Nonreciprocal optical transmission devices and optical apparatuses including the nonreciprocal optical transmission devices are provided. A nonreciprocal optical transmission device includes an optical input portion, an optical output portion, and an intermediate connecting portion interposed between the optical input portion and the optical output portion, and comprising optical waveguides. A complex refractive index of any one or any combination of the optical waveguides changes between the optical input portion and the optical output portion, and a transmission direction of light through the nonreciprocal optical transmission device is controlled by a change in the complex refractive index.

Techniques are described for a device that includes an optical channel configured to transport an optical signal. The device further includes a magnetic material with low optical absorption through which a portion of the optical signal is configured to flow. The magnetic material is configured to receive an electrical signal that sets a magnetization state of the magnetic material. The magnetic material is further configured to modulate, based on the magnetization state, the portion of the optical signal flowing though the magnetic material.

Techniques are described for a device that includes an optical channel configured to transport an optical signal. The device further includes a magnetic material with low optical absorption through which a portion of the optical signal is configured to flow. The magnetic material is configured to receive an electrical signal that sets a magnetization state of the magnetic material. The magnetic material is further configured to modulate, based on the magnetization state, the portion of the optical signal flowing though the magnetic material.

A light isolator member of an embodiment of the present invention is configured to be joined to another light isolator member to serve as a part of a light isolator, the light isolator member including: a lens surface disposed in a first surface; a transmission surface disposed at a position corresponding to the lens surface in a second surface on a side opposite to the first surface; and a fitting part disposed in the second surface, the fitting part being configured for fitting to the other light isolator member.

The present invention is based on a two-dimensional photonic crystal in which defects are inserted in a controlled manner, has the main function of division of the power of an input signal, excited in one of its six waveguides, among other three waveguides (output ones), while keeping isolation of the input port by means of two other waveguides. The operating principle of the device is based on the alignment of a dipole mode excited in the resonant cavity, in such a way that the nodes of this mode are oriented in the direction of two waveguides, so that these waveguides are not excited. Due to this alignment, each of the three output waveguides receive about one third of the power of input signal. The orientation of dipole mode is controlled by the applied DC magnetic field and the physical and geometrical parameters of the resonator.

The present invention is based on a two-dimensional photonic crystal in which defects are inserted in a controlled manner, has the main function of division of the power of an input signal, excited in one of its six waveguides, among other three waveguides (output ones), while keeping isolation of the input port by means of two other waveguides. The operating principle of the device is based on the alignment of a dipole mode excited in the resonant cavity, in such a way that the nodes of this mode are oriented in the direction of two waveguides, so that these waveguides are not excited. Due to this alignment, each of the three output waveguides receive about one third of the power of input signal. The orientation of dipole mode is controlled by the applied DC magnetic field and the physical and geometrical parameters of the resonator.

A two-dimensional photonic crystal in which are inserted four waveguides and a resonant cavity. Owing to the existence of the photonic band gap, an electromagnetic signal propagating through the device is confined within the guides and the cavity and, through the adjustment of the orientation of a dipole mode generated within the cavity, is able to function in three distinct regimes. In regime 1, subjected to an external DC magnetic field +H0, it functions as a two-way divider, with isolation of the input relative to the two outputs, and, upon reversal of the field signal, it functions as an optical key. In regime 2, with the use of a DC magnetic field −H0, it functions as a waveguide bender, with the input isolated from the output, and, upon reversal of the field signal, functions as an optical key. In regime 3, subject to the application of an external DC magnetic field +H1, the device functions as a three-way divider.

A compact six-port Photonic Crystal (PhC) circulator includes a hexagonal PhC branch waveguide and six waveguide ports, wherein six PhC branch waveguides respectively correspond to the six waveguide ports, and the six waveguide ports respectively are symmetrically distributed at the periphery of PhCs. One second dielectric material column is arranged at the center of the hexagonal PhC waveguide. Six identical magneto-optical material columns respectively are arranged at first adjacent positions of the second dielectric material column. Six identical third dielectric material columns respectively are arranged at second adjacent positions of the second dielectric material column. An electromagnetic signal is inputted from any one of the waveguide ports and is outputted from the next waveguide port adjacent thereto, while the remaining waveguide ports are in a signal isolated state, thus forming unidirectional circular transmission.

Embodiments herein relate to photonic integrated circuits with an on-chip optical isolator. A photonic transmitter chip may include a laser and an on-chip isolator optically coupled with the laser that includes an optical waveguide having a section coupled with a magneto-optic liquid phase epitaxy grown garnet film. In some embodiments, a cladding may be coupled with the garnet film, the on-chip isolator may be arranged in a Mach-Zehnder interferometer configuration, the waveguide may include one or more polarization rotators, and/or the garnet film may be formed of a material from a rare-earth garnet family. Other embodiments may be described and/or claimed.

Methods, systems, and apparatus, for optical communication. One apparatus includes a Fabry-Perot (FP) laser diode assembly coupled to a first port of a circulator; an optical amplifier coupled to a second port of the circulator; a wavelength division multiplexer (WDM) filter coupled to a third port of the circulator; and a Faraday rotator mirror coupled to the WDM filter.