Abstract: Systems and methods for network-based ultrasound imaging are provided, which can include a number of features. In some embodiments, an ultrasound imaging system images an object with three-dimensional unfocused pings and obtains digital sample sets from a plurality of receiver elements. A sub-set of the digital sample sets can be electronically transferred to a remote server, where the sub-set can be beamformed to produce a series of two-dimensional image frames. A video stream made up of the series of two-dimensional images frames can then be transferred from the remote server to a display device.

Abstract: An amplified hollow-core fiber (HCF) optical transmission system for low latency communications. The optical transmission system comprises a low-latency amplified HCF cable. The low-latency amplified HCF cable comprises multiple HCF segments (or HCF spans). Between consecutive HCF segments, the system comprises low-latency remote optically pumped amplifiers (ROPAs). Each ROPA comprises a gain fiber, a wavelength division multiplexing (WDM) coupler, and an optical isolator. Preferably, the ROPAs are integrated into the HCF cable. Each ROPA is pumped by a remote optical pump source, which provides pump light to the gain fiber. The gain fiber receives an optical transmission signal from the HCF. The WDM coupler combines the pump light with the optical transmission signal, thereby allowing the gain fiber to amplify the optical transmission signal to an amplified transmission signal. The amplified signal is transmitted to another HCF segment through the optical isolator.

Abstract: In accordance with a plurality of embodiments of the present invention, exemplary systems and articles of manufactures are described herein that are configured to propagate a MM signal from a light source, such as an optical fiber assembly for propagating a multimode (MM) signal from a light source, the optical fiber assembly comprising a multicore fiber (MCF) having a fiber numerical aperture (NA) value, a first core diameter and a first outer diameter (OD), and a combiner including a taper fiber bundle (TFB) portion in communication with the MCF, and at least one pigtail portion in communication with the light source, wherein the combiner propagates the MM signal from the light source, the MM signal having a signal NA value that is less than the fiber NA value such that the MM signal underfills the at least one pigtail portion.

Abstract: An optical fiber amplifier is formed to include a grating structure inscribed within the rare earth-doped gain fiber itself, providing distributed wavelength-dependent filtering (attenuation) and minimizing the need for any type of gain-flattening filter to be used at the output of the amplifier. The grating structure may be of any suitable arrangement that provides the desired loss spectrum, for example, similar to the profile of a prior art discrete GFF. Various types of grating structures that may be used to provide distributed wavelength-dependent filtering along the gain include, but are not limited to, tilted gratings, weak Bragg gratings, long-period grating (LPG), and any suitable combination of these grating structures.

Abstract: An apparatus for fabricating a hollow core optical fiber with a controllable core region (in terms of diameter) is based upon regulating conditions (gas flow, volume, and/or temperature) within the hollow core region during the fiber draw process. The introduction of a gas, or any change in volume or temperature of the hollow core region, allows for the diameter of the hollow core region to self-regulate as a multistructured core rod (MCR) is drawn down into the final hollow core optical fiber structure. This self-regulation provides a core region having a diameter that selected and then stabilized for the duration of the draw process. The inventive apparatus is also useful in controlling the diameter of any selected hollow region of an MCR including, but not limited to, shunts and corner capillaries disposed around the core region.

Abstract: A photoinduced refractive index-changing material is coupled directly to both a first port and a second port. An optical interconnect structure (for optically coupling the first port to the second port) is formable in the photoinduced refractive index-changing material by selectively exposing a portion of the photoinduced refractive index-changing material. The selective exposure induces a refractive index change in the photoinduced refractive index-changing material. The change in refractive index provides the waveguiding properties of the optical interconnect structure.

Abstract: A technique for fabricating a hollow core optical fiber with a controllable core region (in terms of diameter) is based upon regulating conditions (gas flow, volume, and/or temperature) within the hollow core region during the fiber draw process. The introduction of a gas, or any change in volume or temperature of the hollow core region, allows for the diameter of the hollow core region to self-regulate as a multistructured core rod (MCR) is drawn down into the final hollow core optical fiber structure. This self-regulation provides a core region having a diameter that selected and then stabilized for the duration of the draw process. The inventive process is also useful in controlling the diameter of any selected hollow region of an MCR including, but not limited to, shunts and corner capillaries disposed around the core region.

Abstract: An optical probe includes an optical source that generates an optical beam that propagates from a proximal end to a distal end of an optical fiber that imparts a transformation of a spatial profile of the optical beam. An optical control device imparts a compensating spatial profile on the optical beam that at least partially compensates for the transformation of the spatial profile of the optical beam imparted by the optical fiber in response to a control signal from a signal processor. A distal optical source generates a calibration light that propagates through the one or more optical waveguides from the distal end to the proximal end of the optical fiber. An optical detector detects the calibration light and generates electrical signals in response to the detected calibration light.

Abstract: A higher-order mode (HOM) fiber is configured as a polarization-maintaining fiber by including a pair of stress rods at a location within the cladding layer that provides for a sufficient degree of birefringence without unduly comprising the spatial mode profile of the propagating higher-order modes. An optical imaging system utilizing polarization-maintaining HOM fiber allows for different wavelength probe signals to be directed into different modes, useful in applications such as STED microscopy, 2D sensing, and the like.

Abstract: A hollow core optical fiber and cable combination is configured to exhibit minimal SNR and loss degradation. This is achieved by either: (1) reducing the coupling between the fundamental and other (unwanted) modes propagating within the hollow core fiber; or (2) increasing the propagation loss along the alternative. The first approach may be achieved by designing the cable to minimize perturbations and/or designing the hollow core fiber to fully separate the fundamental mode from the unwanted modes so as to reduce coupling into the unwanted modes. Whether through fiber design or cable design, the amount of light coupled into unwanted modes is reduced to acceptable levels. The second approach may be realized through either fiber design and/or cable design to suppress the light in unwanted modes so that an acceptably low level of light is coupled back into the fundamental mode.

