In some implementations, a device may generate a data set including at least modal gain values and modal loss values for a semiconductor optical amplifier (SOA) slice. The device may determine, based on the data set, respective widths for a plurality of slices of an SOA using an autoregressive model. A width, of the respective widths, for a slice, of the plurality of slices, may be associated with a maximum conversion efficiency achievable for the slice at a given current density. The device may generate information indicating a geometry for the SOA based on the respective widths for the plurality of slices.

A room-temperature semiconductor maser, including a first matching network, a second matching network, a heterojunction-containing transistor, and a resonant network. The output end of the first matching network is connected to the drain of the heterojunction-containing transistor. The input end of the second matching network is connected to the source of the heterojunction-containing transistor. The gate of the heterojunction-containing transistor is connected to the resonant network. The pumped microwaves are fed into the input end of the first matching network.

Embodiments of the invention describe polarization insensitive optical devices utilizing polarization sensitive components. Light comprising at least one polarization state is received, and embodiments of the invention select a first optical path for light comprising a first polarization state or a second optical path for light comprising a second polarization state orthogonal to the first polarization state. The optical paths include components to at least amplify and/or modulate light comprising the first polarization state; the second optical path includes a polarization rotator to rotate light comprising the second polarization state to the first polarization state. Embodiments of the invention further describe optical devices including a polarization mode converter to convert light comprising a first and a second polarization state to light comprising different spatial modes of the first polarization state; light comprising the different spatial modes of the first polarization state is subsequently amplified and modulated.

An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier. The optical amplifier includes: a main optical fiber that includes a core transmitting signal light, an inner cladding portion formed around an outer periphery of the core and having a refractive index lower than a refractive index of the core, and an outer cladding portion formed around an outer periphery of the inner cladding portion and having a refractive index lower than the refractive index of the inner cladding portion, a part of the outer cladding portion of which in a longitudinal direction being removed; and at least one pump-light input-output optical fiber that is fusion-spliced to the inner cladding portion of the main optical fiber at the portion where the outer cladding portion is removed, an average refractive index of which in a contact region where the pump-light input-output optical fiber is in contact with the inner cladding portion being larger than the refractive index of the inner cladding portion. Pump-light propagating in the pump-light input-output optical fiber is coupled to the inner cladding portion from the contact region and propagates in the inner cladding portion, or the pump-light propagating in the inner cladding portion is coupled to the pump-light input-output optical fiber from the contact region and propagates in the pump-light input-output optical fiber.

Depolarized fiber lasers and respective methods are provided for increasing the SBS (stimulated Brillouin scattering) threshold. The laser source is constructed by a frequency-broadened seed source having a frequency bandwidth of less than 50 GHz, and the depolarization of the seed source is carried out at time scales shorter than 10 ns. At least one amplifier is configured to receive and amplify radiation from the frequency-broadened seed source and deliver the amplified radiation in the optical fiber. Depolarization may be achieved in various ways (e.g., using an interferometer with added length to one arm) and is kept at time scales shorter than tens of nanoseconds, typically shorter than 5-10 ns, which distinguish it from random polarization having polarization changes at longer time scales. Polarization maintaining fibers may be used to further increase the SBS by separating the polarizations states.

A room-temperature semiconductor maser, including a first matching network, a second matching network, a heterojunction-containing transistor, and a resonant network. The output end of the first matching network is connected to the drain of the heterojunction-containing transistor. The input end of the second matching network is connected to the source of the heterojunction-containing transistor. The gate of the heterojunction-containing transistor is connected to the resonant network. The pumped microwaves are fed into the input end of the first matching network.

Embodiments of the invention describe polarization insensitive optical devices utilizing polarization sensitive components. Light comprising at least one polarization state is received, and embodiments of the invention select a first optical path for light comprising a first polarization state or a second optical path for light comprising a second polarization state orthogonal to the first polarization state. The optical paths include components to at least amplify and/or modulate light comprising the first polarization state; the second optical path includes a polarization rotator to rotate light comprising the second polarization state to the first polarization state. Embodiments of the invention further describe optical devices including a polarization mode converter to convert light comprising a first and a second polarization state to light comprising different spatial modes of the first polarization state; light comprising the different spatial modes of the first polarization state is subsequently amplified and modulated.

An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier. The optical amplifier includes: a main optical fiber that includes a core transmitting signal light, an inner cladding portion formed around an outer periphery of the core and having a refractive index lower than a refractive index of the core, and an outer cladding portion formed around an outer periphery of the inner cladding portion and having a refractive index lower than the refractive index of the inner cladding portion, a part of the outer cladding portion of which in a longitudinal direction being removed; and at least one pump-light input-output optical fiber that is fusion-spliced to the inner cladding portion of the main optical fiber at the portion where the outer cladding portion is removed, an average refractive index of which in a contact region where the pump-light input-output optical fiber is in contact with the inner cladding portion being larger than the refractive index of the inner cladding portion. Pump-light propagating in the pump-light input-output optical fiber is coupled to the inner cladding portion from the contact region and propagates in the inner cladding portion, or the pump-light propagating in the inner cladding portion is coupled to the pump-light input-output optical fiber from the contact region and propagates in the pump-light input-output optical fiber.

Embodiments of the invention describe polarization insensitive optical devices utilizing polarization sensitive components. Light comprising at least one polarization state is received, and embodiments of the invention select a first optical path for light comprising a first polarization state or a second optical path for light comprising a second polarization state orthogonal to the first polarization state. The optical paths include components to at least amplify and/or modulate light comprising the first polarization state; the second optical path includes a polarization rotator to rotate light comprising the second polarization state to the first polarization state. Embodiments of the invention further describe optical devices including a polarization mode converter to convert light comprising a first and a second polarization state to light comprising different spatial modes of the first polarization state; light comprising the different spatial modes of the first polarization state is subsequently amplified and modulated.

The present invention provides an optical amplification apparatus for amplifying light from a light source, comprising: a combiner configured to output light received at a first input port from the light source as first light, and output light received at a second input port as second light; an optical amplifier configured to amplify an intensity of each of the first light and the second light output from the combiner; a splitter configured to output the received first light from a first output port, and output the received second light from a second output port; and an optical modulator configured to attenuate an intensity of light output from the first output port of the splitter, wherein the light output from the first output port of the splitter is received at the second input port of the combiner via the optical modulator.