Optical Ports Research Articles

Thoracoscopic Rib Resection in Children.

The authors present a multicenter retrospective series of different benign rib lesions in children operated on using thoracoscopy. Between 2005 and 2015, 17 rib resections were performed thoracoscopically, in four French departments of pediatric surgery. Of these 17 cases, 13 exostoses, 2 endochondromas, 1 synostosis, and 1 Cyriax's syndrome were noted. Inclusion criteria were benign tumors or rib anomalies such as synostosis, in children younger than the age of 18 years, and thoracoscopy. Open surgery and malignant tumors were excluded. Thoracoscopy was put forward using one optical port as well as one or two operative ports. Ten patients presented with chest pain, dyspnea, or unexplained cough. Six tumors were incidentally diagnosed. One patient presented with a chest wall deformation. Single-lung ventilation was required in 2 cases. In 1 case of endochondroma, a segmental rib resection was performed, leaving a part of the periosteum and the intercostal vessels and nerve. In this case, rib resection was performed using an endoscopic shaver drill system. As for the other cases, a simple resection of the tumor or of the bridge between two ribs (synostosis) was performed. In these cases, a Codman Kerrison laminectomy rongeur was used. There was no complication during or after surgery. Nevertheless, 2 years after surgery, pain did not disappear in 1 case, probably due to a definitive intercostal nerve damage. Benign rib lesions in children are rare. Thoracoscopy may be offered to reduce the functional deleterious consequences of an open surgery. It may be put forward especially in case of hereditary multiple exostoses where redo procedures may be required.

Laparoscopic ventral hernia repair using only 5-mm ports.

The technique of laparoscopic ventral hernia repair has been evolving since it was first described over 20 years ago. We report a new technique where polyester mesh was back loaded through a 5-mm port site, coming into contact with the skin. This avoids the need for any 10-12-mm ports. A prospective database of laparoscopic ventral hernia repairs was examined. A single surgeon performed 344 laparoscopic ventral hernia repairs using this technique over 60 months. Follow-up was conducted by both clinical and independent phone review. Laparoscopic access was achieved via a 5-mm optical port, adding two, or occasionally three, 5-mm extra ports. Hernia contents were reduced and the extra-peritoneal fat excised; 5-mm tooth graspers were placed through the lateral port and then in a retrograde fashion through the uppermost port. The port was removed, and the mesh pulled back into the abdominal cavity and positioned with a minimum of 3-cm overlap. The mesh was fixed using absorbable tacks and sutures. Most patients had primary umbilical hernias. There was one case of mesh infection due to enteric organisms. This occurred in a patient undergoing repair of a stoma site hernia, resulting from a Hartmann's procedure for perforated diverticulitis. There was no other evidence of acute or chronic mesh infection despite cutaneous contact with the mesh. In this series, there was an overall hernia recurrence rate of 2.4%. Laparoscopic ventral hernia repair using only 5-mm ports is a safe, effective technique with no extra risk of infection.

Responsivity Enhancement of Metal-Insulator-Semiconductor Photodetectors on Silicon-on-Insulator Substrates by Plasmonic Nanoantennas

We report metal-insulator-semiconductor photodetectors fabricated on a silicon-on-insulator substrate, exhibiting an enhanced responsivity in the near-infrared due to the incorporation of Au-nanoantennas at the optical input port. The optimal antenna design and the photoresponse enhancements have been calculated using detailed finite-difference time-domain simulations. These nanoantennas modify the propagation of the input optical signals. In this regime, strong plasmonic local field enhancements are observed. The maximum responsivity enhancement, 40%, was obtained at 780 nm; while at wavelengths shorter than 720 nm, the responsivity is reduced due to absorption losses in the Au-nanoantennas.

Recording Spikes Activity in Cultured Hippocampal Neurons Using Flexible or Transparent Graphene Transistors.

