A bent taper is provided that includes one or more waveguide bends, at least one of which has a tapering waveguide width along at least a portion thereof. In one embodiment, the bent taper is an S-shaped bent taper that is configured as a TE0-TE1 mode convertor. Such a bent taper can be combined with a linear bi-layer taper configured as a TM0-TE1 mode converter to form a TM0-TE0 polarization rotator.

A bent taper is provided that includes one or more waveguide bends, at least one of which has a tapering waveguide width along at least a portion thereof. In one embodiment, the bent taper is an S-shaped bent taper that is configured as a TE0-TE1 mode convertor. Such a bent taper can be combined with a linear bi-layer taper configured as a TM0-TE1 mode converter to form a TM0-TE0 polarization rotator.

Photonic integrated circuits required connection to germanium doped silica cored optical fibers or silica cored and fluorine doped silica cladding optical fibers which have low index contrast and large mode field diameters. However, the optical waveguide within a photonic integrated circuit such as formed using silicon-on-insulator or compound semiconductors tends to be high index contrast and small mode field diameter. Accordingly, it is necessary to implement adiabatic waveguide tapers with a high coupling efficiency and small footprint in order to couple into the photonic integrated circuits to/from the optical fiber. Prior art tapers have been generally high loss and absorb valuable die footprint. In contrast the inventors demonstrate a small low loss waveguide taper designed using a methodology they refer to a “constant loss”.

Photonic integrated circuits required connection to germanium doped silica cored optical fibers or silica cored and fluorine doped silica cladding optical fibers which have low index contrast and large mode field diameters. However, the optical waveguide within a photonic integrated circuit such as formed using silicon-on-insulator or compound semiconductors tends to be high index contrast and small mode field diameter. Accordingly, it is necessary to implement adiabatic waveguide tapers with a high coupling efficiency and small footprint in order to couple into the photonic integrated circuits to/from the optical fiber. Prior art tapers have been generally high loss and absorb valuable die footprint. In contrast the inventors demonstrate a small low loss waveguide taper designed using a methodology they refer to a “constant loss”.

A bricked sub-wavelength periodic waveguide and a modal adapter, power divider and polarization splitter that use the waveguide. The waveguide includes blocks disposed periodically with a period “L.sub.z” on a substrate and which alternate with a covering material. The first blocks have a width “a.sub.x” and the second blocks have a width “b.sub.x”, alternating on the substrate according to a period “L.sub.x”, the second blocks being shifted a distance “d.sub.z” the first blocks in the direction of propagation. A modal adapter, a power divider and a polarization splitter all use the periodic waveguide and can operate with larger wave periods without leaving the sub-wavelength regime.

A three-dimensional photonic integrated structure includes a first semiconductor substrate and a second semiconductor substrate. The first substrate incorporates a first waveguide and the second semiconductor substrate incorporates a second waveguide. An intermediate region located between the two substrates is formed by a one dielectric layer. The second substrate further includes an optical coupler configured for receiving a light signal. The first substrate and dielectric layer form a reflective element located below and opposite the grating coupler in order to reflect at least one part of the light signal.

A three-dimensional photonic integrated structure includes a first semiconductor substrate and a second semiconductor substrate. The first substrate incorporates a first waveguide and the second semiconductor substrate incorporates a second waveguide. An intermediate region located between the two substrates is formed by a one dielectric layer. The second substrate further includes an optical coupler configured for receiving a light signal. The first substrate and dielectric layer form a reflective element located below and opposite the grating coupler in order to reflect at least one part of the light signal.

A photonic integrated circuit (“PIC”) bandpass filter with polarization diversity can comprise a polarization management stage operable to receive a polarization diverse light input and to output an intermediate beam having a uniform polarization, and a filter stage operable to receive the intermediate beam from the polarization management stage, to filter the intermediate beam, and to output a filter output beam. Energy from both an in-plane polarization and an out-of-plane polarization of the polarization diverse light input can thereby be transferred to the filter stage.

A photonic integrated circuit (“PIC”) bandpass filter with polarization diversity can comprise a polarization management stage operable to receive a polarization diverse light input and to output an intermediate beam having a uniform polarization, and a filter stage operable to receive the intermediate beam from the polarization management stage, to filter the intermediate beam, and to output a filter output beam. Energy from both an in-plane polarization and an out-of-plane polarization of the polarization diverse light input can thereby be transferred to the filter stage.

A system for integrated power combiners is disclosed and may include receiving optical signals in input optical waveguides and phase-modulating the signals to configure a phase offset between signals received at a first optical coupler, where the first optical coupler may generate output signals having substantially equal optical powers. Output signals of the first optical coupler may be phase-modulated to configure a phase offset between signals received at a second optical coupler, which may generate an output signal having an optical power of essentially zero and a second output signal having a maximized optical power. Optical signals received by the input optical waveguides may be generated utilizing a polarization-splitting grating coupler to enable polarization-insensitive combining of optical signals. Optical power may be monitored using optical detectors. The monitoring of optical power may be used to determine a desired phase offset between the signals received at the first optical coupler.