Abstract: Performance improvement of an all-optical analog-to-digital converter (AOADC) addresses both RF and optical modeling of a leaky waveguide based optical spatial light modulator (SLM) using electro-optic (E-O) material. The E-O polymer provides improved sensitivity for SLM and achieves a broader bandwidth due to better velocity matching between RF and optical waves.

Abstract: A tunable multi-mode laser is configured to generate a multi-mode optical signal at a tuned wavelength. The laser includes a semiconductor optical gain region, a feedback region, and a phase modulation region between the gain and feedback regions. Each of the regions may be monolithically integrated. A feedback loop is coupled to the tunable laser to receive the optical signal and includes at least one delay line. The delay line may also be monolithically integrated. An output of the delay line is fed back to the tunable multi-mode laser in order to provide at least one of self-injection locking and self-phase locked looping for the multi-mode tunable laser. Each of the optical gain region and phase modulation region of the laser is biased by the output of the delay line in order to reduce phase drift of the optical signal.

Abstract: Low phase noise signal generated in a small structure is required for communication and high-resolution imaging. A DBR based multi-mode laser is combined with mode-locking method to build frequency stabilized and tunable RF signal generator. The number of the output modes from each laser is adjusted using reflecting bandwidth of distributed Bragg reflector and electro-absorption (EA) modulator for amplitude control, while the phase section in integrated laser system provides frequency tuning. Mode-locking of 60 laser modes results in a highly frequency stable 10 GHz RF beat-notes with a calculated phase noise of ?150 dBc/Hz at 10 kHz offset frequency.

Abstract: Low phase noise signal generated in a small structure is required for communication and high-resolution imaging. A DBR based multi-mode laser is combined with mode-locking method to build frequency stabilized and tunable RF signal generator. The number of the output modes from each laser is adjusted using reflecting bandwidth of distributed Bragg reflector and electro-absorption (EA) modulator for amplitude control, while the phase section in integrated laser system provides frequency tuning. Mode-locking of 60 laser modes results in a highly frequency stable 10 GHz RF beat-notes with a calculated phase noise of ?150 dBc/Hz at 10 kHz offset frequency.

Abstract: A tunable multi-mode laser is configured to generate a multi-mode optical signal at a tuned wavelength. The laser includes a semiconductor optical gain region, a feedback region, and a phase modulation region between the gain and feedback regions. Each of the regions may be monolithically integrated. A feedback loop is coupled to the tunable laser to receive the optical signal and includes at least one delay line. The delay line may also be monolithically integrated. An output of the delay line is fed back to the tunable multi-mode laser in order to provide at least one of self-injection locking and self-phase locked looping for the multi-mode tunable laser. Each of the optical gain region and phase modulation region of the laser is biased by the output of the delay line in order to reduce phase drift of the optical signal.

Abstract: Performance improvement of an all-optical analog-to-digital converter (AOADC) addresses both RF and optical modeling of a leaky waveguide based optical spatial light modulator (SLM) using electro-optic (E-O) material. The E-O polymer provides improved sensitivity for SLM and achieves a broader bandwidth due to better velocity matching between RF and optical waves.

Abstract: The fiber optic probe detects changes in ultrasound pressure in an immersion medium such as a liquid, a gas, or a solid, where the system includes an optical fiber probe having a fiber of the probe has a highly doped (or regular) core with a diameter in the range 5 to 10 ?m and a clad diameter equal to or more than 50 ?m; and the optical fiber tip has been modified in a D-shaped (or V-shaped) structure where the clad material has been removed from one side of the cylindrical fiber to the surface of the fiber core; then, this modified region of the fiber is coated, with a very thin layer of a metallic material, ranging from 3 to 10 nm.

Abstract: The fiber optic probe detects changes in ultrasound pressure in an immersion medium such as a liquid, a gas, or a solid, where the system includes an optical fiber probe having a fiber of the probe has a highly doped (or regular) core with a diameter in the range 5 to 10 ?m and a clad diameter equal to or more than 50 ?m; and the optical fiber tip has been modified in a D-shaped (or V-shaped) structure where the clad material has been removed from one side of the cylindrical fiber to the surface of the fiber core; then, this modified region of the fiber is coated, with a very thin layer of a metallic material, ranging from 3 to 10 nm.

