A. Boh Ruffin - Academia.edu (original) (raw)

Papers by A. Boh Ruffin

Optics Express, 2007

We propose a novel approach of making large effective area laser fiber with higher threshold for ... more We propose a novel approach of making large effective area laser fiber with higher threshold for the stimulated Brillouin scattering (SBS) using Al/Ge co-doping in the fiber core. The increased SBS threshold is achieved by reducing the acoustic-optic overlap integral while keeping the optical refractive index profile with a step structure. The manipulation of the overlap integral is done by adjusting the relative doping level between Al 2 O 3 and GeO 2 in the core. The mechanism is validated by detailed examples of numerical modeling. An Yb-doped double clad fiber with the core co-doped with Al 2 O 3 and GeO 2 was fabricated by the OVD process. Measured acoustic velocity profile using a scanning acoustic microscope verified that the acoustic velocity in the fiber core changes with the design. An amplifier utilizing the fiber demonstrated that the proposed fiber yielded 6 dB higher SBS threshold than a fiber without using the co-doping scheme.

Typically, the inverse problem has employed frequency domain techniques to reconstruct an object ... more Typically, the inverse problem has employed frequency domain techniques to reconstruct an object from directly measured scattered fields. Recently, time-domain approaches to the inverse problem have been demonstrated using both electromagnetic and acoustic pulses. More recently, we developed another time-domain imaging technique in which diffracted transients from amplitude-contrast (metallic) objects were used to reconstruct their spatial transmission functions. In a

The purpose of this research was to develop an optical method of leak detection. Various modifica... more The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

IEEE Journal of Selected Topics in Quantum Electronics, 2009

In this paper, we discuss the design of optical fibers with tailored acoustic speed profiles to s... more In this paper, we discuss the design of optical fibers with tailored acoustic speed profiles to suppress stimulated Brillouin scattering in high-power, single-frequency sources. We demonstrate the ability of these fibers to achieve single-mode output powers of greater than 500 W and discuss the potential to achieve powers beyond 1 kW.

We demonstrate the advantages of passive stimulated Brillouin scattering (SBS) mitigation enabled... more We demonstrate the advantages of passive stimulated Brillouin scattering (SBS) mitigation enabled through fiber design. We compare the system performance of a radio-over-fiber (ROF) link using a standard ITU G.652.D fiber (Corning® SMF28e® fiber) and a second ITU G.652.D fiber with a 3-dB higher SBS threshold (Corning® NexCor® fiber). Experimental results demonstrate a significant reduction in SBS induced signal distortions and improvements in optical link reach. Our fiber-based SBS mitigation provides a cost effective means to implement high-powered, extended reach ROF networks.

2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006

... 0 10 20 30 40 50 60 Core Diameter (μm) E ffec tiv e A rea ( μm 2 ) NA=0.05 NA=0.08 NA=0.12 ..... more ... 0 10 20 30 40 50 60 Core Diameter (μm) E ffec tiv e A rea ( μm 2 ) NA=0.05 NA=0.08 NA=0.12 ... 631-639, 2004. 6. A. Boh Ruffin, MJLi, X. Chen, A. Kobyakov, and F. Annunziata, “Brillouin Gain Analysis for Fibers with Different Refractive Indices”, Accepted for publication in Opt. ...

32nd Joint Propulsion Conference and Exhibit, 1996

Electronics Letters, 1995

Stimulated Brillouin scattering (SBS) in a fiber is suppressed by making the core radius nonunifo... more Stimulated Brillouin scattering (SBS) in a fiber is suppressed by making the core radius nonuniform along its length to utilise the core-radius dependence of the longitudinal acoustic frequency. The effective Brillouin gain of an SBS suppression fiber prepared by the VAD method was reduced by 3.5dB compared with conventional fibers.

Technical Digest: Symposium on Optical Fiber Measurements, 2004.

Basic concepts of stimulated Brillouin scattering are reviewed together with Brillouin gain spect... more Basic concepts of stimulated Brillouin scattering are reviewed together with Brillouin gain spectrum characterization techniques, system impairments, and applications.

