According to various aspects of the present disclosure, an apparatus is provided. In an aspect, the apparatus includes an optical transceiver having a first port, a second port and an optical switch coupled to the first port and the second port. The optical switch is switchable between a unidirectional port operation mode and a bidirectional port operation mode. When the optical switch is in the unidirectional port operation mode, the first port is configured to send a first optical signal, and the second port configured to receive a second optical signal. When the optical switch is in the bidirectional port operation mode, the first port configured to send the first optical signal and receive the second optical signal, and the second port configured to receive a third optical signal and not send the first signal. Furthermore, a second bidirectional port operation mode is supported with the second port configured to send the first optical signal and receive the second optical signal, and the first port configured to receive a third optical signal and not send the first signal.

A photonic chip is disclosed that comprises a cladding material and an edge coupler. The edge coupler comprises a composite guiding structure that comprises a plurality of substantially parallel planar layers of optical guiding material. Each layer of the composite guiding structure extends into the cladding material, wherein each layer is aligned at a first edge of the photonic chip. The layers overlap along a first axis which is perpendicular to a plane of the planar layers of optical guiding material. The photonic chip is arranged for deposition of a waveguide on the cladding material, the waveguide being arranged to at least partially overlap along the first axis with a layer of the composite guiding structure.

Also disclosed is a method of manufacturing a photonic chip.

An expanded Bell state generator can generate a Bell state on four output modes of a set of m output modes, where m is greater than four. Some expanded Bell state generators can receive inputs on any four of a set of 2m input modes. Subsets of the m output modes can be multiplexed to reduce the number of modes to four. According to some embodiments, a set of 2×2 muxes can be used to rearrange the output modes prior to reducing the number of modes.

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.

Tapered waveguides made of high-index material attached to a tapered optical fiber are provided, enabling access to the optical modes of large, high-index resonators. In some embodiments, an optical fiber having a central axis, a tapered portion, and an untapered portion is provided. The tapered portion is configured to expose an evanescent field. An elongated waveguide is optically coupled to the optical fiber along the tapered portion and parallel to the central axis of the optical fiber. The elongated waveguide has a substantially triangular cross section perpendicular to the central axis of the optical fiber.

The invention relates to a device for coupling a flared laser source (10) and an output waveguide (3), comprising a coupler (20), a combiner (40), and a network of intermediate waveguides (30) located between the coupler and the combiner and comprising a correcting central section (S.sub.c) in which an effective index associated with the guided modes is adjusted so that the optical paths of the intermediate waveguides (30) between the coupler (20) and the combiner (40) are identical to one another.

An optical waveguide adapter assembly comprises a solid core optical waveguide extending between a free end and a coupled end and having a solid waveguiding core with an associated first optical mode field size; a hollow core optical waveguide extending between a free end and a coupled end and having a hollow waveguiding core with an associated second optical mode field size; and an optical mode field adapter extending between a first end and a second end and having a waveguiding core configured to change an optical mode field of a waveguided optical signal substantially between the first optical mode field size at the first end of the optical mode field adapter and the second optical mode field size at the second end of the optical mode field adapter, the first end of the optical mode field adapter joined to the coupled end of the solid core optical waveguide to provide optical coupling between the waveguiding core of the solid core optical waveguide and the waveguiding core of the optical mode field adapter, and the second end of the optical mode field adapter joined to the coupled end of the hollow core optical waveguide to provide optical coupling between the waveguiding core of the hollow core optical waveguide and the waveguiding core of the optical mode field adapter.

Low loss fiber-to-chip interfaces for lithium niobate photonic integrated circuits are provided. An optical circuit includes a waveguide comprising an electro-optical material. The waveguide includes an elevated ridge and a slab underlying the elevated ridge, the elevated ridge and the slab extending along a central axis toward an optical interface. The elevated ridge and the slab each have a plurality of cross-sections along the central axis, each cross-section having a width measured perpendicular to the central axis, wherein the width of elevated ridge is smaller than the width of the slab for every cross-section along the central axis. The elevated ridge includes a tapered portion having a first taper, wherein the cross-section of the elevated portion decreases along the central axis toward the optical interface. The slab includes a tapered portion having a second taper, wherein the cross-section of the slab decreases along the central axis toward the optical interface. The slab extends beyond the elevated ridge along the central axis to the optical interface.

A polarization converter based on taking a high-order TE mode as a transition mode comprises a ridge waveguide (1) and a slab waveguide (2) that are arranged in double layers and varying in width, and a strip waveguide (4) which is varying in width. The ridge waveguide (1) is disposed on the upper end face of the slab waveguide (2), and is aligned with two ends of the slab waveguide (2). The right end of the ridge waveguide (1) and the slab waveguide (2) are connected with the strip waveguide (4) with the varying width. A TM.sub.0 mode enters from the left ends of the ridge waveguide and the slab waveguide, and is converted into a TE.sub.0 mode for output. On the contrary, the TE.sub.0 mode enters from the right end of the strip waveguide and is converted into the TM.sub.0 mode for output.

A data transmission system is disclosed. The data transmission system includes at least one signal processing device, at least one conversion device, at least one antenna device, and at least one flexible printed circuit board. The at least one signal processing device is configured to generate or receive at least one data. The at least one conversion device is configured to transform between the at least one data and an optical signal. The at least one antenna device is configured to obtain the at least one data according to the optical signal, and configured to receive or transmit the at least one data wirelessly. The at least one flexible printed circuit board includes at least one conductive layer and at least one optical waveguide layer. The at least one optical waveguide layer is configured to transmit the optical signal.