All-optic scheme for automatic polarization division demultiplexing.

We describe a cost effective scheme to automatically separate two polarization channels in a polarization division multiplexing (PDM) system, without having to modify the existing transmitter or receiver electronics or software. We experimentally validate the concept by achieving an extinction ratio of more than 28-dB between two demultiplexed channels. Finally, we successfully demonstrate the PDM scheme in a 1.

Combination of optical and electronic logic gates for error correction in multipath differential demodulation.

We present an optical multipath error correction technique for differentially encoded modulation formats such as differential-phase-shift-keying (DPSK) and differential polarization shift keying (DPolSK) for fiber-based and free-space communication. This multipath error correction method combines optical and electronic logic gates. The scheme can easily be implemented using commercially available interferometers and high speed logic gates and does not require any data overhead therefore does not affect the effective bandwidth of the transmitted data.

Free spectral range optimization of return-to-zero differential phase shift keyed demodulation in the presence of chromatic dispersion.

Optical differential phase shift keying is normally demodulated in a delay-line interferometer with a 1-bit delay such that the free-spectral-range of the demodulator is equal to the transmitted bitrate. We show using Karkunen-Loeve expansion simulation that free-spectral-range optimization leads to increased chromatic dispersion tolerances. The optimized delay inversely scales with the amount of chromatic dispersion such that a delay slightly shorter than the bit period increases tolerances with no adverse effect on the polarization-mode-dispersion tolerance or frequency offset penalty at the receiver.

Simultaneous optical digital half-subtraction and -addition using SOAs and a PPLN waveguide.

We demonstrate an optical half-subtracter and half-adder module that performs simultaneous bit-wise subtraction and addition of two 5 Gbit/s RZ data streams. We generate Borrow (/X*Y) and Difference/Sum (X plus sign in circleY, or XOR) outputs using cross-gain modulation (XGM) in two parallel SOAs. Taking advantage of the gain saturation inherent to SOAs, we generate two signals, /X*Y, and X*/Y, and combine them using a passive optical coupler to generate the XOR Difference/Sum output.

Slow light on Gbit/s differential-phase-shift-keying signals.

We demonstrate, via simulation and experiment, slowing down of a phase-modulated optical signal. A 10.7-Gb/s NRZ-DPSK signal can be delayed by as much as 42 ps while still achieving error free via broadband SBS-based slow light.

Treatment of Postcraniotomy Tension Pneumocephalus via Endoscopic Closure of the Nasofrontal Recess.

Tension pneumocephalus can be a life-threatening complication following cranial surgery. We report a 14-year-old female who developed tension pneumocephalus following her most recent external approach to a recurrent pilocytic astrocytoma of the skull base and clivus. Because the risk of devascularization of the recently placed bone grafts was a concern, an endoscopic approach was chosen instead of a cramotomy.

Data pulse distortion induced by a slow-light tunable delay line in optical fiber.

We experimentally demonstrate an all-optical tunable delay line based on slow light induced by stimulated Brillouin scattering in a highly nonlinear fiber (HNLF) and study the distortion of data pulses with different pulse widths and the induced pattern-dependent distortion on non-return-to-zero data in slow-light systems.

All-optical half adder using an SOA and a PPLN waveguide for signal processing in optical networks.

We demonstrate an all-optical half adder for bit-wise addition of two serial data streams that simultaneously generates Sum and Carry outputs. The module performs the required XOR and AND operations using only two nonlinear optical elements. Difference Frequency Generation in a periodically poled lithium niobate waveguide serves as the AND gate and cross-gain modulation in a semiconductor optical amplifier is employed to generate the XOR output.

Simultaneous four-wave mixing and cross-gain modulation for implementing an all-optical XNOR logic gate using a single SOA.

We report on an all-optical XNOR-gate using simultaneous Four-Wave Mixing (FWM) and Cross-Gain Modulation (XGM) in a semiconductor optical amplifier (SOA). FWM generates the bitwise AND output corresponding to the two input data streams while XGM is used to generate the NOR output. These two outputs are combined using a coupler to obtain the final XNOR output.

All-optical, wavelength and bandwidth preserving, pulse delay based on parametric wavelength conversion and dispersion.

