Nanoscale resolution interrogation scheme for simultaneous static and dynamic fiber Bragg grating strain sensing

A combined interrogation and signal processing technique which facilitates high-speed simultaneous static and dynamic strain demodulation of multiplexed fiber Bragg grating sensors is described. The scheme integrates passive, interferometric wavelength-demodulation and fast optical switching between wavelength division multiplexer channels with signal extraction via a software lock-in amplifier and fast Fourier transform. Static and dynamic strain measurements with noise floors of 1 nanostrain and 10 nanostrain/sqrt(Hz), between 5 mHz and 2 kHz were obtained. An inverse analysis applied to a cantilever beam set up was used to characterise and verify strain measurements using finite element modeling. By providing distributed measurements of both ultahigh-resolution static and dynamic strain, the proposed scheme will facilitate advanced structural health monitoring

High-speed interferometric FBG interrogator with dynamic and absolute wavelength measurement capability

A passive, interferometric wavelength demodulation technique has been extended to measure the absolute wavelengths of a multiplexed array of fiber Bragg grating sensors. The scheme retains its original strain resolution of 10 nε/√{Hz}. A proof-of-concept interrogation system was able to determine the absolute wavelength of Bragg peaks to within 20 pm (17 με). Static and dynamic Bragg grating strains were accurately demodulated in both absolute and relative wavelength measurement modes. This demonstration indicates that interferometric techniques are able to provide absolute, static and dynamic measurements of strain within a single platform

Primal Scream

Artwor

Solid-state interferometric interrogator and multiplexer for high-speed dynamic and absolute FBG wavelength measurement

We present a solid-state FBG array interrogator and multiplexer capable of determining absolute FBG wavelengths and of providing high-speed, high-resolution static and dynamic measurements. Using a described procedure, deployable on multiplexing passive-interferometric schemes, the system is able to determine initial sensor wavelengths and thereafter track wavelength changes with interferometric resolution. The scheme allows high-resolution interrogation of FBG sensor arrays to be applied to many industrial applications, where previously the lack of combined absolute and quasi-static wavelength measurement precluded the use of interferometric techniques. Using a preliminary laboratory embodiment, we demonstrate a wavelength determination accuracy of <0.3 nm and a measurement resolution of 10 fm/√Hz, and propose pathways to improved performance and miniaturisation

Self Portrait

Artwor

Optical generation and wireless transmission of 60 GHz OOK signals using gain switched laser

We present a novel, simple and cost effective system for optical millimeter-wave generation and transmission of 3 Gbps data based on gain switching. System performance has been investigated, including wireless transmission and power budget analysis

Assessing the Effectiveness of the Federal Reserve’s Quantitative Easing Policy in Lowering Long-Term Interest Rates

This project looks at the effectiveness of Quantitative Easing on lowering long-term interest rates. To come up with an answer I look through three separate channels in which QE works to lower long-term rates: the speculation channel, inflations expectation channel, and portfolio balance channel. In examining these channels and their respective effects, I combine relative channel and general economic theory with data relative to each channel such as long-term yields, inflation expectation data, public holdings of federal debt, and much more in order to understand whether QE was at the forefront of the reduction in yields. Through these channels, we can see that QE did not have a major impact on reducing long-term interest rates as speculation can be only be credited for short-term rate reductions. Inflation expectations caused an increase in rates through price declines and resulting rate increases. The portfolio balance effect is limited; term premiums decreased, lowering yields, however, much of the decrease in yields came from investor prioritization of safe bonds, leading to a continued reduction of yield reductions. As a result, it is much more likely that the reduction of long-term rates can be credited to a struggling economy that promoted risk-averse behavior

An IR-UWB photonic distribution system

Experimental results are presented for a novel distribution system for an impulse radio ultra-wideband (UWB) radio signals employing a gain-switched laser. The pulse position modulated short optical pulses with a bit rate of 1.25 Gb/s are transmitted over fiber to a remote antenna unit, where the signal is converted to the electrical domain and undergoes spectral shaping to remove unwanted components according to UWB requirements. An experimental radio terminal has also been constructed to enable bit-error-rate measurements to be carried out. These experiments show that the optical distribution system will be capable of supporting the radio part of the system

Demonstration of wavelength packet switched radio-over-fiber system

The authors present a novel concept of employing optical wavelength packet switching in radio-over-fiber access networks. In such a system, the tunable laser (TL) would be employed as a transmitter in the central station. The optical carrier generated by this device would be externally modulated with the data signal upconverted to an RF frequency before being sent to the appropriate base station (BS). If each of the BSs is assigned a unique wavelength, the addressing and routing of traffic could be performed on a packet-by-packet basis with the TL switching between the wavelength assigned to different BS