Abstract: An optical probe includes an optical source that generates an optical beam that propagates from a proximal end to a distal end of an optical fiber that imparts a transformation of a spatial profile of the optical beam. An optical control device imparts a compensating spatial profile on the optical beam that at least partially compensates for the transformation of the spatial profile of the optical beam imparted by the optical fiber in response to a control signal from a signal processor. A distal optical source generates a calibration light that propagates through the one or more optical waveguides from the distal end to the proximal end of the optical fiber. An optical detector detects the calibration light and generates electrical signals in response to the detected calibration light.

Abstract: An optical system comprising an optical conduit (e.g., gain fiber or rare-earth-doped fiber) with a bend having a bend radius (R). The bend induces a tension and a compression in the fiber core, which results in a corresponding strain (?). The corresponding bend-induced strain impacts the signal properties in the core of the fiber.

Abstract: A hollow core optical fiber and cable combination is configured to exhibit minimal SNR and loss degradation. This is achieved by either: (1) reducing the coupling between the fundamental and other (unwanted) modes propagating within the hollow core fiber; or (2) increasing the propagation loss along the alternative. The first approach may be achieved by designing the cable to minimize perturbations and/or designing the hollow core fiber to fully separate the fundamental mode from the unwanted modes so as to reduce coupling into the unwanted modes. Whether through fiber design or cable design, the amount of light coupled into unwanted modes is reduced to acceptable levels. The second approach may be realized through either fiber design and/or cable design to suppress the light in unwanted modes so that an acceptably low level of light is coupled back into the fundamental mode.

Abstract: A hollow core optical fiber and cable combination is configured to exhibit minimal SNR and loss degradation. This is achieved by either: (1) reducing the coupling between the fundamental and other (unwanted) modes propagating within the hollow core fiber, or (2) increasing the propagation loss along the alternative. The first approach may be achieved by designing the cable to minimize perturbations and/or designing the hollow core fiber to fully separate the fundamental mode from the unwanted modes so as to reduce coupling into the unwanted modes. Whether through fiber design or cable design, the amount of light coupled into unwanted modes is reduced to acceptable levels. The second approach may be realized through either fiber design and/or cable design to suppress the light in unwanted modes so that an acceptably low level of light is coupled back into the fundamental mode.

Abstract: A process of fabricating the microstructure core rod preform used in the fabrication of a hollow core optical fiber includes the step of applying external pressure to selected hollow regions during the drawing of the preform from the initial assembly of capillary tubes. The application of pressure assists the selected hollow regions in maintaining their shape as much as possible during draw, and reduces distortions in the microstructure cells in close proximity to the core by controlling glass distribution during MCR draw.

Abstract: A technique for fabricating a hollow core optical fiber with a controllable core region (in terms of diameter) is based upon regulating conditions (gas flow, volume, and/or temperature) within the hollow core region during the fiber draw process. The introduction of a gas, or any change in volume or temperature of the hollow core region, allows for the diameter of the hollow core region to self-regulate as a multistructured core rod (MCR) is drawn down into the final hollow core optical fiber structure. This self-regulation provides a core region having a diameter that selected and then stabilized for the duration of the draw process. The inventive process is also useful in controlling the diameter of any selected hollow region of an MCR including, but not limited to, shunts and corner capillaries disposed around the core region.

Abstract: A hollow core optical fiber and cable combination is configured to exhibit minimal SNR and loss degradation. This is achieved by either: (1) reducing the coupling between the fundamental and other (unwanted) modes propagating within the hollow core fiber, or (2) increasing the propagation loss along the alternative. The first approach may be achieved by designing the cable to minimize perturbations and/or designing the hollow core fiber to fully separate the fundamental mode from the unwanted modes so as to reduce coupling into the unwanted modes. Whether through fiber design or cable design, the amount of light coupled into unwanted modes is reduced to acceptable levels. The second approach may be realized through either fiber design and/or cable design to suppress the light in unwanted modes so that an acceptably low level of light is coupled back into the fundamental mode.

Abstract: A higher-order mode (HOM) fiber is configured as a polarization-maintaining fiber by including a pair of stress rods at a location within the cladding layer that provides for a sufficient degree of birefringence without unduly comprising the spatial mode profile of the propagating higher-order modes. An optical imaging system utilizing polarization-maintaining HOM fiber allows for different wavelength probe signals to be directed into different modes, useful in applications such as STED microscopy, 2D sensing, and the like.

Abstract: A fiber amplifier has a first amplification stage and a second amplification stage. The first amplification stage comprises a first gain fiber that is configured to receive, at its input end, a signal light and a pump light. The first gain fiber uses a portion of the pump light to provide first-stage amplification to the signal light. The second amplification stage comprises a second gain fiber that is configured to receive, at its input end, the first-stage-amplified signal light and residual pump light. The second gain fiber uses the residual pump light to provide second-stage amplification of the first-stage-amplified signal light and to provide, at its output end, the second-stage amplified signal light.

Abstract: A higher-order mode (HOM) fiber is configured as a polarization-maintaining fiber by including a pair of stress rods at a location within the cladding layer that provides for a sufficient degree of birefringence without unduly comprising the spatial mode profile of the propagating higher-order modes. Long-period gratings are used as mode couplers at the input and output of the PM-HOM fiber, where the gratings are formed by exposing areas of the core region orthogonal to the position of the stress rods. The diameter of the stress rods (D) and displacement of the rods from the center of the core region (R1) are controlled to yield a configuration with an acceptable birefringence and polarization extinction ratio (PER) within the HOM fiber, even in situations where the fiber is bent (a bend radius less than 50 cm).