Abstract: A sensing method is based on using a special fiberoptic probe for detection of acoustic/ultrasound pressure in an immersion medium. The developed system is highly sensitive in detecting ultrasound waves up to 100 MHz, for imaging of micro structures and more. For applications up to 100 MHz, without spatial averaging corrections, the probe tip is modified by reducing the fiber diameter to 7 um or less. Also, to maximize acousto-optic interaction, the probe tip, not just its end face, may be coated with a thin layer of metallic material. This thin film coating satisfies partial transparency of the metallic coating. The coating thickness may range from 2 nm to 10 nm or others depending on the type of the coating material. The probe detects the pressure of acoustic and/or ultrasound waves propagating within an immersion medium, whenever the probe tip is immersed inside the medium, and having a reasonable immersion contact surface.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: A sensing method is based on using a special fiberoptic probe for detection of acoustic/ultrasound pressure in an immersion medium. The developed system is highly sensitive in detecting ultrasound waves up to 100 MHz, for imaging of micro structures and more. For applications up to 100 MHz, without spatial averaging corrections, the probe tip is modified by reducing the fiber diameter to 7 um or less. Also, to maximize acousto-optic interaction, the probe tip, not just its end face, may be coated with a thin layer of metallic material. This thin film coating satisfies partial transparency of the metallic coating. The coating thickness may range from 2 nm to 10 nm or others depending on the type of the coating material. The probe detects the pressure of acoustic and/or ultrasound waves propagating within an immersion medium, whenever the probe tip is immersed inside the medium, and having a reasonable immersion contact surface.

Abstract: The present invention details fabrication guidelines of integrated optoelectronic oscillators with frequency and phase stability, having higher frequency selectivity in a relatively small size (compared to the larger size of a higher order electrically realized RF filter), reduced temperature sensitivity, and minimized frequency drift. The integrated photonic components and RF oscillator may use Silicon photonics and microelectronic integration using CMOS and BiCMOS technology, eliminating the need for bulky and/or discrete optical and microwave components.

Abstract: Aspects of the disclosure relate generally to a circuit for sustaining an radio frequency (RF) modulated optical signal. The circuit may comprise a self injection locking component having a fiber optic delay line over which a portion of the optical signal propagates. The circuit may also comprise a self phase locked loop component having at least two fiber optic cables having different lengths and over which another portion of the optical signal propagates and a phase detector coupled to the at least two fiber optic cables and configured to determine a phase difference between the signals propagating over one of the respective fiber optic cables. The circuit may further comprise a voltage controlled oscillator configured to generate a stable oscillating signal in response to signals generated by each of the self injection locking and self phase locked loop components, the stable oscillating signal being configured to sustain the optical signal.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: Self-oscillating mixer circuits for use in communications systems. The circuits comprise a push-pull amplifier for amplifying a signal having a first frequency to produce an amplified signal, a feedback loop coupled to the push-pull amplifier for phase shifting the amplified signal during each half cycle of the push-pull amplifier, thereby creating an oscillating output signal, and a mixing element for coupling the oscillating output signal to the signal having the first frequency, thereby mixing the signal having the first frequency with the oscillating signal to produce a signal having a second frequency. The circuits described herein have transistors that operate near the class B mode to obtain optimal frequency conversion with minimal power consumption. These circuits will therefore find use in any communications-type system which requires a frequency converter.

Abstract: A fundamental or subharmonic optically injection locked oscillator is coupled to a phase locked loop circuit. The injection locked oscillator has two single stage HEMT amplifiers with parallel feedback from the drain of a second transistor to a gate of a first transistor. A feedback resonant network controls the oscillator frequency. A microwave/millimeter wave source modulates a laser diode and the signal from the laser diode is then transmitted via an optical fiber to a PIN photodetector diode. The signal from the photodetector diode is injected into the oscillator at an nth subharmonic of the oscillator frequency. The feedback network may consist of a microstrip gap resonator with two tuning varactors at the ends of the resonator. The phase locked loop includes a balanced mixer used as a phase detector to compare the nth harmonic of the signal from the photodetector diode to the sampled output of the oscillator.

Abstract: An optical transmitter particularly suited for high frequency applications s disclosed. The optical transmitter successfully operates in harsh environments such as those found in avionic applications. The optical transmitter employs an LED as a light source which cooperates with an active bandpass amplifier to provide a relatively wide bandwidth from about 250 MHz to about at least 1.35 GHz. The bandpass amplifier is selected to have a slope characteristic which is complementary to a roll-off characteristic of the LED and compensates for the high frequency loss of the LED. The slope characteristic of the bandpass amplifier predominates at the high frequencies of the response of the optical transmitter, whereas the frequency response of the LED dominates at the lower frequencies of the response.

Abstract: The characteristics of antennas are modified by photosensitive electrical elements connected to the radiating elements. The photosensitive elements are biased by light, by direct electrical bias, or both. The photosensitive element may be a PIN diode. The bias may be applied by general illumination or conducted by a fiber optic cable.