Widely tunable laser source for gas sensing applications

In gas detection systems based on a single absorption line, wide-range, precision-tunable, continuous-wave laser sources are desired in order to allow for accurate targeting and measuring absorption profiles of particular gas species. A widely tunable ring laser using an intra-cavity wavelength tuning mechanism based on asymmetric Mach-Zehnder interferometers has been realized in the form of a monolithic indium phosphide photonic integrated circuit following a generic photonic integration approach. Furthermore, such integration technology enables the possibility of a co-integration of multiple lasers on a single photonic chip and allowing a gas detection system to monitor a few gas species simultaneously

Widely tunable monolithically integrated lasers using intracavity Mach-Zehnder interferometers

Using monolithic integration technology we have designed and fabricated tunable lasers in the 1.5 µm region with a demonstrated tuning range of 60 nm and single mode operation. This performance is achieved using intracavity tunable Mach-Zehnder interferometers that use voltage controlled phase modulators. In this paper we will discuss design considerations and advantages of such tunable lasers

Particle Splitting for Monte-Carlo Simulation of the National Ignition Facility

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is scheduled for completion in 2009. Thereafter, experiments will commence in which capsules of DT will be imploded, generating neutrons, gammas, x-rays, and other reaction products that will interact in the facility's structure. In order to understand and minimize the exposure of workers within the facility to prompt and delayed (activation) dose, they have developed a model for the facility using the three-dimensional Monte Carlo particle transport code, TART. To obtain acceptable statistics in a reasonable amount of time, biasing techniques are employed. In an effort to improve efficiency, they are studying the optimization of particle splitting using geometrically similar, but much simpler models. They are discussing their techniques and results

Increased bit rate direct modulation AMO-OFDM transmission by optical injection using monolithically integrated lasers

Experimental and simulation work, presented in this letter, demonstrates for the first time how the monolithic integration of two single-mode lasers in a master-slave configuration, can substantially increase the achievable bit rate of a direct modulation adaptively modulated optical orthogonal frequency-division multiplexing (AMO-OFDM) system. The Levin-Campello algorithm is applied to select the OFDM bit and power loading scheme used for each system configuration. Improvement in terms of data throughput due to injection is measured for several transmission distances with the improvement in performance presented in terms of error vector magnitude per OFDM subcarrier

Recent advances in the photonic integration of mode-locked laser diodes

Mode-locked fiber and solid state lasers have played an essential role in several scientific and technological developments. The integration of mode-locked lasers on chips could enable their use in a wide range of applications. The advancement of semiconductor mode-locked laser diodes has been going on for several decades, but has recently seen the development of novel devices based on generic InP and III-V-on-silicon photonic integration platforms. These photonic integration platforms enable the use of standardized components and low-loss waveguides within the laser cavity, allowing for the design of advanced extended cavities. In this manuscript we give a review of these novel devices and compare their performance