Characterisation of patients with endoscopy-negative, computer tomography-negative midfacial segment pain using the sino-nasal outcome test.

BACKGROUND: The purpose of this study was to qualitatively characterise patients with midfacial segment pain (MSP) using the Sino-Nasal Outcome Test (SNOT). The data will provide a detailed overview of the physical and psychological impact on patients'well-being, and how it compares with the normal, healthy population. METHODS: Suitable patients were prospectively identified from the Multi-disciplinary Facial Pain Clinic at the Royal Liverpool University Hospital, based on the diagnostic criteria for MSP. The pre-treatment SNOT-22 of these patients were also compared to patients with chronic rhinosinusitis and normal healthy volunteers. RESULTS: Twenty-nine consecutive patients with a diagnosis of MSP were identified, and compared with 30 CRS patients and 34 healthy volunteers. The average SNOT-22 scores of MSP and CRS patients were higher than normal healthy volunteers. Patients with CRS had the highest rhinological subscale SNOT scores compared to normal healthy volunteers and MSP. Conversely, the reported ear and facial symptoms of MSP patients were most unfavourable. A similar trend was observed in reported sleep function where MSP patients recorded higher subscale scores than the other two cohorts. The subscale mean score for psychological function of MSP patients was not significant when compared to the mean score of patients diagnosed with CRS. CONCLUSION: MSP has an adverse impact on both physical and psychological well-being. The subtle differences in the SNOT subscores between MSP and CRS have provided greater insight into the character and disease impact of MSP. We propose that the SNOT may be suitably utilised in MSP to document disease severity and measure response to treatment.

Stable and wavelength-tunable silicon-micro-ring-resonator based erbium-doped fiber laser.

In this work, we propose and demonstrate a stable and wavelength-tunable erbium-doped fiber (EDF) ring laser. Here, a silicon-on-insulator (SOI)-based silicon-micro-ring-resonator (SMRR) is used as the wavelength selective element inside the fiber ring cavity. A uniform period grating coupler (GC) is used to couple between the SMRR and single mode fiber (SMF) and serves also as a polarization dependent element in the cavity. The output lasing wavelength of the proposed fiber laser can be tuned at a tuning step of 2 nm (defined by the free spectral range (FSR) of the SMRR) in a bandwidth of 35.2 nm (1532.00 to 1567.20 nm), which is defined by the gain of the EDF. The optical-signal-to-noise-ratio (OSNR) of each lasing wavelength is larger than 42.0 dB. In addition, the output stabilities of power and wavelength are also discussed.

Demonstration of bi-directional LED visible light communication using TDD traffic with mitigation of reflection interference.

In this work, we experimentally demonstrate a bi-directional transmission link using light emitting diode (LED) visible light communication (VLC) for both downlink and uplink paths. Time-division-duplex (TDD) is proposed and demonstrated to significantly eliminate the reflection interference in VLC. A free space bi-directional transmission of 2 m using simple on-off keying (OOK) modulation with bit error rate (BER) of < 10(-5) in both directions are achieved. Moreover, the influence of reflection interference is analyzed, showing the proposed scheme can significantly eliminate the reflection interference.

Long-reach radio-over-fiber signal distribution using single-sideband signal generated by a silicon-modulator.

The integration of passive optical network (PON) and radio-over-fiber (ROF) networks could provide broadband services for both fixed and mobile users in a single and low-cost platform. Combining the long-reach (LR)-PON (>100 km) and the LR-ROF can further reduce the cost by simplifying the network architecture, sharing the same optical components and extending the coverage of ROF network. However, the transmission and distribution of ROF signal in LR network is very challenging due to the chromatic dispersion generated periodic power fading and code time-shifting effects in the optical fiber. In this work, we propose and experimentally demonstrate a LR-ROF signal distribution using single-sideband (SSB)-ROF signal generated by a silicon ring-modulator. The silicon modulator is compact and has low power consumption. Besides, one unique feature of the silicon ring-modulator is that it only modulates the signal wavelength at the resonant null. This makes it very suitable for the generation of the SSB-ROF signal. Numerical comparison of the SSB-ROF with the double-sideband (DSB)-ROF and optical carrier suppress (OCS)-ROF signals; as well as the fabrication of the silicon ring-modulator will be discussed.

Dynamic gain-tilt compensation using electronic variable optical attenuators and a thin film filter spectral tilt monitor.

An all-optical dynamic gain tilt compensator (DGTC) is proposed and experimentally demonstrated. A single wide-band thin film filter and a pair of photodetector allow the DGTC to distinguish band add/drop position. Power fluctuations from EDFA gain tilt were reduced with fast electronic variable optical attenuators.

Optical label encoding and swapping using half-bit delayed dark RZ payload and DPSK label.

