R-Dex Systems (United States)

We demonstrate optical ranging through turbid underwater medium using a structured beam. This beam consists of two Bessel modes, each carrying a pair of orbital angular momentum order and longitudinal wavenumber. As a result, the beam has a "petal-like" intensity profile with different rotation angles at different distances. The object's distance (z) is retrieved by measuring the rotation angle of the petal-like profile of the back-reflected beam. We demonstrate ⪅ 20-mm ranging errors through scattering with extinction coefficient γ up to 9.4 m^-1 from z = 0 to 0.4 m. We further experimentally demonstrate the enhancement of ranging accuracy using multiple (⪆2) Bessel modes. With the number of modes increasing from two to eight, the average error decreases from approximately 16 mm to approximately 3 mm for a Υ of 5 m^-1. Moreover, we simulate both coarse- and fine-ranging by using two different structured beams. One beam has a slower rotating petal-like profile, leading to a 4X larger dynamic range for coarse ranging. A second beam has a faster rotating profile, resulting in higher accuracy for fine ranging. In our simulation, ⪅ 7-mm errors over a 2-m dynamic range are achieved under 𝛾 = 4 m^-1 .

Utilizing technology derived from a combination of modulated backscatter and FMCW radar, a simple low cost and highly accurate means to report and track the orientation of a tagged structure is reported. The system is comprised of a pair of closely spaced 24 GHz RFID tags interrogated by an FMCW radar and uses a method of phase difference to infer the orientation of the tagged structure. The result is an ultra sensitive, low cost orientation detection system suitable for use in human activity recognition and motion capture applications.

We utilize aperture diversity combined with multiple-mode receivers and multiple-input-multiple-output (MIMO) digital signal processing (DSP) to demonstrate enhanced tolerance to atmospheric turbulence and spatial misalignment in a 10 Gbit/s quadrature-phase-shift-keyed (QPSK) free-space optical (FSO) link. Turbulence and misalignment could cause power coupling from the fundamental Gaussian mode into higher-order modes. Therefore, we detect power from multiple modes and use MIMO DSP to enhance the recovery of the original data. In our approach, (a) each of multiple transmitter apertures transmits a single fundamental Gaussian beam carrying the same data stream, (b) each of multiple receiver apertures detects the signals that are coupled from the fundamental Gaussian beams to multiple orbital angular momentum (OAM) modes, and (c) MIMO DSP is used to recover the data over multiple modes and receivers. Our simulation shows that the outage probability could be reduced from >0.1 to <0.01. Moreover, we experimentally demonstrate the scheme by transmitting two fundamental Gaussian beams carrying the same data stream and recovering the signals on OAM modes 0 and +1 at each receiver aperture. We measure an up to ∼10dB power-penalty reduction for a bit error rate (BER) at the 7% forward error correction limit for a 10 Gbit/s QPSK signal.

We experimentally demonstrate the mitigation of atmospheric turbulence effects using pre-channel combining phase patterns in both uni- and bi-directional free-space 200-Gbit/s orbital angular momentum multiplexed optical links. The inter-channel crosstalk is reduced by up to 18-dB.

Skilled nursing facilities and nursing homes are care settings that offer increasing opportunities for pharmacists to take the lead when addressing the new updated Centers for Medicare and Medicaid Services (CMS) requirements coupled with enhanced quality measures reporting. In addition, the complexity of the medication-related needs and comorbidities of the patients served in long-term care facilities promotes pharmacists practicing to the top of their license. Medication stewardship needs to be an interdisciplinary team activity led by the pharmacist. This article highlights areas of opportunity and innovation focusing on the four areas that reflect new regulations and enhanced scrutiny by CMS: psychotropic medications, transitions in care, antibiotic stewardship, and pain management.

In this Letter, we experimentally demonstrate beaconless beam displacement tracking for free-space optical communication link multiplexing multiple orbital angular momentum (OAM) beams, where the data-carrying OAM beams are used for position detection. 400 Gbit/s data transmission is demonstrated under emulated lateral displacement of up to ±10 mm with power penalties of less than 3dB for all channels. Channel crosstalk is reduced by the beam tracking system to below -18 dB. Moreover, we investigate using a Gaussian beacon for beam displacement tracking, and achieve similar channel crosstalk and power penalties, compared with using the beaconless beam tracking.

We experimentally demonstrate and investigate the performance of a multi-input-multiple-output (MIMO) free-space optical link employing orbital-angular-momentum multiplexing through turbulent channel. We show that turbulence effects can be mitigated by exploiting spatial diversity and MIMO equalization.

The capacity of free-space optical (FSO) communication links could potentially be increased by the simultaneous transmission of multiple orbital angular momentum (OAM) beams. For such an OAM multiplexing approach, one requires the collection of adequate power as well as proportion of the phase front for a system with minimal crosstalk. Here we study the design considerations for an OAM-multiplexed free-space data link, analyzing the power loss, channel crosstalk, and power penalty of the link in the case of limited-size receiver apertures and misalignment between the transmitter and the receiver. We describe the trade-offs for different transmitted beam sizes, receiver aperture sizes, and mode spacing of the transmitted OAM beams under given lateral displacements or receiver angular errors. Through simulations and some experiments, we show that (1) a system with a larger transmitted beam size and a larger receiver aperture is more tolerant to lateral displacement but less tolerant to the receiver angular error, and (2) a system with a larger mode spacing, which uses larger OAM charges, suffers more system power loss but less channel crosstalk; thus, a system with a small mode spacing shows a lower system power penalty when system power loss dominates (e.g., a small lateral displacement or receiver angular error), whereas that with a larger mode spacing shows a lower power penalty when channel crosstalk dominates (e.g., a larger lateral displacement or receiver angular error). This work could be beneficial to the practical implementation of OAM-multiplexed FSO links.