Bistability in silicon microring resonator based on strain induced by a piezoelectric lead zirconate titanate thin film

We demonstrate bistability in a submicron silicon optical phase shifter based on the photoelastic effect. The strain magnitude is electrically controlled by a piezoelectric thin film placed on top of the device. The hysteresis behavior of the piezoelectric response shows potential application as bistable device independent of the optical intensity. © 2012 American Institute of Physics.

Ultrathin silicon nitride microring resonator for biophotonic applications at 970 nm wavelength

We experimentally demonstrate a high-Q ultrathin silicon nitride microring resonator operating at wavelength of 970 nm that is favorable for large variety of biophotonic applications. Implementation of thin device layer of 200 nm allows enhanced interaction between the optical mode and environment, while still maintaining high quality factor of resonator. In addition, we show the importance of spectral window around 970 nm to improve device sensing capability. © 2010 American Institute of Physics.

MIMO System capacity improvements using radio-over-fibre distributed antenna system technology

The effect of antenna separation in a 3×3 MIMO system using RoF DAS technology is investigated. Larger antenna separation is found to improve the throughput due to reduced channel correlation and improved SNR. © OSA/OFC/NFOEC 2011.

Experimental investigation of antenna selection and transmit beamforming for capacity enhancement in 3×3 MIMO-enabled radio-over-fiber DAS

This paper examines the impact of two simple precoding schemes on the capacity of 3 × 3 MIMO-enabled radio-over-fiber (RoF) distributed antenna systems (DAS) with excess transmit antennas. Specifically, phase-shift-only transmit beamforming and antenna selection are compared. It is found that for two typical indoor propagation scenarios, both strategies offer double the capacity gain that non-precoding MIMO DAS offers over traditional MIMO collocated antenna systems (CAS), with capacity improvements of 3.2-4.2 bit/s/Hz. Further, antenna selection shows similar performance to phase-only beamforming, differing by <0.5% and offering median capacities of 94 bit/s/Hz and 82 bit/s/Hz in the two propagation scenarios respectively. Because optical DASs enable precise, centralized control of remote antennas, they are well suited for implementing these beamforming schemes. Antenna selection, in particular, is a simple and effective means of increasing MIMO DAS capacity. © 2013 IEEE.

Experimental evaluation of layout designs for 3 × 3 MIMO-enabled radio-over-fiber distributed antenna systems

This paper experimentally demonstrates that, for two representative indoor distributed antenna system (DAS) scenarios, existing radio-over-fiber (RoF) DAS installations can enhance the capacity advantages of broadband 3 × 3 multiple-input-multiple-output (MIMO) radio services without requiring additional fibers or multiplexing schemes. This is true for both single-and multiple-user cases with a single base station and multiple base stations. First, a theoretical example is used to illustrate that there is a negligible improvement in signal-to-noise ratio (SNR) when using a MIMO DAS with all N spatial streams replicated at N RAUs, compared with a MIMO DAS with only one of the N streams replicated at each RAU for N ≤ 4. It is then experimentally confirmed that a 3 × 3 MIMO DAS offers improved capacity and throughput compared with a 3 × 3 MIMO collocated antenna system (CAS) for the single-user case in two typical indoor DAS scenarios, i.e., one with significant line-of-sight (LOS) propagation and the other with entirely non-line-of-sight (NLOS) propagation. The improvement in capacity is 3.2% and 4.1%, respectively. Then, experimental channel measurements confirm that there is a negligible capacity increase in the 3 × 3 configuration with three spatial streams per antenna unit over the 3 × 3 configuration with a single spatial stream per antenna unit. The former layout is observed to provide an increase of ∼1% in the median channel capacity in both the single-and multiple-user scenarios. With 20 users and three base stations, a MIMO DAS using the latter layout offers median aggregate capacities of 259 and 233 bit/s/Hz for the LOS and NLOS scenarios, respectively. It is concluded that DAS installations can further enhance the capacity offered to multiple users by multiple 3 × 3 MIMO-enabled base stations. Further, designing future DAS systems to support broadband 3 × 3 MIMO systems may not require significant upgrades to existing installations for small numbers of spatial streams. © 2013 IEEE.

On-chip tunable micro-ring resonator based on digital microfluidics platform

We demonstrate the tunability of a silicon nitride micro-resonator using the concept of Digital Microfluidics. Our system allows driving micro-droplets on-chip, enabling the control of the effective refractive index at the vicinity of the resonator. © 2010 OSA/FiO/LS 2010.

Ultra-thin silicon nitride microring resonator for biophotonic applications at 970nm wavelength

We experimentally demonstrate an ultra-thin silicon nitride microring resonator operating at wavelength of 970nm that is favorable for large variety of biophotonic applications. Optimization parameters for improved sensitivity and light-mater interaction are presented. © 2010 Optical Society of America.