Orthogonal labeling is a potential candidate in future opticallabel- switched-networks. Half-bit-delayed-dark-return-to-zero (HBDDRZ) payload with DPSK orthogonal labeling is proposed. The precise payload extinction-ratio adjustment at source nodes and maintenance at each intermediate node is not needed. The high extinction-ratio of both payload and label improves the receiver margin. Owing to the RZ-like nature of the demodulated DPSK label, HBDDRZ payload causes negligible effect on the label. Nonlinear-optical-loop-mirror generates the HBDDRZ payload, which is then encoded by DPSK label. Label swapping is demonstrated by birefringence switching. 10-Gb/s bit-error-rate measurements are performed.

Nonlinear absorption and Raman gain in helium-ion-implanted silicon waveguides.

We study whether helium ion implantation can reduce the carrier lifetime and thus reduce the density of two-photon-absorption-generated free carriers. Our experiments and theoretical model show that helium ion implantation into silicon waveguides can successfully reduce the free-carrier losses and allow net gain to be attained by cw-pumped stimulated Raman scattering without requiring reverse bias to remove the photogenerated free carriers.

Optical label switching of DRZ/DPSK orthogonal signal generated by photonic-crystal fiber.

We demonstrate orthogonal label switching by using a dark-return-to-zero (DRZ) payload and differential phase-shift keying (DPSK) label generated by a dispersion-flattened photonic-crystal fiber. The high extinction ratio of both the payload and label improves the receiver margin. The DRZ payload introduces little cross talk to the DPSK label due to the RZ-like output of the demodulated DPSK. Simulations are performed to study the eye-closure penalty of the payload and label at different DRZ pulse widths. We compare the DRZ/DPSK with the RZ and DPSK signals numerically at the same data rate and show that the DRZ/DPSK has a strong tolerance to the polarization-mode dispersion. The DRZ/DPSK has a more compact spectrum suitable for the strong filtering requirements in WDM systems.

Nonlinear polarization rotation in a dispersion-flattened photonic-crystal fiber for ultrawideband (>100 nm) all-optical wavelength conversion of 10 Gbit/s nonreturn-to-zero signals.

We study the conversion bandwidth of the cross-polarization-modulation (XPoIM)-based wavelength conversion scheme with a dispersion-flattened highly nonlinear photonic-crystal fiber for signals with a nonreturn-to-zero (NRZ) modulation format. Both theoretical and experimental results show that the conversion bandwidth can be extended to cover a very wide band, including S-, C-, and L-bands for 10 Gbit/s NRZ signals (a total bandwidth of 120 nm is experimentally demonstrated). We also study the theoretical bandwidth limit for 40 Gbit/s NRZ signals. A significant extension of the conversion bandwidth using the XPoIM approach compared with the four-wave mixing approach previously reported is demonstrated.

Transverse offset loss between two identical noncircular single-mode waveguides.

We derive an approximation for the transverse offset loss based on the Laplacian mode-field half-width (MFHW) and far-field second moment for two arbitrary identical noncircular single-mode waveguides. The relation is reduced to the known result for circular-symmetric, single-mode waveguides. Numerical results for symmetrical rectangular waveguides show that the transverse offset loss calculated from the Laplacian MFHW is more accurate than that from the elliptical Gaussian MFHW for small transverse offsets. To our knowledge, this is the first calculation of the errors in the approximate transverse offset loss relations derived from the Laplacian and the elliptical Gaussian MFHW for noncircular optical waveguides.

Mode conversion and birefringence adjustment by focused-ion-beam etching for slanted rib waveguide walls.

We describe how focused-ion-beam (FIB) etching of slanted rib waveguide walls can be used to modify the differential group delay in a waveguide and introduce TE to TM mode conversion in a silicon-on-insulator rib waveguide. We achieved mode conversion by modifying the geometric cross section of a single-mode rib by FIB trimming. Waveguides with different lengths of 45 degrees slant angle rib waveguide walls were fabricated and characterized. We measured the differential group delays and the mode conversion achieved for waveguides with different lengths of a FIB-trimmed slanted rib wall.

Optical packet labeling based on simultaneous polarization shift keying and amplitude shift keying.

We propose and demonstrate label encoding-swapping and transmission for an orthogonally labeled packet by use of a 10-Gbit/s amplitude shift keying payload and a 2.5-Gbit/s polarization shift keying (PolSK) label. A simple scheme for demodulating and demultiplexing the PolSK label based on an injection-locked Fabry-Perot laser diode is described. The extinction ratio of the newly added PolSK label can be precisely controlled and maintained after the intermediate node.

An effective treatment of comminuted fractures of the distal radius.

One hundred cases of comminuted fracture of the distal radius were treated by a simple uniform method consisting of distraction by an external fixator for 3 weeks followed by functional bracing. During the application of the external fixator, autogenous cancellous bone chips were taken from the iliac crest and packed into the fracture site to realign the juxtaarticular fragments and to fill up the bone gap. Complications have been minimal. The results, after an average follow-up period of 20 months, taking into consideration subjective assessment of pain, objective measurement of wrist motion, and radiologic angles, have been excellent.