Ultrafast Electronics and Optoelectronics, 2001

ABSTRACT © 2001 Optical Society of America

2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006

ABSTRACT We propose a new and efficient approach to generation of a continuous-wave supercontinuu... more ABSTRACT We propose a new and efficient approach to generation of a continuous-wave supercontinuum in optical fiber pumped by an amplified spontaneous emission light. A bandwidth of 268 nm (at -15 dB level) with an average spectral density of 2.7 mW/nm is demonstrated

Optical Amplifiers and Their Applications/Coherent Optical Technologies and Applications, 2006

ABSTRACT Amplification of narrow linewidth signals in optical fibers is limited by stimulated Bri... more ABSTRACT Amplification of narrow linewidth signals in optical fibers is limited by stimulated Brillouin scattering (SBS). We discuss novel fiber designs that limit SBS allowing the amplification of narrow linewidth signals to kilowatt power levels.

SPIE Proceedings, 2002

ABSTRACT The design of optical communication networks with network switching elements operating i... more ABSTRACT The design of optical communication networks with network switching elements operating in the optical domain requires careful system analysis and potentially stringent component requirements. We consider here network elements such as transparent optical cross-connects that demultiplex WDM signals, optically switch individual channels, and then multiplex the wavelengths together again before transmission into the next span. Network element optical impairments that can degrade signal quality are in-band (same wavelength) crosstalk, out-of-band crosstalk, and signal distortion from filter concatenation effects. These impairments can limit the transmission distance of a signal before regeneration is required. We examine the trade-offs between crosstalk and filter distortion in the context of the optical filters used in the optical multiplexers and demultiplexers in the network elements. We demonstrate the balance that must be struck between these impairment types in the design of the filters and network system. We study a 10 Gb/s network with 50 GHz channel spacing, examining both NRZ and RZ modulation formats. In both cases, we find optimal filter bandwidths that minimize the total signal degradation measured in terms of Q penalty. The total penalty suffered by RZ signals is higher than that of NRZ signals and must be considered when estimating system reach.

SPIE Proceedings, 2007

ABSTRACT In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by ... more ABSTRACT In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by different light sources which include fs and ps pulse sources, and continuous-wave (CW) amplified spontaneous emission (ASE) light sources. First, we demonstrated SC generation with a 10dB spectral bandwidth of 430nm in a fiber ring laser with conventional nonlinear fiber. Second, we proposed and demonstrated a new and efficient approach to generation of a CW SC in optical fibers pumped by a CW ASE light. A bandwidth of 268nm (at -15dB level) with an average spectral density of 2.7mW/nm was demonstrated. Various approaches to flattening the spectrum and increasing the spectral width were also studied. The application of this SC source in WDM passive optical access networks (WDM-PONs) was investigated. Third, the approach of SC generation in a fiber combination of standard SMF and nonlinear DSF pumped by an all-fiber fs pulse Master Oscillator Power Amplifier (MOPA) system was developed. A spectral bandwidth of over 1000nm was demonstrated. Finally, the generation of broad comb-like-spectral light based on the pulse compression of 40GHz optical pulses in a new nonlinear dispersion-decreasing fiber with high SBS threshold was studied. A continuum light source with over 125 channels and a channel spacing of 40 GHz was achieved. The use of this continuum light source as WDM source in WDM-PONs was investigated.

National Fiber Optic Engineers Conference, 2010

Consumer expectations for high quality high-definition programming will place greater demand on a... more Consumer expectations for high quality high-definition programming will place greater demand on access networks as flat-panel display sizes increase. Herein, we investigate the bandwidth requirement to deliver high quality HD viewing experience for larger displays.

Optics Letters, 2005

We studied an anomalous result in the measured stimulated Brillouin scattering threshold for sing... more We studied an anomalous result in the measured stimulated Brillouin scattering threshold for single-mode optical fibers with different refractive index profiles and effective areas. It was found that, in addition to the optical effective area, the refractive-index-dependent interaction between the optical and the acoustic fields must be considered in order to account for the differences in the stimulated Brillouin scattering threshold between fiber types. A detailed analytical formalism describing the acousto-optic interaction was derived to accommodate the influence of the index profile design on Brillouin scattering.