The emergence of nanoelectronics applied to neural interfaces has started few decades ago, and aims to provide new tools for replacing or restoring disabled functions of the nervous systems as well as further understanding the evolution of such complex organization. As the same time, graphene and other 2D materials have offered new possibilities for integrating micro and nano-devices on flexible, transparent, and biocompatible substrates, promising for bio and neuro-electronics. In addition to many bio-suitable features of graphene interface, such as, chemical inertness and anti-corrosive properties, its optical transparency enables multimodal approach of neuronal based systems, the electrical layer being compatible with additional microfluidics and optical manipulation ports. The convergence of these fields will provide a next generation of neural interfaces for the reliable detection of single spike and record with high fidelity activity patterns of neural networks. Here, we report on the fabrication of graphene field effect transistors (G-FETs) on various substrates (silicon, sapphire, glass coverslips, and polyimide deposited onto Si/SiO2 substrates), exhibiting high sensitivity (4 mS/V, close to the Dirac point at VLG < VD) and low noise level (10−22 A2/Hz, at VLG = 0 V). We demonstrate the in vitro detection of the spontaneous activity of hippocampal neurons in-situ-grown on top of the graphene sensors during several weeks in a millimeter size PDMS fluidics chamber (8 mm wide). These results provide an advance toward the realization of biocompatible devices for reliable and high spatio-temporal sensing of neuronal activity for both in vitro and in vivo applications.

Новий безпечний спосіб введення першого (оптичного) порту при виконанні симультанних комбінованих операцій при поєднанні симптомної жовчнокам’яної хвороби та лівобічної пахової грижі

Мета роботи: описати новий безпечний спосіб введення першого (оптичного) порту при виконанні симультанних операцій з приводу жовчнокам’яної хвороби (ЖКХ) та лівобічної пахової грижі.Суть методу полягає у виконанні комбінованого операційного втручання, яке розпочинається з герніотомії пахової грижі, виділення грижового мішка. Наступним етапом операції є введення в черевну порожнину першого (оптичного) троакара через мішок грижі. Останній зав’язується лігатурою на оптичному порті для герметизації черевної порожнини та накладанням пневмоперитонеуму. Лапароскопічна холецистектомія виконується після введення 2–4-го портів у типових точках. Жовчний міхур видаляться через мішок пахової грижі. Після резекції мішка проводиться герніопластика. Вказаний спосіб дозволяє абсолютно безпечно накласти пневмоперитонеум, видалити жовчний міхур без розширення розрізу навіть при великих розмірах жовчних конкрементів та значно скоротити час виконання двох одночасних операцій.

Demonstration of a 3 × 4 tunable bandwidth WSS with tunable attenuation using compact spatial light paths.

M × N wavelength selective switch (WSS) is a core component to address wavelength conflict in an optical switching node. In this paper, we design and experimentally demonstrate a performance enhanced 3 × 4 tunable bandwidth WSS (TBWSS) with tunable attenuation across the full C-band, and using compact spatial light paths. Wavelength channels from any input optical fiber port can be switched into any output optical fiber port with best insertion loss (IL) of 8.4 dB and worst IL of 12.5 dB. The attenuation tuning range can reach up to 35 dB. Compared to previous demonstrations, more than 2 dB IL improvement is achieved. Based on the proposed compact spatial light paths, the number of input and output ports can be easily extended to 10 and 20, respectively.

Postprocessing Phase Stabilizer for Wide Frequency Range Photonic-Microwave Signal Distribution

In the field of leading-edge techniques, such as broadband communications and large-scale radio interferometer applications, the need for a highly stable/wide-frequency-range photonic-microwave signal (continuous sine wave) is increasing. The main purpose of this research is to provide a highly stable photonic-microwave signal over a large broadband from microwave to terahertz frequencies using the same optical signal generation/transmission system. While transmitting signals through an optical cable, the transmission delay fluctuates and it suffers from chromatic dispersion that affects the distribution signal coherence. We have developed a postprocessing scheme transmission phase stabilizer. In the scheme, the measured phase of the round-tripped signal is acquired at time intervals at the optical transmitting port (an optical input port), and then the measured phase data are sent to the destination port (an optical output port) for the transmission phase compensation. The postprocessing method has advantages for a frequency dynamic range and compensation range issue. Theoretically, there is no upper frequency limit on the proposed phase stabilizer. We also discuss a high-frequency signal generator based on an optical comb signal generator up to terahertz frequencies.

Experimental setup for the laboratory investigation of micrometeoroid ablation using a dust accelerator.

A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles' path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

Ultrafast electron microscopy: Instrument response from the single-electron to high bunch-charge regimes

We determine the instrument response of an ultrafast electron microscope equipped with a conventional thermionic electron gun and absent modifications beyond the optical ports. Using flat, graphite-encircled LaB6 cathodes, we image space-charge effects as a function of photoelectron-packet population and find that an applied Wehnelt bias has a negligible effect on the threshold levels (>103 electrons per pulse) but does appear to suppress blurring at the upper limits (∼105 electrons). Using plasma lensing, we determine the instrument-response time for 700-fs laser pulses and find that single-electron packets are laser limited (1ps), while broadening occurs well below the space-charge limit.

Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H2O, CO2, CO, and temperature in combustion flows.

The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H2O, CO2, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H2O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO2 and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H2O, 0.6% CO2, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

A Novel Approach to Photonic Packaging Leveraging Existing High-Throughput Microelectronic Facilities

Silicon photonics leverages microelectronic fabrication facilities to achieve photonic circuits of unprecedented complexity and cost efficiency. This efficiency does not yet translate to optical packaging, however, which has not evolved substantially from legacy devices. To reach the potential of silicon photonics, we argue that disruptive advances in the packaging cost, scalability in the optical port count, and scalability in the manufacturing volume are required. To attain these, we establish a novel photonic packaging direction based on leveraging existing microelectronics packaging facilities. We demonstrate two approaches to fiber-to-chip interfacing and one to hybrid photonic integration involving direct flip-chip assembly of photonic dies. Self-alignment is used throughout to compensate for insufficient placement accuracy of high-throughput pick and place tools. We show a self-aligned peak transmission of -1.3 dB from standard cleaved fibers to chip and of -1.1 dB from chip to chip. The demonstrated approaches are meant to be universal by simultaneously allowing wide spectral bandwidth for coarse wavelength division multiplexing and large optical-port count.

DSMC analysis of bipropellant thruster plume impingement on a geostationary spacecraft

To quantify the potential contamination induced by exhaust plume from the MBB 10 N bipropellant thruster firing, we performed plume impingement analyses on the sensitive surfaces. The heat and mass fluxes of chemical species on the spacecraft surfaces and on the specific area of sensor units (optical port and radiator) were evaluated. A fully unstructured three-dimensional Direct simulation Monte Carlo (DSMC) code was developed and validated with measurements. A geostationary satellite with an optical port and radiator was selected and the actual configuration of the satellite was simplified by considering a bipropellant thruster, which is a major plume source to the sensitive surfaces, two communication antennas, and satellite panels. The DSMC computations show that the mass distribution or plume gas composition is unevenly distributed due to the mass separation effect, which occurs from the rapid expansion into vacuum especially around the nozzle lip at the backflow region. H2O is known as the most critical contaminant species; however, its plume impingement effect on the sensitive surfaces is negligible compared to the evaporation rate calculated by Langmuir’s evaporation equation. Not only have the results contributed to the geostationary satellite development, but also these findings are expected to be significant in designing spacecraft configurations and useful in the trade-off studies.

An electrical probe of the phonon mean-free path spectrum.

Most studies of the mean-free path accumulation function (MFPAF) rely on optical techniques to probe heat transfer at length scales on the order of the phonon mean-free path. In this paper, we propose and implement a purely electrical probe of the MFPAF that relies on photo-lithographically defined heater-thermometer separation to set the length scale. An important advantage of the proposed technique is its insensitivity to the thermal interfacial impedance and its compatibility with a large array of temperature-controlled chambers that lack optical ports. Detailed analysis of the experimental data based on the enhanced Fourier law (EFL) demonstrates that heat-carrying phonons in gallium arsenide have a much wider mean-free path spectrum than originally thought.

OAM-labeled free-space optical flow routing.

Space-division multiplexing allows unprecedented scaling of bandwidth density for optical communication. Routing spatial channels among transmission ports is critical for future scalable optical network, however, there is still no characteristic parameter to label the overlapped optical carriers. Here we propose a free-space optical flow routing (OFR) scheme by using optical orbital angular moment (OAM) states to label optical flows and simultaneously steer each flow according to their OAM states. With an OAM multiplexer and a reconfigurable OAM demultiplexer, massive individual optical flows can be routed to the demanded optical ports. In the routing process, the OAM beams act as data carriers at the same time their topological charges act as each carrier's labels. Using this scheme, we experimentally demonstrate switching, multicasting and filtering network functions by simultaneously steer 10 input optical flows on demand to 10 output ports. The demonstration of data-carrying OFR with nonreturn-to-zero signals shows that this process enables synchronous processing of massive spatial channels and flexible optical network.

A multiport MR-compatible neuroendoscope: spanning the gap between rigid and flexible scopes.

