A planar lightwave circuit has a waveguide having a bend and plurality of multiple trenches with parallel front and back interfaces. The trench and waveguide refractive indexes are different such that a refractive interface is defined between the waveguide and the trench. The trench may include a material of higher refractive index than the waveguide, such as silicon, or alternatively a material having a lower refractive index than the waveguide, such as an air void. The trench is disposed on the waveguide bend such that the front and back planar interfaces have an angle of incidence to a direction of the lightwave propagation from the waveguide. The invention also includes beamsplitters that include trenches that reflect a portion of a lightwave in a first direction and a portion of a lightwave in a second direction.