Optical pulse durations of an InAs two-section passively mode-locked quantum dot laser with a proton bombarded absorber section reduce from 8.4 ps at 250K to 290 fs at 20 K, a factor of 29, with a corresponding increase in optical bandwidth. Rate equation analysis of gain and emission spectra using rate equations suggests this is due to the very low emission rate of carriers to the wetting layer in the low temperature, random population regime which enables dots across the whole inhomogeneous distribution to act as independent oscillators. (C) 2013 AIP Publishing LLC

We examine in detail the relation between the optical gain spectra, mode-locked optical emission spectra, and temporal optical pulse widths as a function of temperature between 80 and 300 K in passively mode-locked InAs quantum dot lasers. By increasing the length of the active region, we can decrease the threshold gain requirement for mode locking. At 300 K, where the dot states and wetting layer are close to thermal equilibrium, the bandwidth of the optical emission spectra and temporal optical pulse width remain largely unaffected when the threshold gain requirement is reduced. At 80 K, where the dots are randomly populated, there is a near doubling of the optical bandwidth for the same reduction of the threshold gain requirement and a corresponding decrease in the temporal optical pulse width. Rate equations, which take explicit account of the photon density in the cavity, are used to qualitatively highlight the key parameters, which are responsible for increasing the optical bandwidth in the random population regime.

The key sectors, strategies, and goals are outlined in the table below: ENERGY SECTOR STRATEGIES 2030 GOALS Electricity (Generation and Delivery) Align electricity regulatory and policy framework with clean energy goals Renewable Portfolio Standard: 40% of delivered MWh renewable energy Increase certainty in the process for developing new renewable energy Deploy renewable generation and grid infrastructure Explore next generation technologies/new applications of existing technologies End Use Efficiency Align efficiency regulatory and policy framework with clean energy goals Energy Efficiency Portfolio Standard: 4,300 MWh reduced Retrofit residential and commercial existing buildings Strengthen new construction policies/building codes Identify non-building related energy efficiency measures Transportation Improve standard vehicle efficiency of fleet Reduce petroleum used for ground transportation by 70%* Reduce vehicle miles traveled (VMT) Incorporate renewable fuels into transportation sector Accelerate the deployment of electric vehicles (EVs) and related infrastructure Fuels Evaluate local agricultural industry and support its development Meet as much of in-State demand for renewable fuels as is feasible Invest in key infrastructure at scale Evaluate and develop renewable fuel processing infrastructure Match potential fuels supply to sources of in-State demand *HCEI will develop an expanded understanding of the needs of the large buyers in the aviation and defense sector. In the future, marine and aviation biofuel alternatives may be substituted to help meet the goal by displacing the equivalent of 70% of ground transportation demand with non-fossil fuels.

No abstract

No abstract