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.

An optical coupling apparatus includes: a coupling and polarization beamsplitter, a phase shifter, a 22 adjustable beamsplitter, a photoelectric detector, and a microprocessor. Light in any polarization direction can be coupled from an optical fiber into a waveguide, an extra insertion loss is small, intrinsic insertion losses for light in different polarization directions are the same, a structure is simple, and miniaturization is easy to be implemented.

Apparatus for laser processing a material (11), which apparatus comprises an optical fibre (2), at least one squeezing mechanism (3), and a lens (4), wherein: the optical fibre (2) is a multimode optical fibre; the optical fibre (2) is such that laser radiation (13) is able to propagate along the optical fibre (2) in a first optical mode (21) and in a second optical mode (22); the squeezing mechanism (3) comprises at least one periodic surface (6) defined by a pitch (7); and the periodic surface (6) is located adjacent to the optical fibre (2); and the apparatus is characterized in that: the pitch (7) couples the first optical mode (21) and the second optical mode C(22) together; the first optical mode (21) is defined by a first mode order (24), and the second optical mode (22) is defined by a second O mode order (25) which is higher than the first mode order (24); the squeezing mechanism (3) is configured to squeeze the periodic surface (6) and the optical fibre (2) together with a squeezing force (12), thereby coupling the first optical mode (21) to the second optical mode (22); the lens (4) is defined by a front focal plane (14) and a rear focal plane (15); the first optical mode (21) is defined by a Rayleigh length (217); and the lens (4) is located within two of the Rayleigh lengths (217) from the distal end (16) of the optical fibre (2).

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.

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.

In one example, an optical device may include a waveguide having a core index of refraction that decreases along a length of the waveguide and an edge index of refraction of the waveguide that is constant along the length of the waveguide. The central rays of the optical signals travelling through the waveguide may be refracted towards higher radii while the outer rays propagate unaffected. The optical device may decrease dispersion of the optical signals travelling through an optical fiber.

Some embodiments of the disclosure relate to an optical transmission system that operates at a wavelength in the range from 950 nm to 1600 nm and that employs a single-mode optical transmitter and an optical receiver optically coupled to respective ends of a multimode fiber designed for 850 nm multimode operation. The optical transmission system also employs at least one single mode fiber situated within the optical pathway between the optical transmitter and the receiver and coupled to the multimode fiber.

Some embodiments of the disclosure relate to an optical transmission system that operates at a wavelength in the range from 950 nm to 1600 nm and that employs a single-mode optical transmitter and an optical receiver optically coupled to respective ends of a multimode fiber designed for 850 nm multimode operation. The optical transmission system also employs at least one single mode fiber situated within the optical pathway between the optical transmitter and the receiver and coupled to the multimode fiber.

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 patch cord for transmitting between a single mode fiber (SMF) and a multi-mode fiber (MMFs) has a MMF, SMF, and a photonic crystal fiber (PCF) with a hollow core placed between the SMF and MMF. A mode field diameter (MFD) of the PCF hollow core section is in the range of 16 to 19 microns, the length of the PCF is between 1 cm to 10 cm, the MMF has 502 microns core diameter, the SMF has a 6-9 microns core diameter, and the coupling between the PCF mode to the MMF fundamental mode is maximized.