We demonstrate an all-optical tunable delay in fiber based on wavelength conversion, group-velocity dispersion, and wavelength reconversion. The device operates near 1550 nm and generates delays greater than 800 ps. Our delay technique has the combined advantages of continuous control of a wide range of delays from picoseconds to nanoseconds, for a wide range of signal pulse durations (ps to 10 ns), and an output signal wavelength and bandwidth that are the same as that of the input.

Reach extension in 10-Gb/s directly modulated transmission systems using asymmetric and narrowband optical filtering.

Optical filtering has been used to extend the reach of directly modulated laser in 10Gb/s WDM systems via two separate mechanisms: narrowing the broadened spectrum, and converting frequency modulation into useful amplitude modulation. We investigate in detail, the impact of asymmetric and narrowband optical filtering at the transmitter or receiver. Experimental demonstrations for both shorter distance and long-haul like transmission using optical filtering are performed.

Measurement of the chirp parameter of electro-optic modulators by comparison of the phase between two sidebands.

We propose and demonstrate a simple technique for the measurement of the magnitude and sign of the chirp parameter of electro-optic modulators, using phase comparison between two optically filtered vestigial sidebands generated from 10-GHz sinusoidal signals. We show the analytical, simulation, and experimental results of this approach.

Major and minor temporal bone abnormalities in children with and without congenital sensorineural hearing loss.

Objective: To determine the extent of correlation between sensorineural hearing loss (SNHL) and abnormal temporal bone anatomy in children.

Design: Axial and coronal high-resolution computed tomographic scans of the temporal bones of 247 children (494 ears) aged 2 months to 15 years with and without SNHL were blindly reviewed. The presence or absence of mild or severe cochlear dysplasias, vestibular dysplasias, and an enlarged vestibular aqueduct (VA) were recorded.

Tracheal stenosis and congenital heart disease in patients with Down syndrome: diagnostic approach and surgical options.

Upper airway obstruction is a prevalent feature in patients with Down syndrome. However, these patients may be completely asymptomatic in the early months of life. The recognition of a problem within the airway quite often occurs when these children present for cardiac surgery, diagnostic radiography with sedation, or during the induction and intubation for anesthesia.

Extraluminal laryngotracheal fixation with absorbable miniplates.

Objective: To determine if miniplates made of polydioxanone can be used successfully for extraluminal laryngotracheal fixation.

Design: Twelve rabbits underwent anterior and posterior laryngotracheofissure with extraluminal fixation of the divided segments with polydioxanone miniplates. Three control animals did not undergo plating.

Rib-muscle pedicle flap for the repair of congenital tracheal stenosis.

Congenital tracheal stenosis (CTS) is an uncommon congenital anomaly that presents early in life with symptoms of biphasic stridor. Most cases require surgical correction. Techniques have included dilation, resection of the involved segment, and tracheoplasty.

Reconstruction of the pediatric airway with an open stented tracheotomy tube.

Reconstructive techniques for the stenotic pediatric airway have greatly enhanced the otolaryngologists ability to decannulate the tracheotomy-dependent child. Stents have played an important role in this process by both maintaining the reconstructed lumen and acting as a scaffold. However, decannulation is often not achieved after the first surgical intervention with some patients requiring two, three or more procedures.

Auricular injury as a presentation of child abuse.

Child abuse causes serious physical and emotional injury. Those abused, however, are usually unable or unwilling to gain access to agencies that might help them. The otolaryngologist, while usually not the patient's primary physician, may be in the position to detect child abuse.

An enteric duplication cyst occurring in the anterior two-thirds of the tongue.

Enteric duplication cysts are cysts that are attached to the alimentary tract and that are lined by some type of gastrointestinal mucosa. Such cysts are especially rare when found in the oral cavity. We report the case of an 8-month-old female with an unusual duplication cyst in the anterior two-thirds of the tongue.

Modeling of riblike waveguides with isolation trenches of finite width.

A method for calculating the propagation and loss characteristics of riblike waveguiding structures having isolation trenches of finite width is presented.

Interpersonal style and personality deviation.

Forensic psychiatric patients were assigned to empirically derived categories of personality deviation, and described their interpersonal reactions in situations of threat and affiliation. Differences between groups were maintained across situations, and support the utility of conceptualizing personality disorders in terms of inflexible interpersonal styles.