MIT researchers discover platform that manipulates organic molecules’ emission


qdot-images-3.jpgEnhancing and manipulating the light emission of organic molecules is at heart of many important technological and scientific advances, including in the fields of organic light emitting devices, bio-imaging, bio-molecular detection. Researchers at MIT have now discovered a new platform that enables dramatic manipulation of the emission of organic molecules when simply suspended on top of a carefully designed planar slab with a periodic array of holes: so-called photonic crystal surface.

 

Influenced by the fast and directional emission channels (called ‘resonances’) provided by the photonic crystal surface, molecules in the solution that are suspended on top of the surface no longer behave in their usual fashion: instead of sending light isotropically into all directions, they rather send light into specific directions.

The researchers say that this platform could also be applied to enhance other type of interactions of light with matter, such as Raman scattering. Furthermore, this process applies to any other nano-emitters as well, such as quantum dots.

Physics Professors Marin Soljacic and John Joannopoulos, Associate Professor of Applied Mathematics Steven Johnson, Research scientist Dr. Ofer Shapira, Postdocs Dr. Alejandro Rodriguez, Dr. Xiangdong Liang, and graduate students Bo Zhen, Song-Liang Chua, Jeongwon Lee report this discovery as featured in Proceedings of the National Academy of Sciences.

“Most fluorescing molecules are like faint light bulbs uniformly emitting light into all directions,” says Soljacic. Researchers have often sought to enhance this emission by incorporating organic emitters into sub-wavelength structured cavities that are usually made out of inorganic materials. However, the challenge lies in an inherent incompatibility in the fabrication of cavities for such hybrid systems.

Zhen et al present a simple and direct methodology to incorporate the organic emitters into their structures. By introducing a microfluidic channel on top of the photonic crystal surface, organic molecules in solution are delivered to the active region where interaction with light is enhanced. Each molecule then absorbs and emits significantly more energy with an emission pattern that can be designed to be highly directional. “Now we can turn molecules from being simple light bulbs to powerful flashlights that are thousands of times stronger and can all be aligned towards the same direction,” says Shapira, the senior author of the paper.

This discovery lends itself to a number of practical applications. “During normal blood tests, for example,” adds Shapira, “cells and proteins are labeled with antibodies and fluorescing molecules that allow their recognition and detection. Their detection limit could be significantly improved using such a system due to the enhanced directional emission from the molecules.”

The researchers also demonstrated that the directional emission can be turned into organic lasers with low input powers. “This lasing demonstration truly highlights the novelty of this system,” says the first author Zhen. For almost any lasing system to work there is a barrier on the input power level, named the lasing threshold, below which lasing will not happen. Naturally, the lower the threshold, the less power it takes to turn on this laser. Exploring the enhancement mechanisms present in the current platform, lasing was observed with a substantially lower barrier than before: the measured threshold in this new system is at least an order of magnitude lower than any previously reported results using the same molecules.

Source: Massachusetts Institute of Technology, Institute for Soldier Nanotechnologies

SPIE Photonics West, February in San Francisco: QMC to Present


QDOTS imagesCAKXSY1K 8SPIE Photonics West 2013 expects to see growth from the largest-yet Biomedical Optics technical program and BiOS Expo. With strong programs in LASE, OPTO, and MOEMS-MEMS as well, the international event is expected to draw more than last year’s 20,000 attendees to the Moscone Center in San Francisco, California, 2-7 February.

Note To Readers: Invited Speaker & Exhibitor At The “Emerging Molecular Diagnostics Parterning Furum” Feb 11-12 at Moscone Center San Francisco.

Mr. Stephen Squires (Quantum Materials Corporation) topic is “Flow Chemistry Process Biocompatable Inorganic High Quantum Yield Tetrapod Quantum Dots For The Next Generation of Diagnostic Assays, Multiplexed Drug Delivery Platforms and POC Devices”.

Tetra-Pod quantum dots can fulfill so many needs in the pharma and biomedicine area.

Nearly 1300 exhibiting companies are expected with 200 product launches. A SPIE Startup Challenge will offer cash award sponsored by Jenoptik to offer aspiring entrepreneurs venture capital exposure and mentoring.

Approximately 235 exhibiting companies are expected for the BiOS Expo. Available space in the exhibition halls is filling fast, and late-booking companies for the Photonics West Exhibition face the prospect of a waiting list.

