A device of collimation of a light beam including a monomode waveguide, a first element of collimation of the light beam parallel to a first plane and a second element of collimation of the light beam parallel to a second plane, the first collimation element coupling the waveguide to the second collimation element.

Provided is a mode equalization filter that reduces a light intensity difference between multiple modes of signal light propagating in a core of a few-mode fiber. The mode equalization filter according to the present invention includes: a collimator lens that collimates the signal light emitted from the few-mode fiber; a partial ND filter including a small dot having small transmittance with respect to the collimated signal light; and condensing lenses that condense the signal light transmitted through the partial ND filter on the few-mode fiber. The small dot having the small transmittance is arranged in a part of the partial ND filter, and the partial ND filter is arranged such that, when the collimated signal light is transmitted, a part of the collimated signal light overlaps with the small dot having the small transmittance.

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 50+2 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.

A mode coupling connector system that includes a first and second fiber connector each coupled to a coupler housing. The first and second fiber connectors are positioned in first and second receiving cavities of the coupler housing, respectively. The first and second fiber connector each have a ferrule with a fiber receiving hole extending from an outer end to an inner end of the ferrule. The fiber receiving hole of the first and second fiber connector are in axial alignment. The mode coupling connector system further includes a mode coupling plate having a phase mask array of a plurality of phase masks. The mode coupling plate is positioned in a plate receiving hole of the coupler housing between the first and second receiving cavity and at least two phase masks of the phase mask array are circumscribed by the fiber receiving hole of both the first and second fiber connector.

An apparatus includes an optical gain fiber having a core, a cladding surrounding the core, the core and cladding defining an optical gain fiber numerical aperture, and a multimode fiber having a core with a larger radius than a radius of the optical gain fiber core, a cladding surrounding the core, the core and cladding of the multimode fiber defining a multimode fiber stable numerical aperture that is larger than the optical gain fiber numerical aperture, the multimode fiber being optically coupled to the optical gain fiber so as to receive an optical beam propagating in the optical gain fiber and to stably propagate the received optical beam in the multimode fiber core with low optical loss associated with the optical coupling.

A free space optical communication system transmits and receives optical signals in a colorless manner using an optical circulator. The system installs the optical circulator with a single mode (SM) fiber at port 1, a double clad (DC) fiber at port 2, and a multimode (MM) fiber at port 3. The system injects a first optical signal into a core of the SM fiber. The system then routes the first optical signal at port 1, using the optical circulator, into a SM core of the DC fiber via Port 2. Further, the system injects a second optical signal into a first cladding of the DC fiber. The system then routes the second optical signal at port 2, using the optical circulator, into the MM fiber via Port 3.

A fiber module (1B) according to the present disclosure includes an input-side optical fiber (11), an output-side optical fiber (12), a ferrule (20) in which the input-side optical fiber and the output-side optical fiber are insertable in both ends and a groove (32) is formed in a direction orthogonal to a longitudinal direction (D1) in the middle of the longitudinal direction, a dielectric multilayer film filter (30) inserted in the groove, and an input-side GI fiber (15) and an output-side GI fiber (16) joined by fusion to respective terminal portions of the input-side optical fiber and the output-side optical fiber. The dielectric multilayer film filter is interposed between an end surface (15f) of the input-side GI fiber and an end surface (16f) of the output-side GI fiber in the longitudinal direction.

A light source includes features configured to compensate for discontinuous solid state sources. The light source can produce a wide color gamut in display, and improved color rendering of tissue under observation by phosphor gap filling with colored LEDs. The light source can include provisions to depart from a white light spectrum to heighten differences in anatomical features or functions. The light source can include provisions to introduce narrow-band solid-state sources for producing false-color and pseudo-color images, with variable color rendering to change the power spectral distribution and to compensate for fiber optic length and fiber optic diameter tip sensing.

A mode coupling connector system that includes a first and second fiber connector each coupled to a coupler housing. The first and second fiber connectors are positioned in first and second receiving cavities of the coupler housing, respectively. The first and second fiber connector each have a ferrule with a fiber receiving hole extending from an outer end to an inner end of the ferrule. The fiber receiving hole of the first and second fiber connector are in axial alignment. The mode coupling connector system further includes a mode coupling plate having a phase mask array of a plurality of phase masks. The mode coupling plate is positioned in a plate receiving hole of the coupler housing between the first and second receiving cavity and at least two phase masks of the phase mask array are circumscribed by the fiber receiving hole of both the first and second fiber connector.

A display device may include a projector coupled to volume Bragg grating (VBG) based pupil-replicating lightguide. The projector may be a scanning projector or a display panel based projector. A lighting unit for the display panel may have spatially variant spectral composition selected to match angular and wavelength selectivity of the VBGs of the pupil-replicating lightguide, thereby improving light utilization efficiency of the display device. In scanning projector implementations, the center wavelength of the scanned light beam may be varied in coordination with the scanning, to achieve the same effect.