The invention relates to a photonic interposer (300) for coupling light between a first optical fiber (200I) and a photonic integrated circuit (100) and between the photonic integrated circuit (100) and a second optical fiber (200O), the photonic interposer (300) comprising a polarization selective beam splitter-/combiner (310) adapted to split an input light beam (400CI) with first and second polarizations, from the first optical fiber (200I), into a first light beam (400AI) and a second light beam (400BI) and to redirect one of the first and second light beams (400AI, 400BI), and the first light beam (400AI) has the first polarization and the second light beam (400BI) has the second polarization which is different from the first polarization; and the polarization selective beam splitter-/combiner (310) is adapted to combine modulated first and second light beams (400AO, 400BO) from the photonic integrated circuit (100) into a combined light beam (400CO) to be coupled to the second optical fiber (220O), and the modulated first and second light beams (400AO, 400BO) are respectively subject to the first and second light beams (400AI, 400BI) being modulated by a same data stream, by the photonic integrated circuit (100).

An optical coupling device can include a first birefringent layer having opposing first and second surfaces. The first birefringent layer can split incident light received at the first surface into first and second beams. The first and second beams can have respective polarization orientations that are orthogonal to each other. The first birefringent layer can propagate the first and second beams along respective first and second paths within the first birefringent layer to the second surface. The first and second beams can be spatially separated at the second surface. A redirection layer facing the second surface of the first birefringent layer can include first and second grating couplers configured to respectively redirect the first and second beams to propagate within the redirection layer as respective third and fourth beams. In some examples, the third and fourth beams can have respective polarization orientations that are parallel to each other.

An optical device that can be used as an optical hybrid, e.g., in CMOS-compatible PICs. In an example embodiment, the optical device has a single optical input and four optical outputs. The two optical input signals to be mixed in the optical device are applied to the single optical input as transverse electric (TE) and transverse magnetic (TM) polarization components, respectively, of the corresponding polarization-multiplexed optical input signal. In response to the latter, the optical device causes the four outputs to receive four different relative-phase combinations of the two optical input signals, each combination being coupled into a TE waveguide mode at the respective optical output. A PIC having one or more instances of the optical device can be used, e.g., to implement a coherent optical receiver, wherein the TE and TM polarization components of the optical input signal are populated by a communication signal and a local-oscillator signal.

A wavelength-division multiplexed (WDM) polarization-independent transmissive modulator (PITM) that receives a multi-wavelength continuous wave (CW) light of indeterminate polarization, splits the multi-wavelength CW light into two transverse electric (TE) polarized components, demultiplexer the polarized components into single-wavelength CW lights, modulates the single-wavelength CW lights using four-port cross-state or bypass-state modulators, multiplexes the modulated output of the four-port modulators (FPM) into two polarized modulated components, and combines the two polarized modulated components into a multi-wavelength modulated output signal.

An apparatus of polarization self-compensated delay line interferometer. The apparatus includes a first waveguide arm of a first material of a first length disposed between an input coupler and an output coupler and a second waveguide arm of the first material of a second length different from the first length disposed between the same input coupler and the same output coupler. The apparatus produces an interference spectrum with multiple periodic passband peaks where certain TE (transverse electric) and TM (transverse magnetic) polarization mode passpand peaks are lined up. The apparatus further includes a section of waveguide of a birefringence material of a third length added to the second waveguide arm to induce a phase shift of the lined-up TE/TM passband peaks to a designated grid as corresponding polarization compensated channels of a wide optical band.

A multi-stage interferometer circuit of the present invention includes: a multiplexing port; (N1) stages of lattice type two-beam interferometers, wherein each stage includes a two-beam delay circuit having a path length difference of an integral multiple of M.Math. L/2, and wherein the two-beam delay circuit of the lattice type two-beam interferometer of the first stage is connected to the multiplexing port; an M-beam interferometer including: two sets of 1(M/2) optical couplers connected to the first optical coupler of the lattice type two-beam interferometer at the final stage; an M-array delay circuit, each delay circuit of which has a delay length different from each other by L; and MM optical couplers; and M demultiplexing ports, wherein one or more transversal filters are arranged inside the multi-stage interferometer circuit so that the light guided between the demultiplexing port and the multiplexing ports passes therethrough at least once.

An apparatus of polarization self-compensated delay line interferometer. The apparatus includes a first waveguide arm of a first material of a first length disposed between an input coupler and an output coupler and a second waveguide arm of the first material of a second length different from the first length disposed between the same input coupler and the same output coupler. The apparatus produces an interference spectrum with multiple periodic passband peaks where certain TE (transverse electric) and TM (transverse magnetic) polarization mode passband peaks are lined up. The apparatus further includes a section of waveguide of a birefringence material of a third length added to the second waveguide arm to induce a phase shift of the lined-up TE/TM passband peaks to a designated grid as corresponding polarization compensated channels of a wide optical band.

An integrated optical device is mounted with two optical fibers that transmit a light and, as functional components in a space of a housing forming an optical path from one of the optical fibers to the other light, is provided with an optical power attenuator that attenuates, using vignetting, a light incident from the one optical fiber or a light emitted from the other optical fiber and a tunable filter that selects a light of a predetermined wavelength from among the light incident from the one optical fiber and emits this selected light from the other optical fiber.

An apparatus comprising a polarization beam splitter optically coupled to a first light path and a second light path and configured to receive a CW light having a plurality of wavelengths, forward a first light beam of the CW light along the first light path, and forward a second light beam of the CW light along the second light path. A first multiplexer coupled to the first light path and configured to de-multiplex the first light beam into a first plurality of channels each corresponding to one of the plurality of wavelengths. A second multiplexer coupled to the second light path and configured to de-multiplex the second light beam into a second plurality of channels each corresponding to one of the plurality of wavelengths. A modulator coupled to the first multiplexer and the second multiplexer and configured to modulate the first plurality of channels and the second plurality of channels.

An integrated polarization splitter and rotator (PSR) employs the TE0 and TE1 modes of propagating light, rather than the TE0 and TM0 modes used in conventional prior art PSR. The integrated PSR exhibits appreciably flatter wavelength response because it does not require a directional coupler to de-multiplex incoming polarizations. The PSR allows tuning of the TM0 loss to reduce polarization dependent loss (PDL). This integrated polarization splitter and rotator is applicable to all integrated platforms including Silicon-on-Insulator (SOI) and III-V semiconductor compound systems. The PSR may be very compact (122 m.sup.2), and provides low loss (<0.3 dB across the C-band) and ultra-broadband operation. The PSR also affords better control of polarization dependent losses.