Ph.D. Dissertation Defense

High Power Mid-infrared Quantum Cascade Laser Array
for Standoff Photoacoustic Chemical Detection

Xing Chen

1:00-3:00pm Friday, 17 May 17 2013, TRC CASPR Conference Room

Quantum cascade lasers (QCLs) are compact, portable, powerful semiconductor laser sources with emission wavelengths from mid-infrared (mid-IR) to terahertz (THz) regions of the electromagnetic spectrum. Mid-IR (i.e. wavelengths from 3 to 20 µm) QCLs are of great importance in a wide range of applications such as trace gas sensing, environmental monitoring, free space communication, medical diagnosis and so on. High power QCLs are particularly important to applications such as infrared counter measure (IRCM) and standoff chemical detections. In such applications, the system performances critically depend on the amount of power a QCL can produce. This dissertation includes two major studies: the first part of the dissertation includes design, fabrication and characterization of high power mid-IR QCL arrays; the second part involves standoff chemical detection using QCLs as laser sources and photoacoustic effect as sensing technologies.

In the first part of the dissertation, we design, fabricate and characterize multi-emitter QCL arrays consisting of multiple narrow laser stripes. Simulation results indicate that the proposed multi-emitter laser arrays present much better thermal performance than a broad area laser device, while having the same thermal management ability as a single narrow stripe device. We have successfully fabricated edge emitting and surface emitting QCL arrays with 5 and 16 emitters. Experimental results show that, with the same laser cavity length, a QCL array with 5 emitters produces over 3 times more power than a single emitter laser device. QCL array with 16 emitters generates about 4 W output peak power at wavelength ~7.9 µm. We have also fabricated surface emitting QCL arrays and demonstrated single mode emission.

The second part of the dissertation involves using high power mid-IR QCLs to perform standoff chemical detections based on photoacoustic sensing technologies. Photoacoustic effect is a light-matter interaction effect that involves generation of acoustic waves when a medium absorbs electromagnetic energy from light. It has been known as a sensitive spectroscopic technique for chemical sensing.

Standoff photoacoustic chemical detection with distance more than 41 feet using quantum cascade laser operated at relatively low power, less than 40 mW, is demonstrated. A simplified theoretical model is developed for pulsed laser photoacoustic effect in open-air environment. The standoff photoacoustic signal can be calibrated as a function of different parameters such as laser pulse energy, gas vapor concentration and detection distance. The results yield good agreements with theoretical model. Standoff detection of solid phase explosive chemicals has also been demonstrated by the use of an ultra-sensitive microphone and acoustic reflector. More than 8 feet detection distance is obtained for standoff photoacoustic sensing of explosives.

Committee: Drs. Fow-Sen Choa (Chair), Brian Cullum, Yordan Kostov, Ryan Robucci, Chen-Chia Wang and Li Yan

Contact: Ben Souder

Email: bensouder@targetgov.com

Phone: 443-543-5067

For Immediate Release:

Local Business Woman Speaks in Oxford Regarding Women in the Global Economy

Gloria Larkin participates in Women in the World Economy Forum 2013- PowerShift: Women Changing The Game

Baltimore, Maryland – May 14, 2013 - Gloria Larkin, President of TargetGov, has been invited to speak at the Women in the World Economy Forum 2013- Power Shift: Women Changing the Game. The event will be held at the University of Oxford Said Business School, United Kingdom, May 20-21, 2013. The theme for this inaugural symposium is women as entrepreneurs. The Forum includes keynote speakers, panel sessions, a Union debate, a case study and book signings. Selected speakers and participants include global innovators, experts who study female entrepreneurs, policy activists, philanthropists, universities and authors. For more information visit http://www.sbs.ox.ac.uk/newsandevents/conferences/wwef/Pages/default.aspx

Gloria is being featured on the Collective Action panel. As Vice Chair of the Women Impacting Public Policy (WIPP) Educational Foundation Board, Gloria will be representing WIPP and discussing The Economic Blueprint which sets a bold, comprehensive set of public policy expectations on behalf of the women business owner community. WIPP represents over 1,000,000 U.S. business women and advocates for and on behalf of women in business in the legislative processes, creates economic opportunities and builds bridges and alliances to other small business organizations. Forough Ghahramani, board member of WIPP and Associate Dean of the College of Business and Management at DeVry University's New Brunswick campus, is also attending.