Technical conference presentations are up approximately 5% over last year, with more than 4450 organized into four topical areas ― BiOS, LASE, MOEMS-MEMS, and OPTO ― and the Green Photonics virtual symposium.

The BiOS program provides the latest information on biomedical optics, diagnostics and therapeutics, biophotonics, molecular imaging, optical microscopy, optical coherence tomography, and optogenetics.

New conferences reflect important advances in personalized medicine:

  • Terahertz and Ultrashort Electromagnetic Pulses for Biomedical   Applications
  • Optogenetics and Hybrid-Optical Control of Cells
  • Optical Methods in Developmental Biology
  • Bioinspired, Biointegrated, Bioengineered Photonic Devices.

Opening-day speakers in the popular BiOS Hot Topics session include:

  • Ernst Bamberg (Max Planck Institute), optogenetics and hybrid-optical control of cells
  • Ben Potsaid (Massachusetts Institute of Technology), MEMs tunable VCSEL technology for ultrahigh-speed OCT
  • Dan Oron (Weizmann Institute of Science), patterned multiphoton photoactivation in scattering tissue by temporal focusing
  • Jonathan Sorger (Intuitive Surgical), clinical requirements for optical imaging in medical robotics
  • Bernard Choi (Beckman Laser Institute), camera-based functional imaging of tissue hemodynamics
  • Mathias Fink (Institute ESPCI, CNRS), multiwave approach to elasticity imaging for cancer detection
  • Joe Culver (Washington University in St. Louis), functional optical imaging of the brain
  • Vladimir Zharov (University of Arkansas for Medical Sciences), photoacoustic flow cytometry.

The MOEMS-MEMS program has seen a jump in submissions, driven primarily by more papers in the areas of microfluidics, bioMEMS, and medical microsystems, along with papers on micro-optics, and adaptive optics. Papers explore how MEMS and MOEMS will enable the mass-produced miniaturized products and integrated systems of the future. Plenary speakers are:

  • Bozena Kaminska (Simon Fraser University), future systems with nano-optics contributions
  • Aaron Knoblach (GE Global Research), optical MEMS pressure sensors for geothermal well monitoring
  • Kaili Jiang (Tsinghua University), super-aligned carbon nanotubes.

Presentations in the OPTO program cover the latest developments in a broad range of optoelectronic technologies and their integration for a variety of commercial applications. Topics include silicon photonics, photonic crystals, optoelectronics, semiconductor lasers, quantum dots, and nanophotonics. Plenary speakers are:

  • Markus Aspelmeyer (University of Vienna), quantum optomechanics
  • Richard Soref (University of Massachusetts, Boston), group IV photonics for the mid-IR
  • Miles Padgett (University of Glasgow), optical angular momentum.

The LASE program focus is on laser sources, lasers for manufacturing, lasers for micro/nanoengineering, and other applications. Highlights include laser resonators, fiber, solid state, and high-power lasers for materials processing and the world’s largest concentration of semiconductor laser/LED content.

Plenary speakers are:

  • Wim Leemans (Lawrence Berkeley National Lab), particle acceleration and TeV physics and compact x-ray and gamma-ray sources
  • Martin Wegener (Karlsruhe Institute of Technology), 3D metamaterials made by direct laser writing
  • Geert Verhaeghe (Faurecia Autositze), remote laser welding in automotive production.

A virtual symposium on Green Photonics reflects the integration of enabling photonics technologies in solutions to the world’s environmental and energy challenges. More than 65 papers from throughout the program are highlighted in this symposium.

Executive panels on market trends in photonics, sustainable technology, and silicon photonics and photonics integrated circuits and a talk by SPIE CEO Eugene Arthurs on government initiatives and opportunities for growth in photonics provide strong industry-focused content.

More than 70 short courses providing CEU accreditation provide a valuable resource for working professionals, spanning essential topics in optical, biomedical, laser, manufacturing, and optoelectronics engineering.

A comprehensive set of professional development workshops and other activities for students and early career professionals are offered, and the event will provide numerous opportunities for valuable networking throughout the week.

Accepted papers will be published in the SPIE Digital Library as soon as approved after the meeting, and in print volumes and digital collections.