Optics Letters, 2001

We demonstrate the reconstruction of one-and two-dimensional objects by numerically backpropagati... more We demonstrate the reconstruction of one-and two-dimensional objects by numerically backpropagating measured scattered terahertz transients. The spatial resolution determined by the Sparrow criterion is found to correspond to approximately 30% of the peak wavelength and 85% of the mean wavelength of the power spectrum of the single-cycle waveform.

Optics Express, 2005

We propose a criterion to predict the relative value of the stimulated Brillouin scattering (SBS)... more We propose a criterion to predict the relative value of the stimulated Brillouin scattering (SBS) threshold in single-mode optical fibers with different refractive index profiles. We confirm our results by several representative measurements. We show that with the proper profile design one can achieve more than 3 dB increase in the SBS threshold compared to the standard single-mode optical fiber.

Journal of Lightwave Technology, 2006

After more than 20 years of research and development, a combination of technological, regulatory,... more After more than 20 years of research and development, a combination of technological, regulatory, and competitive forces are finally bringing fiber-based broadband access to commercial fruition. The three main approaches-hybrid fiber coax, fiber to the cabinet, and fiber to the home-are each vying for dominance in the industry, and each has significant future potential to grow customers and increase bandwidth and associatedservice offerings. Further technical advances and cost reductions will be adopted, eventually bringing performance levels and bandwidth to gigabits-per-second rates when user demand warrants while keeping service costs affordable. Index Terms-Access networks, broadband access, digital subscriber line, fiber to the cabinet, fiber to the home, full service access network, hybrid fiber coax, passive optical network.

IEEE Photonics Technology Letters, 2007

We show that impairments related to stimulated Brillouin scattering in radio-over-fiber transmiss... more We show that impairments related to stimulated Brillouin scattering in radio-over-fiber transmission can be strongly suppressed with the proper choice of a segmented single-mode optical fiber. As a result, low error vector magnitude (EVM) can be achieved for remote antenna feeding of IEEE 802.11a/g wireless LAN signals, resulting in 1% EVM degradation after 20-km transmission at 14 dBm.

Optics Express, 2007

We propose a novel approach of making large effective area laser fiber with higher threshold for ... more We propose a novel approach of making large effective area laser fiber with higher threshold for the stimulated Brillouin scattering (SBS) using Al/Ge co-doping in the fiber core. The increased SBS threshold is achieved by reducing the acoustic-optic overlap integral while keeping the optical refractive index profile with a step structure. The manipulation of the overlap integral is done by adjusting the relative doping level between Al 2 O 3 and GeO 2 in the core. The mechanism is validated by detailed examples of numerical modeling. An Yb-doped double clad fiber with the core co-doped with Al 2 O 3 and GeO 2 was fabricated by the OVD process. Measured acoustic velocity profile using a scanning acoustic microscope verified that the acoustic velocity in the fiber core changes with the design. An amplifier utilizing the fiber demonstrated that the proposed fiber yielded 6 dB higher SBS threshold than a fiber without using the co-doping scheme.

Typically, the inverse problem has employed frequency domain techniques to reconstruct an object ... more Typically, the inverse problem has employed frequency domain techniques to reconstruct an object from directly measured scattered fields. Recently, time-domain approaches to the inverse problem have been demonstrated using both electromagnetic and acoustic pulses. More recently, we developed another time-domain imaging technique in which diffracted transients from amplitude-contrast (metallic) objects were used to reconstruct their spatial transmission functions. In a

The purpose of this research was to develop an optical method of leak detection. Various modifica... more The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

IEEE Journal of Selected Topics in Quantum Electronics, 2009

In this paper, we discuss the design of optical fibers with tailored acoustic speed profiles to s... more In this paper, we discuss the design of optical fibers with tailored acoustic speed profiles to suppress stimulated Brillouin scattering in high-power, single-frequency sources. We demonstrate the ability of these fibers to achieve single-mode output powers of greater than 500 W and discuss the potential to achieve powers beyond 1 kW.

