Abstract: An acoustic sensor comprises a sensing head comprising an optical fiber having a tip. A graphene diaphragm is disposed on the tip and is configured to vibrate in response to an acoustic signal. A fiber laser is optically coupled to the sensing head. The fiber laser comprises a first set of fiber Bragg gratings and a second set of fiber Bragg gratings. A gap is present between the first set and the second set of fiber Bragg gratings. The fiber laser is configured to generate a sensing optical signal having a first intensity in response to an excitation optical signal, the sensing optical signal impinging on the graphene diaphragm such that a feedback optical signal is reflected from the graphene diaphragm towards the fiber laser and has and has a second intensity modulated by the vibration of the graphene diaphragm that corresponds to the acoustic signal.

Abstract: An acoustic sensor comprises a sensing head comprising an optical fiber having a tip. A graphene diaphragm is disposed on the tip and is configured to vibrate in response to an acoustic signal. A fiber laser is optically coupled to the sensing head. The fiber laser comprises a first set of fiber Bragg gratings and a second set of fiber Bragg gratings. A gap is present between the first set and the second set of fiber Bragg gratings. The fiber laser is configured to generate a sensing optical signal having a first intensity in response to an excitation optical signal, the sensing optical signal impinging on the graphene diaphragm such that a feedback optical signal is reflected from the graphene diaphragm towards the fiber laser and has and has a second intensity modulated by the vibration of the graphene diaphragm that corresponds to the acoustic signal.

Abstract: A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

Abstract: A millimeter wave measurement system has been developed for remote detection of airborne nuclear radiation, based on electromagnetic scattering from radiation-induced ionization in air. Specifically, methods of monitoring radiation-induced ionization of air have been investigated, and the ionized air has been identified as a source of millimeter wave radar reflection, which can be utilized to determine the size and strength of a radiation source.

Abstract: A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is positioned to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

Abstract: A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

Abstract: A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is position to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

Abstract: A millimeter wave measurement system has been developed for remote detection of airborne nuclear radiation, based on electromagnetic scattering from radiation-induced ionization in air. Specifically, methods of monitoring radiation-induced ionization of air have been investigated, and the ionized air has been identified as a source of millimeter wave radar reflection, which can be utilized to determine the size and strength of a radiation source.