Optomechanics is an emerging field which focuses on exploring the mechanical effects of light. Optical trapping and manipulation of micro-objects are becoming increasingly important techniques in biotechnology and micro-fabrication due to their non-contact nature and inherent high precision.

Resonant cavity trapping presents a novel solution for nanoparticle manipulation. In a resonant cavity, the optical field is significantly enhanced and thus effectively reduces the power threshold for stable trapping. The cavity environment also facilitates analysis using sensitive cavity-enhanced spectroscopic techniques such as fluorescence or Raman spectroscopy.

In this project, we investigate both theoretically and experimentally novel cavity-enhanced techniques for nanoparticle and molecular manipulation using light. The project will ultimately lead to the Holy Grail of a single-molecule detection platform which combines both sensitive detection as well as nano-scale molecular manipulation capabilities.

COLLABORATORS
Professor Kenneth Crozier, Harvard University

PUBLICATIONS

(Postdeadline) "Optical Trapping of Nanoparticles in Resonant Cavities: Optical Tweezers with Single Particle Selectivity," Frontiers in Optics, San Jose, CA (2009).

S. Lin, J. Hu, L. C. Kimerling, and K. Crozier, "Design of Nanoslotted Photonic Crystal Waveguide Cavities for Single Nanoparticle Trapping and Detection," Opt. Lett. 34, 3451-3453 (2009).

J. Hu, S. Lin, L. C. Kimerling, and K. Crozier, "Optical trapping of nanoparticles in resonant cavities," submitted to Phys. Rev. A

In this project, we aim at developing a label-free bio-molecular detection technology for making a highly sensitive, low-cost, integrated sensors. Such sensors fulfill the pressing needs of an array of applications, such as point-of-care detection of biomarkers for medical diagnosis and monitoring, high-throughput screening in pharmaceutical drug discovery, as well as advanced intelligence and biodefense applications.

The sensor works by detecting refractive index changes induced by surface binding of target molecules. Very high sensitivity can be achieved by leveraging the strong resonant interaction between molecules and photons circulating in an optical resonator. The detection mechanism applies for a wide range of molecular species, including proteins (antigens), DNA strands and small molecules (e.g. drug molecules).

Highlights of the project include theoretical demonstration of the superior sensitivity of resonator sensing over other optical techniques such as surface plasmonic resonance, and experimental realization of sensitive molecular detection using high-Q chalcogenide glass optofluidic resonators. We are also actively exploring the technology commercialization for point-of-care disease diagnosis.

COLLABORATORS
Professor Vishal S. Vaidya, Harvard Medical School
Professor Yasha Yi, New York University & City University of New York

PUBLICATIONS

J. Hu, X. Sun, A. Agarwal, and L. C. Kimerling, "Design guidelines for optical resonator biochemical sensors," J. Opt. Soc. Am. B. 26, 1032-1041 (2009).

J. Hu, N. Carlie, N. Feng, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, "Planar waveguide-coupled, high-index-contrast, high-Q resonators in chalcogenide glass for sensing," Opt. Lett. 33, 2500-2502 (2008).

(Invited Review) L. Petit, J. Hu, N. Carlie, B. Zdyrko, T. Anderson, A. Agarwal, I. Luzinov, M. Richardson, L. C. Kimerling, and K. Richardson, "Development of novel integrated bio/chemical sensor systems using chalcogenide glass materials," Int. J. Nanotechnol. 6, 799-815 (2009).

(Invited) "Planar Chalcogenide Glass Microcavities: A Versatile Device Platform," 8th Pacific Rim Conference on Ceramic and Glass Technology, Vancouver, Canada (2009).

The ultimate goal of the project is to demonstrate a miniaturized, all-on-chip platform for ultra-sensitive detection of chemical vapors using infrared spectroscopy.

In this project, we leverage resonant cavity enhancement to dramatically improve the detection capabilities of infrared chemical sensors. The planar chalcogenide glass micro-resonators we invented are ideally suited for this purpose, given their wide infrared transparency and ultra-low optical loss after our specialty thermal reflow treatment.

On the detection technique front, we explore novel sensing mechanisms to capitalize on the cavity enhancement effects. Our recent theoretical analysis has shown that the novel techniques we are currently developing is five orders of magnitude more sensitive compared to conventional multi-pass infrared absorption spectroscopy, and is capable of detecting chemical molecules down to the ppt level, which qualifies this technique as one of the most sensitive methods for chemical vapor analysis.

We also collaborate closely with researchers in several institutes to develop new glass materials for improved optical performance, as well as novel polymer coatings for enhancing detection sensitivity and specificity. Device field testing will be conducted through collaborations with industrial partners.

COLLABORATORS
Professor Kathleen Richardson, Clemson University
Professor Igor Luzinov, Clemson University
Dr. Mark Allen, Physical Sciences Inc.

PUBLICATIONS

J. Hu, V. Tarasov, N. Carlie, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, "Fabrication and Testing of Planar Chalcogenide Waveguide Integrated Microfluidic Sensor," Opt. Express 15, 2307-2314 (2007).

J. Hu, N. Carlie, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, "Demonstration of chalcogenide glass racetrack micro-resonators," Opt. Lett. 33, 761-763 (2008).

J. Hu, N. Carlie, L. Petit, A. Agarwal, K. Richardson, and L. C. Kimerling, "Cavity-enhanced infrared absorption in planar chalcogenide glass resonators: experiment & analysis," J. Lightwave Technol. 27, 5240-5245 (2009).

(Invited Review) K. Richardson, L. Petit, N. Carlie, B. Zdyrko, I. Luzinov, J. Hu, A. Agarwal, L. C. Kimerling, T. Anderson, and M. Richardson, "Progress on the fabrication of on-chip, integrated chalcogenide glass (ChG)-based sensors," J. Nonlinear Opt. Phys. Mater. 19, 75-99 (2010).

(Invited) "Integrated chalcogenide waveguide resonators for mid-IR sensing: Leveraging material properties to meet fabrication challenges," Opt. Express, in preparation

(Invited) "Development of chipscale chalcogenide glass based infrared chemical sensors," to be presented at SPIE Photonics West, San Francisco, CA (2011).