We demonstrate the advantages of passive stimulated Brillouin scattering (SBS) mitigation enabled... more We demonstrate the advantages of passive stimulated Brillouin scattering (SBS) mitigation enabled through fiber design. We compare the system performance of a radio-over-fiber (ROF) link using a standard ITU G.652.D fiber (Corning® SMF28e® fiber) and a second ITU G.652.D fiber with a 3-dB higher SBS threshold (Corning® NexCor® fiber). Experimental results demonstrate a significant reduction in SBS induced signal distortions and improvements in optical link reach. Our fiber-based SBS mitigation provides a cost effective means to implement high-powered, extended reach ROF networks.

2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006

... 0 10 20 30 40 50 60 Core Diameter (μm) E ffec tiv e A rea ( μm 2 ) NA=0.05 NA=0.08 NA=0.12 ..... more ... 0 10 20 30 40 50 60 Core Diameter (μm) E ffec tiv e A rea ( μm 2 ) NA=0.05 NA=0.08 NA=0.12 ... 631-639, 2004. 6. A. Boh Ruffin, MJLi, X. Chen, A. Kobyakov, and F. Annunziata, “Brillouin Gain Analysis for Fibers with Different Refractive Indices”, Accepted for publication in Opt. ...

32nd Joint Propulsion Conference and Exhibit, 1996

Electronics Letters, 1995

Stimulated Brillouin scattering (SBS) in a fiber is suppressed by making the core radius nonunifo... more Stimulated Brillouin scattering (SBS) in a fiber is suppressed by making the core radius nonuniform along its length to utilise the core-radius dependence of the longitudinal acoustic frequency. The effective Brillouin gain of an SBS suppression fiber prepared by the VAD method was reduced by 3.5dB compared with conventional fibers.

Technical Digest: Symposium on Optical Fiber Measurements, 2004.

Basic concepts of stimulated Brillouin scattering are reviewed together with Brillouin gain spect... more Basic concepts of stimulated Brillouin scattering are reviewed together with Brillouin gain spectrum characterization techniques, system impairments, and applications.

Ultrafast Electronics and Optoelectronics, 2001

ABSTRACT © 2001 Optical Society of America

2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006

ABSTRACT We propose a new and efficient approach to generation of a continuous-wave supercontinuu... more ABSTRACT We propose a new and efficient approach to generation of a continuous-wave supercontinuum in optical fiber pumped by an amplified spontaneous emission light. A bandwidth of 268 nm (at -15 dB level) with an average spectral density of 2.7 mW/nm is demonstrated

Optical Amplifiers and Their Applications/Coherent Optical Technologies and Applications, 2006

ABSTRACT Amplification of narrow linewidth signals in optical fibers is limited by stimulated Bri... more ABSTRACT Amplification of narrow linewidth signals in optical fibers is limited by stimulated Brillouin scattering (SBS). We discuss novel fiber designs that limit SBS allowing the amplification of narrow linewidth signals to kilowatt power levels.

SPIE Proceedings, 2002

ABSTRACT The design of optical communication networks with network switching elements operating i... more ABSTRACT The design of optical communication networks with network switching elements operating in the optical domain requires careful system analysis and potentially stringent component requirements. We consider here network elements such as transparent optical cross-connects that demultiplex WDM signals, optically switch individual channels, and then multiplex the wavelengths together again before transmission into the next span. Network element optical impairments that can degrade signal quality are in-band (same wavelength) crosstalk, out-of-band crosstalk, and signal distortion from filter concatenation effects. These impairments can limit the transmission distance of a signal before regeneration is required. We examine the trade-offs between crosstalk and filter distortion in the context of the optical filters used in the optical multiplexers and demultiplexers in the network elements. We demonstrate the balance that must be struck between these impairment types in the design of the filters and network system. We study a 10 Gb/s network with 50 GHz channel spacing, examining both NRZ and RZ modulation formats. In both cases, we find optimal filter bandwidths that minimize the total signal degradation measured in terms of Q penalty. The total penalty suffered by RZ signals is higher than that of NRZ signals and must be considered when estimating system reach.

