Optically active rare-earth Neodymium (Nd) ions are integrated in Niobium (Nb) thin films forming a new quantum memory device (Nd:Nb) targeting long-lived coherence times and multi-functionality enabled by both spin and photon storage properties. Nb is implanted with Nd spanning 10-60 keV energy and 1013-1014 cm-2 dose producing a 1- 3% Nd:Nb concentration as confirmed by energy-dispersive X-ray spectroscopy. Scanning confocal photoluminescence (PL) at 785 nm excitation are made and sharp emission peaks from the 4F3/2 -< 4I11/2 Nd3+ transition at 1064-1070 nm are examined. In contrast, un-implanted Nb is void of any peaks. Line-shapes at room temperature are fit with Lorentzian profiles with line-widths of 4-5 nm and 1.3 THz bandwidth and the impacts of hyperfine splitting via the metallic crystal potential are apparent and the co-contribution of implant induced defects. With increasing Nd from 1% to 3%, there is a 0.3 nm red shift and increased broadening to a 4.8 nm linewidth. Nd:Nb is photoconductive and responds strongly to applied fields. Furthermore, optically detected magnetic resonance (ODMR) measurements are presented spanning near-infrared telecom band. The modulation of the emission intensity with magnetic field and microwave power by integration of these magnetic Kramer type Nd ions is quantified along with spin echoes under pulsed microwave π-π/2 excitation. A hybrid system architecture is proposed using spin and photon quantum information storage with the nuclear and electron states of the Nd3+ and neighboring Nb atoms that can couple qubit states to hyperfine 7/2 spin states of Nd:Nb and onto NIR optical levels excitable with entangled single photons, thus enabling implementation of computing and networking/internet protocols in a single platform.
RF photonic channelizers can overcome limitations of conventional electronic methods for analysis of wideband RF spectral content. Here, we will present a recent progress on the RF photonic channelizer systems that are based on optical parametric combs. These systems can analyze very wide RF bandwidths exceeding 100GHz, therefore providing essential capability for the applications demanding a wide-bandwidth spectral analysis. The RF channelizers being presented utilize parametric processes in the highly non-linear fiber mixers to generate a large number of RF signal copies in the optical domain. Two different implementations for generation of RF signal copies will be presented and compared: one using a parametric multicasting and another utilizing a direct comb modulation. Generation of optical combs spanning more than 10THz will be shown. We will also present two distinct system architectures for RF photonic channelizer system: one employing a periodic optical filter such as Fabry-Perot etalon to select channels from the signal comb, and another one utilizing a coherent detection between a frequency-locked signal comb and a parametrically generated local oscillator (LO) comb. The second scheme gives benefit of providing both in-phase and quadrature (I/Q) information on channelized intermediate frequency (IF) signals. We will present a system with 32 implemented channels using a filtered scheme and a 32-channel coherent system with a full-field detection implemented on one tunable channel. Sensitivity and dynamic range as well as benefits of both system architectures will be discussed.
Silicon-on-sapphire devices are attractive for the mid-infrared optical applications up to 5 microns due to the low loss of both silicon and sapphire in this wavelength band. Designing efficient couplers for silicon-on-sapphire devices presents a challenge due to a highly confined mode in silicon and large values of refractive index of both silicon and sapphire. Here, we present design, fabrication, and measurements of a mode-converting coupler for silicon-on-sapphire waveguides. We utilize a mode converter layout that consists of a large waveguide that is overlays a silicon inverse tapered waveguide. While this geometry was previously utilized for silicon-on-oxide devices, the novelty is in using materials that are compatible with the silicon-on-sapphire platform. In the current coupler the overlaying waveguide is made of silicon nitride. Silicon nitride is the material of choice because of the large index of refraction and low absorption from near-infrared to mid-infrared. The couplers were fabricated using a 0.25 micron silicon-on-sapphire process. The measured coupling loss from tapered lensed silica fibers to the silicon was 4.8dB/coupler. We will describe some challenges in fabrication process and discuss ways to overcome them.
Monitoring cancer after the first treatment requires ultra-sensitive personalized biosensors with high specificity.
We present here some of the nanoparticle based microfluidic techniques pursued at the Nano Tumor Center towards this
The compactness of VCSELs (Vertical Cavity Surface Emitting Lasers) provides them the ability to meet the demands of current biochip technologies. In earlier research, optical trapping of live biological cells and microspheres based on VCSEL array has been realized in the form of parallel static traps on a translation stage. In microfluidic systems (lab-on-a-chip devices), the background flow introduces complexity and uncertainty in velocity and force analysis on target microparticles, making the capability of transporting biological objects without moving sample highly desirable. Moreover independently controllable traps offer more flexibility in microparticle manipulation. In this paper, a microscope-integrated VCSEL trapping system capable of independent control and batch processing of microparticles is devised and demonstrated. Optical design considerations for keeping stable trapping performance while multiplexing are addressed. Both a single optical trap and a trap array can be controlled independently by tilting mirror while their relative depth can be adjusted without power loses in optical system. In the micromanipulator, a single VCSEL trap serves as a collector and distributor, while a VCSEL array provides the carrier for synchronous processing and small range shift. Potential improvement based on two independently controlled VCSEL arrays is discussed and related applications are investigated.
A novel technique is presented which integrates the capacity of a laser tweezer to optically trap and manipulate objects in three-dimensions with the resolution-enhanced imaging capabilities of a solid immersion lens (SIL). Up to now, solid immersion lens imaging systems have relied upon cantilever-mounted SILs that are difficult to integrate into microfluidic systems and require an extra alignment step with external optics. As an alternative to the current
state-of-art, we introduce a device that consists of a free-floating SIL and a laser optical tweezer. In our design, the optical tweezer, created by focusing a laser beam through high numerical aperture microscope objective, acts in a two-fold manner: both as a trapping beam for the positioning and alignment of the SIL and as an near-field scanning beam to image the sample through the SIL. Combining the alignment, positioning, and imaging functions into a single device allows for the direct integration of a high resolution imaging system into microfluidic and biological environments.