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Papers by Donald R. Lyons, Sr.

Optics Communications, Jul 1, 1981

Doppler-free optogalvanic spectra of two neon lines have been observed, with a radiofrequency osc... more Doppler-free optogalvanic spectra of two neon lines have been observed, with a radiofrequency oscillator used to both excite the discharge and detect the laser-induced change in ion density. Both intermodulated and polarization-intermodulated (POL1NEX) methods have been used. The sensitivity is similar to that obtained with fluorescence detection.

ABSTRACT The theoretical model we designed parameterizes the power losses as a function of .the p... more ABSTRACT The theoretical model we designed parameterizes the power losses as a function of .the profile shape for a tapered, single mode, optical dielectric coupler. The focus of this project is to produce a working model that determines the power losses experienced by the fibers when light crosses a taper region. This phenomenon can be examined using coupled mode theory. The optical directional coupler consists of a parallel, dual-channel, waveguide with minimal spacing between the channels to permit energy exchange. Thus, power transfer is essentially a function of the taper profile. To find the fields in the fibers, the approach used was that of solving the Helmholtz equation in cylindrical coordinates involving Bessel and modified Bessel functions depending on the location.

SPringer series in optical sciences, 1981

The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sen... more The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sensitivity by Polarization Intermodulated Excitation (POLINEX). We have demonstrated this technique with Doppler-free spectroscopy of excited helium and neon atoms in glow discharges, using optogalvanic or fluorescence detection. The neon spectra are free of Doppler-broadened background despite velocity changing elastic collisions.

Optics Communications, Jul 1, 1981

The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sen... more The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sensitivity by Polarization Intermodulated Excitation (POLINEX). We have demonstrated this technique with Doppler-free spectroscopy of excited helium and neon atoms in glow discharges, using optogalvanic or fluorescence detection. The neon spectra are free of Doppler-broadened background despite velocity changing elastic collisions.

ABSTRACT We present a scaled-down method for determining high temperatures using fiber-based Brag... more ABSTRACT We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.

NASA STI/Recon Technical Report N, 2003

A new device, establishing a wavelength standard for precise modulation spacing of transverse hol... more A new device, establishing a wavelength standard for precise modulation spacing of transverse holographic gratings, is reported. Each writing location and wavelength is calibrated against a known laser standard, allowing a precision approaching one part in one million

arXiv (Cornell University), Mar 31, 2002

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.

Applied optics, Nov 1, 2000

We present the preliminary results of a metrological standard for fiber Bragg gratings. This devi... more We present the preliminary results of a metrological standard for fiber Bragg gratings. This device is based on well-established wavemeter concepts and allows for the a priori determination of Bragg resonances that are verifiable and accurate. Although the concept is demonstrated here with small-fringe-number samplings, the production and detection of images of 50,000 metering fringes was easily accomplished with a nonidealized imaging system. Thus, since the system is characteristically similar to a standard wavemeter, increased fringe counts produce accurate frequency counter ratios for the determination of Bragg resonances, allowing for its application as a universal metering tool for many holographic systems.

A LabView-based computer interface for fiber-optic artificial nerves has been devised as a Master... more A LabView-based computer interface for fiber-optic artificial nerves has been devised as a Masters thesis project. This project involves the use of outputs from wavelength multiplexed optical fiber sensors (artificial nerves), which are capable of producing dense optical data outputs for physical measurements. The potential advantages of using optical fiber sensors for sensory function restoration is the fact that well defined WDM-modulated signals can be transmitted to and from the sensing region allowing networked units to replace low-level nerve functions for persons desirous of "intelligent artificial limbs." Various FO sensors can be designed with high sensitivity and the ability to be interfaced with a wide range of devices including miniature shielded electrical conversion units. Our Virtual Instrument (VI) interface software package was developed using LabView's "Laboratory Virtual Instrument Engineering Workbench" package. The virtual instrument has been configured to arrange and encode the data to develop an intelligent response in the form of encoded digitized signal outputs. The architectural layout of our nervous system is such that different touch stimuli from different artificial fiber-optic nerve points correspond to gratings of a distinct resonant wavelength and physical location along the optical fiber. Thus, when an automated, tunable diode laser sends scans, the wavelength spectrum of the artificial nerve, it triggers responses that are encoded with different touch stimuli by way wavelength shifts in the reflected Bragg resonances. The reflected light is detected and a resulting analog signal is fed into ADC1 board and DAQ card. Finally, the software has been written such that the experimenter is able to set the response range during data acquisition.

We present current results concerning novel sensor-based applications for tilted angle fiber Brag... more We present current results concerning novel sensor-based applications for tilted angle fiber Bragg gratings summarized in a recently filed patent. In addition, concepts involving the coupling of light out of the core region of an optical fiber using ablated corrugations to induce interactions with the surrounding media will also be discussed. The interactions between the media and the coupled light formulate the sensing mechanism for both of these devices. The research illustrated here is an extension of previous work that investigated the affects of intense UV radiation fields on both SiO2 and Ge-doped SiO2-based structures (specifically optical fibers and preforms). Finally, these sensors were devised in order to satisfy an experimental task set forth by NASA Glenn involving the production of a prototype evanescent field sensor capable of real-time, dynamic index of refraction measurements as well as early (ultra-high sensitivity) detection of icing on airplane wings.