SPIE Proceedings, 2007

ABSTRACT In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by ... more ABSTRACT In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by different light sources which include fs and ps pulse sources, and continuous-wave (CW) amplified spontaneous emission (ASE) light sources. First, we demonstrated SC generation with a 10dB spectral bandwidth of 430nm in a fiber ring laser with conventional nonlinear fiber. Second, we proposed and demonstrated a new and efficient approach to generation of a CW SC in optical fibers pumped by a CW ASE light. A bandwidth of 268nm (at -15dB level) with an average spectral density of 2.7mW/nm was demonstrated. Various approaches to flattening the spectrum and increasing the spectral width were also studied. The application of this SC source in WDM passive optical access networks (WDM-PONs) was investigated. Third, the approach of SC generation in a fiber combination of standard SMF and nonlinear DSF pumped by an all-fiber fs pulse Master Oscillator Power Amplifier (MOPA) system was developed. A spectral bandwidth of over 1000nm was demonstrated. Finally, the generation of broad comb-like-spectral light based on the pulse compression of 40GHz optical pulses in a new nonlinear dispersion-decreasing fiber with high SBS threshold was studied. A continuum light source with over 125 channels and a channel spacing of 40 GHz was achieved. The use of this continuum light source as WDM source in WDM-PONs was investigated.

National Fiber Optic Engineers Conference, 2010

Consumer expectations for high quality high-definition programming will place greater demand on a... more Consumer expectations for high quality high-definition programming will place greater demand on access networks as flat-panel display sizes increase. Herein, we investigate the bandwidth requirement to deliver high quality HD viewing experience for larger displays.

Optics Letters, 2005

We studied an anomalous result in the measured stimulated Brillouin scattering threshold for sing... more We studied an anomalous result in the measured stimulated Brillouin scattering threshold for single-mode optical fibers with different refractive index profiles and effective areas. It was found that, in addition to the optical effective area, the refractive-index-dependent interaction between the optical and the acoustic fields must be considered in order to account for the differences in the stimulated Brillouin scattering threshold between fiber types. A detailed analytical formalism describing the acousto-optic interaction was derived to accommodate the influence of the index profile design on Brillouin scattering.

Optics Letters, 2001

We demonstrate the reconstruction of one-and two-dimensional objects by numerically backpropagati... more We demonstrate the reconstruction of one-and two-dimensional objects by numerically backpropagating measured scattered terahertz transients. The spatial resolution determined by the Sparrow criterion is found to correspond to approximately 30% of the peak wavelength and 85% of the mean wavelength of the power spectrum of the single-cycle waveform.

Optics Express, 2005

We propose a criterion to predict the relative value of the stimulated Brillouin scattering (SBS)... more We propose a criterion to predict the relative value of the stimulated Brillouin scattering (SBS) threshold in single-mode optical fibers with different refractive index profiles. We confirm our results by several representative measurements. We show that with the proper profile design one can achieve more than 3 dB increase in the SBS threshold compared to the standard single-mode optical fiber.

Journal of Lightwave Technology, 2006

After more than 20 years of research and development, a combination of technological, regulatory,... more After more than 20 years of research and development, a combination of technological, regulatory, and competitive forces are finally bringing fiber-based broadband access to commercial fruition. The three main approaches-hybrid fiber coax, fiber to the cabinet, and fiber to the home-are each vying for dominance in the industry, and each has significant future potential to grow customers and increase bandwidth and associatedservice offerings. Further technical advances and cost reductions will be adopted, eventually bringing performance levels and bandwidth to gigabits-per-second rates when user demand warrants while keeping service costs affordable. Index Terms-Access networks, broadband access, digital subscriber line, fiber to the cabinet, fiber to the home, full service access network, hybrid fiber coax, passive optical network.

IEEE Photonics Technology Letters, 2007

We show that impairments related to stimulated Brillouin scattering in radio-over-fiber transmiss... more We show that impairments related to stimulated Brillouin scattering in radio-over-fiber transmission can be strongly suppressed with the proper choice of a segmented single-mode optical fiber. As a result, low error vector magnitude (EVM) can be achieved for remote antenna feeding of IEEE 802.11a/g wireless LAN signals, resulting in 1% EVM degradation after 20-km transmission at 14 dBm.