Abstract: A pulse transformer for modifying the amplitude and phase of short optical pulses includes a pulse source and an adaptively controlled stretcher or compressor including at least one fiber Bragg grating (FBG) configured to receive pulses from the pulse source and having a first second-order dispersion parameter (D21). The pulse transformer further includes at least one optical amplifier configured to receive pulses from the FBG and a compressor configured to receive pulses from the at least one optical amplifier. The compressor has a second second-order dispersion parameter (?D22), an absolute value of the first second-order dispersion parameter (|D21|) and an absolute value of the second second-order dispersion parameter (|?D22|) that are substantially equal to one another to within 10%.

Abstract: Example ultra narrow linewidth Brillouin lasers are disclosed that are pumped by pump lasers that are controlled via optimal control schemes in order to stabilize the Brillouin laser output frequency and minimize the Brillouin output linewidth. The control schemes are based on feedback loops to match the pump laser frequency to the optimum Stokes shift on the one hand and to line-narrow the pump laser linewidth on the other hand via comparing the linewidth of the pump laser with the linewidth of the Brillouin laser. The feedback loops in the control schemes can be partially or fully replaced with feedforward control schemes, allowing for larger bandwidth control. Provision for simultaneous oscillation of the Brillouin lasers on two polarization modes allows for further line-narrowing of the Brillouin output.

Abstract: Systems and methods for precision control of microresonator (MR) based frequency combs can implement optimized MR actuators or MR modulators to control long-term locking of carrier envelope offset frequency, repetition rate, or resonance offset frequency of the MR. MR modulators can also be used for amplitude noise control. MR parameters can be locked to external reference frequencies such as a continuous wave laser or a microwave reference. MR parameters can be selected to reduce cross talk between the MR parameters, facilitating long-term locking. The MR can be locked to an external two wavelength delayed self-heterodyne interferometer for low noise microwave generation. An MR-based frequency comb can be tuned by a substantial fraction or more of the free spectral range (FSR) via a feedback control system. Scanning MR frequency combs can be applied to dead-zone free spectroscopy, multi-wavelength LIDAR, high precision optical clocks, or low phase noise microwave sources.

Abstract: Systems and methods for precision control of microresonator (MR) based frequency combs can implement optimized MR actuators or MR modulators to control long-term locking of carrier envelope offset frequency, repetition rate, or resonance offset frequency of the MR. MR modulators can also be used for amplitude noise control. MR parameters can be locked to external reference frequencies such as a continuous wave laser or a microwave reference. MR parameters can be selected to reduce cross talk between the MR parameters, facilitating long-term locking. The MR can be locked to an external two wavelength delayed self-heterodyne interferometer for low noise microwave generation. An MR-based frequency comb can be tuned by a substantial fraction or more of the free spectral range (FSR) via a feedback control system. Scanning MR frequency combs can be applied to dead-zone free spectroscopy, multi-wavelength LIDAR, high precision optical clocks, or low phase noise microwave sources.

Abstract: In an example amplifier system, an input pulse train is passed through an optical stage that splits each pulse into two or more pulses. These divided pulses are then injected into at least two amplifiers for amplification. The amplified pulses are subsequently passed back through the same optical stage in order to combine the pulses back into one high energy pulse. The amplifier system can use time division multiplexing (TDM) and/or spatial division multiplexing (SDM) to produce, e.g., four pulses in conjunction with two amplifiers and propagation through two optical beam splitters, which are coherently combined into a single output pulse after amplification. The amplifiers can comprise fiber amplifiers or bulk amplifiers.

Abstract: Examples of systems and methods for integrated photonic broadband microwave receivers and transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a receiver, the microwave spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can be coherently added or encoded independently for transmission of individual microwave bands. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example, based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

Abstract: A pulse transformer for modifying the amplitude and phase of short optical pulses includes a pulse source and an adaptively controlled stretcher or compressor including at least one fiber Bragg grating (FBG) configured to receive pulses from the pulse source and having a first second-order dispersion parameter (D21). The pulse transformer further includes at least one optical amplifier configured to receive pulses from the FBG and a compressor configured to receive pulses from the at least one optical amplifier. The compressor has a second second-order dispersion parameter (?D22), an absolute value of the first second-order dispersion parameter (|D21|) and an absolute value of the second second-order dispersion parameter (|?D22|) that are substantially equal to one another to within 10%.

Abstract: Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

Abstract: Systems and methods for stabilizing mid-infrared light generated by difference frequency mixing may include a mode locked Er fiber laser that generates pulses, which are split into a pump arm and a wavelength shifting, signal arm. Pump arm pulses are amplified in Er doped fiber. Shifting arm pulses are amplified in Er doped fiber and shifted to longer wavelengths in Raman-shifting fiber or highly nonlinear fiber, where they may be further amplified by Tm doped fiber, and then optionally further wavelength shifted. Pulses from the two arms can be combined in a nonlinear crystal such as orientation-patterned gallium phosphide, producing a mid-infrared difference frequency, as well as nonlinear combinations (e.g., sum frequency) having near infrared and visible wavelengths. Optical power stabilization can be achieved using two wavelength ranges with spectral filtering and multiple detectors acquiring information for feedback control. Controlled fiber bending can be used to stabilize optical power.

