Abstract: A large-area, waveguide-based, high-speed ultraviolet and visible light photodetector system for optical wireless communication includes a substrate; plural, parallel, waveguides formed directly on the substrate and including a high quantum-yield wavelength-converting material of semiconductor nature; an optical coupling system optically connected to each one of the plural, parallel, waveguides; and a photodetector optically connected to the optical coupling system and configured to detect an outgoing light. The wavelength-converting material converts a first wavelength of an incoming light at high-speed, received by the plural, parallel, waveguides, into a second wavelength of the outgoing light. The first wavelength is different from the second wavelength, and the first and second wavelengths are between 200 and 800 nm.

Abstract: A hybrid sensing-communication system includes a multicore optical fiber that includes first and second cores, a first communication device optically coupled to a first end of the first core of the multicore optical fiber, a second communication device optically coupled to a second end of the first core of the multicore optical fiber, a first sensing device optically coupled to a first end of the second core of the multicore optical fiber, and a second sensing device optically coupled to a second end of the second core of the multicore optical fiber. The first and second communication devices exclusively exchange communication data along the first core, the first and second sensing devices exclusively exchange sensing data along the second core, and the communication data is different from the sensing data.

Abstract: An optical converting receiver, for changing a visible light beam into a near-infrared, NIR, light beam, includes a substrate, a non-silicon-based optical element located on the substrate and configured to receive the visible light beam and convert the visible light beam into the NIR light beam, a silicon-based optical element located on the substrate and optically coupled to the non-silicon-based optical element, the silicon-based optical element being configured to propagate the NIR light beam, and a photodetector located on the substrate and optically coupled to the silicon-based optical element, the photodetector being configured to convert the NIR light beam into an electrical signal.

Abstract: A communication system includes a first communication gateway arranged proximate to a surface of a body of water and an underwater communication gateway. The underwater communication gateway is configured to receive data from a first underwater communication device using radio frequencies and the ethernet data link layer protocol, to convert the data received from the first underwater communication device from the ethernet data link layer protocol to the second data link layer protocol, and to transmit, using optical radiation and the second data link layer protocol, the data converted by the underwater communication gateway to the first communication gateway. The first communication gateway is configured to convert the data transmitted by the underwater communication gateway from the second data link layer protocol to the ethernet data link layer protocol, and to transmit, using the ethernet data link layer protocol, the data converted by the first communication device to a further communication device.

Abstract: An optical fiber distributed acoustic sensor (DAS) system for detecting a red palm weevil and/or its larvae inside a tree. The system includes an optical fiber that is configured to be placed next to a tree; and a DAS box optically connected to the optical fiber and configured to receive a reflected light from the optical fiber. The DAS box includes electronics that extracts from the reflected light a frequency in a range of [400 Hz, 4 kHz], and sends a message indicating a presence of the red palm weevil and/or its larvae inside the tree.

Abstract: A free node to be deployed underwater for omnidirectional energy and data harvesting includes a housing that forms a sealed chamber; a wavelength-changing layer attached to an outside of the housing and configured to receive a first optical signal having a first wavelength range and to emit a second optical signal having a second wavelength range, different from the first wavelength range, wherein the first optical signal includes encoded data; a flexible solar cell wrapped around the housing, the flexible solar cell being configured to receive the second optical signal and generate an electrical signal; an energy storage module located in the chamber and configured to store electrical energy associated with the electrical signal; and a decoder located in the chamber and configured to receive the electrical signal and decode the encoded data. The first wavelength range is ultraviolet light and the second wavelength range is visible or infrared light.

Abstract: The subject matter of this specification can be embodied in, among other things, a method for remotely sensing vibration includes transmitting a collection of optical pulses through an optical fiber at a predetermined frequency, detecting a collection of backscattered Rayleigh traces from the optical fiber based on a vibration of the optical fiber at a vibration frequency at a location along the optical fiber, determining a normalized differential trace based on the collection of Rayleigh traces, determining, based on the normalized differential trace, the location in the optical fiber of the vibration, and determining, based on the raw Rayleigh traces, the vibration frequency.

Abstract: A fiber optic distributed acoustic sensing (DAS) system for detecting a red palm weevil (RPW) includes an optical fiber configured to be wrapped around a tree and a DAS box connected to the optical fiber. The DAS box includes a processing unit that is configured to receive a filtered Rayleigh signal reflected by the optical fiber, and run the filtered Rayleigh signal through a neural network system to determine a presence of the RPW in the tree.

Abstract: A hybrid sensing-communication system includes a multicore optical fiber that includes first and second cores, a first communication device optically coupled to a first end of the first core of the multicore optical fiber, a second communication device optically coupled to a second end of the first core of the multicore optical fiber, a first sensing device optically coupled to a first end of the second core of the multicore optical fiber, and a second sensing device optically coupled to a second end of the second core of the multicore optical fiber. The first and second communication devices exclusively exchange communication data along the first core, the first and second sensing devices exclusively exchange sensing data along the second core, and the communication data is different from the sensing data.

Abstract: Systems and methods include a method for overcoming optical time domain reflectometry (OTDR) dead zone limitations by using a few-mode fiber (FMF). Optical pulses are transmitted by a transmitter of an OTDR system through a mode MUX/DEMUX into an FMF. Light signals directed by the FMF in a backward direction through the mode MUX/DEMUX are received by the OTDR system through N single-mode fiber (SMF) ports corresponding to N modes in the FMF. Light signals from N?1 dead-zone-free SMF ports are collected by the OTDR system. Losses are measured and faults are located in the FMF based at least on the light signals.

