We describe methods and devices for manipulating optical signals. A method of manipulating an optical signal comprises providing a device (100) comprising a layer (106) of blue phase liquid crystal in the path of the optical signal; and applying a dynamically varying spatial pattern of voltages across the layer (106) of blue phase liquid crystal, thereby causing the refractive index of the layer (106) of blue phase liquid crystal to vary according the dynamically varying spatial pattern.

A wavelength selective switch includes a first optical switching engine. The optical switching engine is configured to deflect a transmission direction of a first light sub-beam along a port direction to send a deflected first light sub-beam to a first reflector, and to deflect a transmission direction of a second light sub-beam along the port direction to send a deflected second light sub-beam to a second reflector. The first reflector reflects the deflected first light sub-beam along a dispersion direction to send a reflected first light sub-beam to a first area of a second optical switching engine. The second reflector reflects the deflected second light sub-beam along the dispersion direction to send a reflected second light sub-beam to a second area of the second optical switching engine.

Embodiments herein describe using an actuator to tune a waveguide. In one embodiment, the tunable waveguide includes a gap between the waveguide and cladding. The actuator can compress the cladding to shrink this air, bringing the cladding closer to the waveguide. Doing so changes the effective refractive index of the waveguide. Alternatively or additionally, the actuator can increase the gap.

An optical switch module includes a housing, at least two first collimators, at least two second collimators, a relay, and plural prisms. The housing has an accommodating space, a first sidewall, and a second sidewall. The first collimators are located on the first sidewall. Each of the first collimators connects even number of first fibers. The second collimators are located on the second sidewall. Each of the second collimators connects even number of second fibers. The second collimators are respectively aligned with the first collimators. The relay is located in the accommodating space and has a rotation support. The prisms are located on the rotation support and respectively between the first and second collimators. The rotation support is configured to enable at least one of the prisms to be in light transmission paths between the first fibers and the second fibers.