Applied Optics, 1999

We present a simple, cost-effective method for creating diffractive optical elements on the surfa... more We present a simple, cost-effective method for creating diffractive optical elements on the surfaces of optical fibers and fiber-optic components by use of 193-nm ablation techniques. It is an outgrowth of a more fundamental investigation of the effects of intense UV radiation fields on SiO 2-and Ge-SiO 2-based structures ͑specifically optical fibers and preforms͒ and allows the inexpensive fabrication of structures such as the suggested evanescent-field-based sensing device.

Applied Optics, 2000

We report on an investigation of the trapezoidal design and fabrication defects in phase masks us... more We report on an investigation of the trapezoidal design and fabrication defects in phase masks used to produce Bragg reflection gratings in optical fibers. We used a direct visualization technique to examine the nonuniformity of the interference patterns generated by several phase masks. Fringe patterns from the phase masks are compared with the analogous patterns resulting from two-beam interference. Atomic force microscope imaging of the actual phase gratings that give rise to anomalous fringe patterns is used to determine input parameters for a general theoretical model. Phase masks with pitches of 0.566 and 1.059 m are modeled and investigated.

Applied Optics, 2000

We present the preliminary results of a metrological standard for fiber Bragg gratings. This devi... more We present the preliminary results of a metrological standard for fiber Bragg gratings. This device is based on well-established wavemeter concepts and allows for the a priori determination of Bragg resonances that are verifiable and accurate. Although the concept is demonstrated here with small-fringe-number samplings, the production and detection of images of 50,000 metering fringes was easily accomplished with a nonidealized imaging system. Thus, since the system is characteristically similar to a standard wavemeter, increased fringe counts produce accurate frequency counter ratios for the determination of Bragg resonances, allowing for its application as a universal metering tool for many holographic systems.

Eprint Arxiv Physics 0204005, Mar 1, 2002

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.

Optics Communications, Jul 1, 1981

Doppler-free optogalvanic spectra of two neon lines have been observed, with a radiofrequency osc... more Doppler-free optogalvanic spectra of two neon lines have been observed, with a radiofrequency oscillator used to both excite the discharge and detect the laser-induced change in ion density. Both intermodulated and polarization-intermodulated (POL1NEX) methods have been used. The sensitivity is similar to that obtained with fluorescence detection.

ABSTRACT The theoretical model we designed parameterizes the power losses as a function of .the p... more ABSTRACT The theoretical model we designed parameterizes the power losses as a function of .the profile shape for a tapered, single mode, optical dielectric coupler. The focus of this project is to produce a working model that determines the power losses experienced by the fibers when light crosses a taper region. This phenomenon can be examined using coupled mode theory. The optical directional coupler consists of a parallel, dual-channel, waveguide with minimal spacing between the channels to permit energy exchange. Thus, power transfer is essentially a function of the taper profile. To find the fields in the fibers, the approach used was that of solving the Helmholtz equation in cylindrical coordinates involving Bessel and modified Bessel functions depending on the location.

SPringer series in optical sciences, 1981

The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sen... more The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sensitivity by Polarization Intermodulated Excitation (POLINEX). We have demonstrated this technique with Doppler-free spectroscopy of excited helium and neon atoms in glow discharges, using optogalvanic or fluorescence detection. The neon spectra are free of Doppler-broadened background despite velocity changing elastic collisions.

Optics Communications, Jul 1, 1981

The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sen... more The nonlinear interaction of two laser beams in an absorbing medium can be detected with high sensitivity by Polarization Intermodulated Excitation (POLINEX). We have demonstrated this technique with Doppler-free spectroscopy of excited helium and neon atoms in glow discharges, using optogalvanic or fluorescence detection. The neon spectra are free of Doppler-broadened background despite velocity changing elastic collisions.

ABSTRACT We present a scaled-down method for determining high temperatures using fiber-based Brag... more ABSTRACT We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.

NASA STI/Recon Technical Report N, 2003

A new device, establishing a wavelength standard for precise modulation spacing of transverse hol... more A new device, establishing a wavelength standard for precise modulation spacing of transverse holographic gratings, is reported. Each writing location and wavelength is calibrated against a known laser standard, allowing a precision approaching one part in one million

arXiv (Cornell University), Mar 31, 2002

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.

Applied optics, Nov 1, 2000

We present the preliminary results of a metrological standard for fiber Bragg gratings. This devi... more We present the preliminary results of a metrological standard for fiber Bragg gratings. This device is based on well-established wavemeter concepts and allows for the a priori determination of Bragg resonances that are verifiable and accurate. Although the concept is demonstrated here with small-fringe-number samplings, the production and detection of images of 50,000 metering fringes was easily accomplished with a nonidealized imaging system. Thus, since the system is characteristically similar to a standard wavemeter, increased fringe counts produce accurate frequency counter ratios for the determination of Bragg resonances, allowing for its application as a universal metering tool for many holographic systems.

