Genevieve Plant

Chirped lasers dispersion spectroscopy implemented with single- and dual-sideband electro-optical modulators

We report new approaches for signal generation in Chirped Laser Dispersion Spectroscopy (CLaDS). Two optical arrangements based on electro-optical modulators significantly reduce CLaDS system complexity and enable optimum performance when applied to detection of GHz-wide molecular transitions. Proof-of-principle experiments in the near-infrared spectral range are presented and potential strategies for application in the mid-infrared are discussed.

Field Test of a Remote Multi-Path CLaDS Methane Sensor.

Existing technologies for quantifying methane emissions are often limited to single point sensors, making large area environmental observations challenging. We demonstrate the operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy (CLaDS) for quantification of atmospheric methane concentrations over extended areas, a technology that shows potential for monitoring emissions from wetlands.

Fundamental Noise Characteristics of Chirped Laser Dispersion Spectroscopy

Analysis of the fundamental noise characteristics of chirped laser dispersion spectroscopy (CLaDS) is reported. The noise performance of CLaDS under shot noise conditions is investigated and the results are compared to that of direct laser absorption spectroscopy (DLAS). For single spectral point detection, the CLaDS detection limit is a factor of 6 higher than that of DLAS. In the case of full spectral fitting with accurate representation of the noise characteristics and the less complex baseline correction in CLaDS, both techniques show comparable fundamental limit of performance in trace-chemical detection.

Gas sensing fiber network with simultaneous multi-node detection using range-resolved chirped laser dispersion spectroscopy

We present a laser-spectroscopic method for continuous and simultaneous interrogation of multiple passive gas sensor nodes in a fiber based sensor network. Enabled by chirped laser dispersion spectroscopy, methane leak detection is demonstrated as an example application.

Chirped Laser Dispersion Spectroscopy for Remote Sensing of Methane

A new near-IR chirped laser dispersion spectroscopy system operating at 1.65µm is presented. We demonstrate its application to remote sensing of methane in the atmosphere.

Improved Signal Processing for Distributed Sensing Network based on Chirped Laser Dispersion Spectroscopy

A centralized detection in a network of Chirped Laser Dispersion Spectroscopy (CLaDS) sensors requires efficient signal processing. The optimization of CLaDS signal processing and development of a custom digital signal processing unit in place of conventional bench-top instruments that prevent previously developed CLaDS systems from achieving optimum performance is discussed.

FPGA-based chirped laser dispersion spectrometer

We present a FPGA based fast data acquisition system which enables continuous, real time chirped laser dispersion spectroscopic chemical sensing. System performance is evaluated using atmospheric methane detection sensing as an example application.

Remote Sensing of Atmospheric Methane with Simultaneous Ranging Using Chirped Laser Dispersion Spectroscopy

We present a new sensing technology that allows for simultaneous sensing and ranging using chirped laser dispersion spectroscopy (CLaDS). In conjunction with previous works demonstrating the effectiveness of CLaDS for remote sensing, this new configuration yields spectroscopic and ranging information from a single measurement, and is implemented for continuous, multi-path detection of atmospheric methane. 1. INTRODUCTION In remote sensing of atmospheric trace gases, knowledge of the path length is crucial to accurate extraction of the species concentration. However, in most case, this optical path length must be known beforehand or measured separately. Currently, the standard technique for atmospheric ranging and sensing is lidar (light radar), where pulsed light probes the target environment. The timing of the returned backscatter is used to extract the path length, and the received intensity is analyzed to determine the path-integrated concentration. We present an alternative, continuous wave (CW), approach based on the fundamentals of chirped laser dispersion spectroscopy (CLaDS). A proof-of-concept study has shown that both species concentration and path length can be extracted from a single, CW measurement. Development of a system that combines this CW sensing and ranging feature, with a CLaDS system that monitors atmospheric methane will be presented.

Fundamental limits in chirped laser dispersion spectroscopy

We present performance analysis of chirped laser dispersion spectroscopy (CLaDS) under shot noise limited conditions. A comparison to direct laser absorption spectroscopy (DLAS) is also provided.

Remote optical sensing network for gas monitoring based on laser spectroscopy over hybrid TDM/WDM-PONs

We propose an optical gas sensing network directly overlaid onto optical access networks, hybrid TDM/WDM-PONs. Centralized remote gas monitoring is demonstrated using three different sensing technologies: Chirp Laser Dispersion Spectroscopy (CLaDS), Direct Laser Absorption Spectroscopy (DLAS) and tunable diode laser absorption spectroscopy (TDLS). DLAS performs fast threshold detection while CLaDS provides quantitative information about the gas. Additionally, TDLS utilizes a cost-effective solution for multiple gases detection. The results confirm that centralized remote gas sensing can be realized in optical communication networks using standard single-mode fiber (SMF), which provides a real time, low cost, and maintenance-free solution.