, wherein at least one portion of the first section and at least one portion of the second section overlap in the one section, and wherein a grating structure applies to the first and second waveguides in at least one portion of the first section.