A LabView-based computer interface for fiber-optic artificial nerves has been devised as a Master... more A LabView-based computer interface for fiber-optic artificial nerves has been devised as a Masters thesis project. This project involves the use of outputs from wavelength multiplexed optical fiber sensors (artificial nerves), which are capable of producing dense optical data outputs for physical measurements. The potential advantages of using optical fiber sensors for sensory function restoration is the fact that well defined WDM-modulated signals can be transmitted to and from the sensing region allowing networked units to replace low-level nerve functions for persons desirous of "intelligent artificial limbs." Various FO sensors can be designed with high sensitivity and the ability to be interfaced with a wide range of devices including miniature shielded electrical conversion units. Our Virtual Instrument (VI) interface software package was developed using LabView's "Laboratory Virtual Instrument Engineering Workbench" package. The virtual instrument has been configured to arrange and encode the data to develop an intelligent response in the form of encoded digitized signal outputs. The architectural layout of our nervous system is such that different touch stimuli from different artificial fiber-optic nerve points correspond to gratings of a distinct resonant wavelength and physical location along the optical fiber. Thus, when an automated, tunable diode laser sends scans, the wavelength spectrum of the artificial nerve, it triggers responses that are encoded with different touch stimuli by way wavelength shifts in the reflected Bragg resonances. The reflected light is detected and a resulting analog signal is fed into ADC1 board and DAQ card. Finally, the software has been written such that the experimenter is able to set the response range during data acquisition.

We present current results concerning novel sensor-based applications for tilted angle fiber Brag... more We present current results concerning novel sensor-based applications for tilted angle fiber Bragg gratings summarized in a recently filed patent. In addition, concepts involving the coupling of light out of the core region of an optical fiber using ablated corrugations to induce interactions with the surrounding media will also be discussed. The interactions between the media and the coupled light formulate the sensing mechanism for both of these devices. The research illustrated here is an extension of previous work that investigated the affects of intense UV radiation fields on both SiO2 and Ge-doped SiO2-based structures (specifically optical fibers and preforms). Finally, these sensors were devised in order to satisfy an experimental task set forth by NASA Glenn involving the production of a prototype evanescent field sensor capable of real-time, dynamic index of refraction measurements as well as early (ultra-high sensitivity) detection of icing on airplane wings.

Applied Optics, 1999

We present a simple, cost-effective method for creating diffractive optical elements on the surfa... more We present a simple, cost-effective method for creating diffractive optical elements on the surfaces of optical fibers and fiber-optic components by use of 193-nm ablation techniques. It is an outgrowth of a more fundamental investigation of the effects of intense UV radiation fields on SiO 2-and Ge-SiO 2-based structures ͑specifically optical fibers and preforms͒ and allows the inexpensive fabrication of structures such as the suggested evanescent-field-based sensing device.

Applied Optics, 2000

We report on an investigation of the trapezoidal design and fabrication defects in phase masks us... more We report on an investigation of the trapezoidal design and fabrication defects in phase masks used to produce Bragg reflection gratings in optical fibers. We used a direct visualization technique to examine the nonuniformity of the interference patterns generated by several phase masks. Fringe patterns from the phase masks are compared with the analogous patterns resulting from two-beam interference. Atomic force microscope imaging of the actual phase gratings that give rise to anomalous fringe patterns is used to determine input parameters for a general theoretical model. Phase masks with pitches of 0.566 and 1.059 m are modeled and investigated.

Applied Optics, 2000

We present the preliminary results of a metrological standard for fiber Bragg gratings. This devi... more We present the preliminary results of a metrological standard for fiber Bragg gratings. This device is based on well-established wavemeter concepts and allows for the a priori determination of Bragg resonances that are verifiable and accurate. Although the concept is demonstrated here with small-fringe-number samplings, the production and detection of images of 50,000 metering fringes was easily accomplished with a nonidealized imaging system. Thus, since the system is characteristically similar to a standard wavemeter, increased fringe counts produce accurate frequency counter ratios for the determination of Bragg resonances, allowing for its application as a universal metering tool for many holographic systems.

Eprint Arxiv Physics 0204005, Mar 1, 2002

We present an approximate analytic model that has been developed for examining hydrodynamic flow ... more We present an approximate analytic model that has been developed for examining hydrodynamic flow near the surface of a fiber optic sensor. An analysis of the conservation of momentum, the continuity equation and the Navier-Stokes equation for compressible flow was used to develop expressions for the velocity & v and the density ρ as a function of the distance along the flow and above a two dimensional flat surface. When examining the flow near the surface, these expressions can be used to estimate the sensitivity required to perform direct optical measurements and to parameterize the shear force for indirect optical measurements. The use of these results allows for direct modeling of sensors using the optical properties of the flow field. Future work includes analyzing the optical parametric design of fiber optic sensors, modeling sensors to utilize those parameters for optimal measurements involving different mixtures of fluid flow.