A wafer structure includes a diffractive lens disposed on a backside of a wafer and coupled to a front side waveguide, the diffractive lens being configured to receive light and focus the light to the front side waveguide.

A wafer structure includes a diffractive lens disposed on a backside of a wafer and coupled to a front side waveguide, the diffractive lens being configured to receive light and focus the light to the front side waveguide.

In an optical path control device, a light input section 1 forms optical apertures 61a, 61b to output dispersed beams L2a, L2b, respectively, so that propagation angles of the dispersed beams L2a, L2b in an YZ plane are different from each other, at a focal position on the dispersive element 5 side of an optical power element 6. The dispersed beams L2a, L2b propagating at their respective angles different from each other in the YZ plane are individually coupled to optical deflectors 7a, 7b, respectively.

An optical switch and a wavelength division multiplexing optical system are disclosed. In an embodiment an optical switch includes an input port array, an input collimator array, an input micromirror array, an output micromirror array, an output collimator array, and an output port array. All input micromirrors included in the input micromirror array can be deflected in two mutually perpendicular directions. The maximum movable ranges of reflected light that is output after all the input micromirrors reflect incident light with the same incident angle have no common intersection on a plane on which the output micromirror array is located or have a common intersection, and an area of the intersection is less than an area of a reflection region of the output micromirror array.

A wafer structure includes a diffractive lens disposed on a backside of a wafer and coupled to a front side waveguide, the diffractive lens being configured to receive light and focus the light to the front side waveguide.

An optical device may include a set of signal inputs, a set of pilot path inputs, a set of signal outputs, and a set of pilot path outputs. A pilot path output may be coupled to a pilot path input to form a pilot path. The optical device may include a set of elements on the pilot path and on a set of signal paths formed among the set of signal inputs and the set of signal outputs. The optical device may include a photodiode to convert a pilot signal on the pilot path output to an electrical signal, and a controller to selectively adjust one or more elements based at least in part on the electrical signal to compensate for a difference in a current state associated with the set of elements relative to an original state associated with the set of elements.