“Strong women build strong economies. WIPP is extraordinarily proud to be among the leadership present at the Women in the World Economy Forum and to be represented by Gloria Larkin, Vice Chair of WIPP's Education Foundation.” Said Barbara Kasoff, President of WIPP, “WIPP is creating a model to foster entrepreneurship and build strong, vibrant collaborative worldwide economies that will facilitate trade and foster business relationships among women entrepreneurs.”

Fellow panelists include Pacita U Juan, President, Women’s Business Council of the Philippines and Francisca Valdés, Founder & Executive Director, Mujeres Empresarias. Pacita has founded many startups, including a coffee shop chain that rivals Starbucks in the Philippines. She has written several books on coffee and is an advocate of women’s empowerment through business. Francisa created Mujeres Empresarias as a networking and service organization created for the support of women entrepreneurs in Chile.

In addition to being featured on the panel, Mrs. Larkin will participate in the book signing part of the Forum, where her book “The Basic Guide to Government Contracting” will be available to purchase.

About Gloria Larkin:

Gloria Larkin, National Marketing and Business Expert, is President of TargetGov. Larkin has been interviewed on MSNBC, quoted in the Wall Street Journal, Forbes, and TheStreet.com. She is an expert author with articles regarding federal business development published in local, regional, national and international publications. She is also the author of two books: “The Basic Guide To Government Contracting” (book & Kindle) and “The Veterans Business Guide: How to Build a Successful Government Contracting Business” now in the fourth printing (book & Kindle). TargetGov clients have won federal contracts worth billions of dollars and the company focuses on government procurement and related business development and marketing services including minority certification services, contract development, proposal management, contract administration and expert federal contracting services.

About Saïd Business School:

The Saïd Business School is one of Europe's youngest and most entrepreneurial business schools. An integral part of the University of Oxford, the School embodies the academic rigour and forward thinking that has made Oxford a world leader in education.

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Almost every business has a web presence these days; from single page ‘business card’ style sites, to million+ product e-commerce hubs, owning a website is as universal as taxes. Of course, there are new startups, but even in those cases entrepreneurs tend to have bought a domain name, or thrown up a template.

It’s no surprise then that the bread and butter for most web designers is not site design, but redesign.

On the surface, redesign looks easy; you have a starting point, with some real world data on what is and isn’t working for your client. Once you dive a little deeper you’ll find redesigns are a minefield of competing ideas. It will take all of your skill to exploit the current site’s successes and identify its failings.

Moreover, there is no room for error in a redesign. Clients have often been burned by poor results in the past and are more cautious. They’re more likely to have spent a long time analyzing their site themselves. They’re probably frustrated by the need for a redesign, or what is sometimes worse, they’re so excited by it that they’re spilling over with ideas, many of which aren’t appropriate.

Happily, there’s a lot of great advice available on how to tackle this tricky task and one of the best sources is Smashing Magazine’s current set of eBooks. Worth nearly $40, our sister site MightyDeals.com has arranged a 40% discount on this great set:

“Smashing Book #3: Redesign The Web” is 340 pages of advice on vital subjects like: the business aspects of redesigning a site; platform considerations; upgrading code to HTML5 and CSS3; important considerations of mobile design; and of course, going responsive.

“Smashing Book #3 1/3” takes redesigns to the next level: insert ‘story’ into your redesign to engage users; rethink and repurpose navigation to improve UX; make the site’s content work harder; and there’s even a detailed case study of Smashing’s own redesign.

“Essentials of Mobile Design”, “Mobile Design Patterns”, “Designing For Android” and “Designing For iPhone” cover the essentials of the biggest reason clients cite for redesigning their site: mobile compatibility. Learn the difference between mobile sites and apps, marketing, and the all important responsive techniques you’ll need.

The set of six books comes in DRM-free format, as PDFs, ePUBs and MOBIs, so you can study them however and wherever you like. Head over to MightyDeals.com now to take advantage of this great offer.

Have you read Smashing Magazine’s redesign series? What did you learn? Let us know in the comments.