Abstract: Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

Abstract: Examples of systems and methods for integrated photonic broadband microwave transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can either be encoded independently, or used for broadcasting the same information into different bands. In some cases, when the system is configured as a receiver, the spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

Abstract: Low phase noise radio frequency (RF) sources generated by voltage controlled oscillators (VCOs) are described. Optical modulators driven by a VCO may be used to generate optical side-bands to cw lasers. The spectral extent of said side-bands can be increased via frequency broadening in highly nonlinear waveguides. Free running mode locked low phase noise comb oscillators can be used as reference oscillators to generate beat signals between those side-bands and individual comb modes at distal spectral regions, thereby creating an error signal used to reduce the phase noise of VCOs and the generation of low phase noise RF signals. VCO phase noise may be reduced by using free-running modelocked comb lasers phase locked to external frequency references, by omitting a reference comb and using a nonlinear interferometer for generating an error signal, or by locking a slave comb to the modulation frequency of an intra-cavity modulator driven by the VCO.

Abstract: In an example amplifier system, an input pulse train is passed through an optical stage that splits each pulse into two or more pulses. These divided pulses are then injected into at least two amplifiers for amplification. The amplified pulses are subsequently passed back through the same optical stage in order to combine the pulses back into one high energy pulse. The amplifier system can use time division multiplexing (TDM) and/or spatial division multiplexing (SDM) to produce, e.g., four pulses in conjunction with two amplifiers and propagation through two optical beam splitters, which are coherently combined into a single output pulse after amplification. The amplifiers can comprise fiber amplifiers or bulk amplifiers.

Abstract: The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

Abstract: Systems and methods for stabilizing mid-infrared light generated by difference frequency mixing may include a mode locked Er fiber laser that generates pulses, which are split into a pump arm and a wavelength shifting, signal arm. Pump arm pulses are amplified in Er doped fiber. Shifting arm pulses are amplified in Er doped fiber and shifted to longer wavelengths in Raman-shifting fiber or highly nonlinear fiber, where they may be further amplified by Tm doped fiber, and then optionally further wavelength shifted. Pulses from the two arms can be combined in a nonlinear crystal such as orientation-patterned gallium phosphide, producing a mid-infrared difference frequency, as well as nonlinear combinations (e.g., sum frequency) having near infrared and visible wavelengths. Optical power stabilization can be achieved using two wavelength ranges with spectral filtering and multiple detectors acquiring information for feedback control. Controlled fiber bending can be used to stabilize optical power.

Abstract: Examples of systems and methods for integrated photonic broadband microwave transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can either be encoded independently, or used for broadcasting the same information into different bands. In some cases, when the system is configured as a receiver, the spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

Abstract: By compensating polarization mode-dispersion as well chromatic dispersion in photonic crystal fiber pulse compressors, high pulse energies can be obtained from all-fiber chirped pulse amplification systems. By inducing third-order dispersion in fiber amplifiers via self-phase modulation, the third-order chromatic dispersion from bulk grating pulse compressors can be compensated and the pulse quality of hybrid fiber/bulk chirped pulse amplification systems can be improved. Finally, by amplifying positively chirped pulses in negative dispersion fiber amplifiers, a low noise wavelength tunable seed source via anti-Stokes frequency shifting can be obtained.

Abstract: Various embodiments include large cores fibers that can propagate few modes or a single mode while introducing loss to higher order modes. Some of these fibers are holey fibers that comprise cladding features such as air-holes. Additional embodiments described herein include holey rods. The rods and fibers may be used in many optical systems including optical amplification systems, lasers, short pulse generators, Q-switched lasers, etc. and may be used for example for micromachining.

Abstract: This disclosure relates to polarizing optical fibers and polarization maintaining optical fibers, including active and/or passive implementations. An embodiment includes a polarizing (PZ) optical fiber that includes stress applying parts (SAPs) disposed in a first cladding region, the SAPs comprising a material with a thermal expansion coefficient, ?SAP. A core region is at least partially surrounded by cladding features and the SAPs. The core includes glass with a thermal expansion coefficient, ?core. The arrangement of the SAPs satisfies: Rsc=dSAP/Dsc, where Dsc is the SAP center to core center distance, and dSAP is the average SAP diameter, and d?=|?SAP??core|, and where Rsc and d? may be sufficiently large to induce stress birefringence into the core and to provide for polarized output. Active fibers in which a portion of the fiber is doped may be implemented for application in fiber lasers, fiber amplifiers, and/or optical pulse compressors.

Abstract: Systems and methods for precision phase noise measurements of radio frequency (RF) oscillators are provided. An RF signal under test can be modulated on a continuous wave (cw) laser carrier frequency via generation of modulation sidebands using an appropriate modulator. A photonic delay line can be implemented as a self-heterodyne detection system for the phase noise, allowing for photonic down-conversion of the phase noise measurement to direct current (DC). The self-heterodyne detection system allows detection outside of any 1/f noise issues. Ultra-low phase noise detection for RF frequencies in a range from below 1 GHz to beyond 100 GHz is enabled with a low noise floor in the whole frequency range. Higher-order modulation sidebands can further reduce the noise floor of the system. Ultra-low noise RF (microwave) output can be generated. The RF signal under test can be generated by a dielectric resonance oscillator or opto-electronic oscillator.