Abstract: A communication system includes a first communication gateway arranged proximate to a surface of a body of water and an underwater communication gateway. The underwater communication gateway is configured to receive data from a first underwater communication device using radio frequencies and the ethernet data link layer protocol, to convert the data received from the first underwater communication device from the ethernet data link layer protocol to the second data link layer protocol, and to transmit, using optical radiation and the second data link layer protocol, the data converted by the underwater communication gateway to the first communication gateway. The first communication gateway is configured to convert the data transmitted by the underwater communication gateway from the second data link layer protocol to the ethernet data link layer protocol, and to transmit, using the ethernet data link layer protocol, the data converted by the first communication device to a further communication device.

Abstract: A plastic optical fiber communication system includes a light source that emits a first signal having a first wavelength in a visible light spectrum, the first signal being encoded with information at a high data-rate of 0.1 to 10 Gbit/s; a pump laser system that emits a pump laser light having a second wavelength, different from the first wavelength; a perovskite-doped optical fiber excited by the pump laser light to generate an amplified spontaneous emission spectrum that encompasses the first wavelength so as to receive and amplify the first signal for generating an amplified output signal having the first wavelength; and a photodetector optically coupled to the perovskite-doped optical fiber, and configured to receive the amplified output signal at the high data-rate of 0.1 to 10 Gbit/s. The amplified output signal is encoded with the information.

Abstract: A method for transmitting information across a water-air interface with a ultraviolet (UV) beam, the method including emitting the UV beam in a first medium, with a first optical wireless communication device; measuring a scintillation index of the UV beam in a second medium, different from the first medium, at a second optical wireless communication device; selecting, based on a value of the scintillation index, a modulation scheme for the UV beam; and modulating the UV beam with the selected modulation scheme. The UV beam has a wavelength in a range of 100 to 400 nm.

Abstract: A free node to be deployed underwater for omnidirectional energy and data harvesting includes a housing that forms a sealed chamber; a wavelength-changing layer attached to an outside of the housing and configured to receive a first optical signal having a first wavelength range and to emit a second optical signal having a second wavelength range, different from the first wavelength range, wherein the first optical signal includes encoded data; a flexible solar cell wrapped around the housing, the flexible solar cell being configured to receive the second optical signal and generate an electrical signal; an energy storage module located in the chamber and configured to store electrical energy associated with the electrical signal; and a decoder located in the chamber and configured to receive the electrical signal and decode the encoded data. The first wavelength range is ultraviolet light and the second wavelength range is visible or infrared light.

Abstract: A method for determining tree infestation includes placing an optical fiber around a trunk of a tree; recording with a distributed acoustic sensor (DAS) box a Rayleigh signal reflected from the tree, along the optical fiber; processing the Rayleigh signal to obtain a processed signal; calculating a signal-to-noise ratio (SNR) of the processed signal for the tree; and comparing the SNR to a threshold value and counting an alarm if the SNR is larger than the threshold value. The SNR is defined as a ratio between (1) a maximum value of a processed signal and (2) a minimum value of the processed signal.

Abstract: An integrated system for detecting a red palm weevil (RPW), farm fire, and soil moisture includes an optical fiber configured to be extending to a tree, and a distributed acoustic sensor (DAS) box connected to the optical fiber. The DAS box is configured to process first to third different optical signals reflected from the optical fiber, to determine a presence of the RPW from the first optical signal, a temperature at a location along the optical fiber from the second optical signals, and a moisture at a location around the tree from the third optical signal.

Abstract: A method for transmitting information across a water-air interface with a ultraviolet (UV) beam, the method including emitting the UV beam in a first medium, with a first optical wireless communication device; measuring a scintillation index of the UV beam in a second medium, different from the first medium, at a second optical wireless communication device; selecting, based on a value of the scintillation index, a modulation scheme for the UV beam; and modulating the UV beam with the selected modulation scheme. The UV beam has a wavelength in a range of 100 to 400 nm.

Abstract: A large-area, waveguide-based, high-speed ultraviolet and visible light photodetector system for optical wireless communication includes a substrate; plural, parallel, waveguides formed directly on the substrate and including a high quantum-yield wavelength-converting material of semiconductor nature; an optical coupling system optically connected to each one of the plural, parallel, waveguides; and a photodetector optically connected to the optical coupling system and configured to detect an outgoing light. The wavelength-converting material converts a first wavelength of an incoming light at high-speed, received by the plural, parallel, waveguides, into a second wavelength of the outgoing light. The first wavelength is different from the second wavelength, and the first and second wavelengths are between 200 and 800 nm.

Abstract: A plastic optical fiber communication system includes a light source that emits a first signal having a first wavelength in a visible light spectrum, the first signal being encoded with information at a high data-rate of 0.1 to 10 Gbit/s; a pump laser system that emits a pump laser light having a second wavelength, different from the first wavelength; a perovskite-doped optical fiber excited by the pump laser light to generate an amplified spontaneous emission spectrum that encompasses the first wavelength so as to receive and amplify the first signal for generating an amplified output signal having the first wavelength; and a photodetector optically coupled to the perovskite-doped optical fiber, and configured to receive the amplified output signal at the high data-rate of 0.1 to 10 Gbit/s. The amplified output signal is encoded with the information.

Abstract: A tunable laser system includes a laser diode producing a light beam having a plurality of frequencies in a visible portion of a light spectrum. A collimating lens arranged in front of the laser diode produces a collimated light beam from the light beam produced by the laser diode. A partial reflector arranged in a path of the collimated laser beam reflects a first portion of the collimated light beam and passes a second portion of the collimated light beam as an output light beam. The first portion of the collimated light beam enters the laser diode and mixes with the plurality of frequencies of the light beam produced by the laser diode so that the laser diode produces a self-injection-locked light beam including at least two frequencies having a frequency difference in a terahertz frequency range. A translational stage adjusts a distance between the laser diode and the partial reflector. The laser diode or the partial reflector is mounted on the translational stage.