Featured image/thumbnail, uses surface image via Shutterstock.

20 One-Page Responsive Templates with Parallax Effect – only $19!

Almost every business has a web presence these days; from single page ‘business card’ style sites, to million+ product e-commerce hubs, owning a website is as universal as taxes. Of course, there are new startups, but even in those cases entrepreneurs tend to have bought a domain name, or thrown up a template.

It’s no surprise then that the bread and butter for most web designers is not site design, but redesign.

On the surface, redesign looks easy; you have a starting point, with some real world data on what is and isn’t working for your client. Once you dive a little deeper you’ll find redesigns are a minefield of competing ideas. It will take all of your skill to exploit the current site’s successes and identify its failings.

Moreover, there is no room for error in a redesign. Clients have often been burned by poor results in the past and are more cautious. They’re more likely to have spent a long time analyzing their site themselves. They’re probably frustrated by the need for a redesign, or what is sometimes worse, they’re so excited by it that they’re spilling over with ideas, many of which aren’t appropriate.

Happily, there’s a lot of great advice available on how to tackle this tricky task and one of the best sources is Smashing Magazine’s current set of eBooks. Worth nearly $40, our sister site MightyDeals.com has arranged a 40% discount on this great set:

“Smashing Book #3: Redesign The Web” is 340 pages of advice on vital subjects like: the business aspects of redesigning a site; platform considerations; upgrading code to HTML5 and CSS3; important considerations of mobile design; and of course, going responsive.

“Smashing Book #3 1/3” takes redesigns to the next level: insert ‘story’ into your redesign to engage users; rethink and repurpose navigation to improve UX; make the site’s content work harder; and there’s even a detailed case study of Smashing’s own redesign.

“Essentials of Mobile Design”, “Mobile Design Patterns”, “Designing For Android” and “Designing For iPhone” cover the essentials of the biggest reason clients cite for redesigning their site: mobile compatibility. Learn the difference between mobile sites and apps, marketing, and the all important responsive techniques you’ll need.

The set of six books comes in DRM-free format, as PDFs, ePUBs and MOBIs, so you can study them however and wherever you like. Head over to MightyDeals.com now to take advantage of this great offer.

Have you read Smashing Magazine’s redesign series? What did you learn? Let us know in the comments.

Featured image/thumbnail, uses surface image via Shutterstock.

20 One-Page Responsive Templates with Parallax Effect – only $19!

W3C announced today a Workshop on Social Standards: The Future of Business, 7-8 August 2013, in San Francisco, USA. The event is hosted by AppFusions, sponsored by IBM, and jointly organized with the OpenSocial Foundation. The goal of this workshop is to bring together social business experts and social technology experts to discuss the use-cases that existing specifications and standards don't adequately address, and understand where new standards are needed. This Workshop is open in particular to social business leaders and strategists, federated and decentralized social Web technologists, security experts, and developers. W3C membership is not required to participate. The event is open to all. All participants are required to submit a position paper by 1 July 2013.

What’s an SVG, and why do I have to use it? SVG, or Scalable Vector Graphics, are very small in file size and are great for retina displays. Vector graphics have an advantage over pixel formats like .gif or .jpg as they don’t deal with resolution. SVGs can scale to any size and not lose clarity. All SVGs are usually smaller in file size than raster graphics.

Treehouse Illustrator teacher Mat Helme will help you get started saving resolution independent SVG files in this Treehouse Quick Tip.

The post Quick Tip: Saving SVG Files in Adobe Illustrator appeared first on Treehouse Blog.

A report summarizing the MultilingualWeb workshop in Rome is now available from the MultilingualWeb site. It contains a summary of each session with links to presentation slides and minutes taken during the workshop in Rome. The workshop was a huge success, with approximately 150 participants, focus sessions on topics like Internationalized Domain Names, Best Practices for Multilingual Linked Open Data (BP-MLOD) and an implementation showcase of the upcoming ITS 2.0 specification. The Workshop was hosted by FAO, sponsored by the EU-funded QTLaunchPad project and by Verisign. A new workshop in the MultilingualWeb series is planned for 2014. Learn more about the Internationalization Activity.