OBJECTIVE Rigid endoscopes enable minimally invasive access to the ventricular system; however, the operative field is limited to the instrument tip, necessitating rotation of the entire instrument and causing consequent tissue compression while reaching around corners. Although flexible endoscopes offer tip steerability to address this limitation, they are more difficult to control and provide fewer and smaller working channels. A middle ground between these instruments-a rigid endoscope that possesses multiple instrument ports (for example, one at the tip and one on the side)-is proposed in this article, and a prototype device is evaluated in the context of a third ventricular colloid cyst resection combined with septostomy. METHODS A prototype neuroendoscope was designed and fabricated to include 2 optical ports, one located at the instrument tip and one located laterally. Each optical port includes its own complementary metal-oxide semiconductor (CMOS) chip camera, light-emitting diode (LED) illumination, and working channels. The tip port incorporates a clear silicone optical window that provides 2 additional features. First, for enhanced safety during tool insertion, instruments can be initially seen inside the window before they extend from the scope tip. Second, the compliant tip can be pressed against tissue to enable visualization even in a blood-filled field. These capabilities were tested in fresh porcine brains. The image quality of the multiport endoscope was evaluated using test targets positioned at clinically relevant distances from each imaging port, comparing it with those of clinical rigid and flexible neuroendoscopes. Human cadaver testing was used to demonstrate third ventricular colloid cyst phantom resection through the tip port and a septostomy performed through the lateral port. To extend its utility in the treatment of periventricular tumors using MR-guided laser therapy, the device was designed to be MR compatible. Its functionality and compatibility inside a 3-T clinical scanner were also tested in a brain from a freshly euthanized female pig. RESULTS Testing in porcine brains confirmed the multiport endoscope's ability to visualize tissue in a blood-filled field and to operate inside a 3-T MRI scanner. Cadaver testing confirmed the device's utility in operating through both of its ports and performing combined third ventricular colloid cyst resection and septostomy with an endoscope rotation of less than 5°. CONCLUSIONS The proposed design provides freedom in selecting both the number and orientation of imaging and instrument ports, which can be customized for each ventricular pathological entity. The lightweight, easily manipulated device can provide added steerability while reducing the potential for the serious brain distortion that happens with rigid endoscope navigation. This capability would be particularly valuable in treating hydrocephalus, both primary and secondary (due to tumors, cysts, and so forth). Magnetic resonance compatibility can aid in endoscope-assisted ventricular aqueductal plasty and stenting, the management of multiloculated complex hydrocephalus, and postinflammatory hydrocephalus in which scarring obscures the ventricular anatomy.

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier

Tunable diode laser absorption spectroscopy (TDLAS) was used to measure several important process parameters at two different locations inside the reactor of an atmospheric, air-blown 0.1MWth biomass gasifier. Direct TDLAS at 2298nm was employed for carbon monoxide (CO) and water vapor (H2O), calibration-free scanned wavelength modulation spectroscopy at 1398nm for H2O and gas temperature, and direct TDLAS at 770nm for gaseous elemental potassium, K(g), under optically thick conditions. These constitute the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification, respectively. In addition, soot volume fractions were determined at all TDLAS wavelengths, and employing fixed-wavelength laser extinction at 639nm. Issues concerning the determination of the actual optical path length, as well as temperature and species non-uniformities along the line-of-sight are addressed. During a 2-day measurement campaign, peat and stem wood powder were first combusted at an air equivalence ratio (lambda) of 1.2 and then gasified at lambdas of 0.7, 0.6, 0.5, 0.4 and 0.35. Compared to uncorrected thermocouple measurements in the gas stream, actual average temperatures in the reactor core were significantly higher. The CO concentrations at the lower optical access port were comparable to those obtained by gas chromatography at the exhaust. In gasification mode, similar H2O values were obtained by the two different TDLAS instruments. The measured K(g) concentrations were compared to equilibrium calculations. Overall, the reaction time was found to be faster for peat than for stem wood. All sensors showed good performance even in the presence of high soot concentrations, and real-time detection was useful in resolving fast, transient behaviors, such as changes in stoichiometry. Practical implications of in-situ TDLAS monitoring on the understanding and control of gasification processes are discussed.

Design and development of a portable bit-error rate tester with low cost for any rate between 10 Mb/s and 11.3 Gb/s

The bit-error rate (BER) is an important specification for characterizing the reliability of a communication network link. Aiming at the passive optical access network and wireless broadband access network with the multi-rate levels and the high cost of operation and maintenance, a low cost and portable bit-error rate tester (BERT) with both optical and electrical ports, and operational rates between 10Mb/s and 11.3Gb/s, is designed and developed in this paper, which consists of a pseudo random binary sequence (PRBS) generator, an error detector (ED), a microcontroller unit (MCU) and a small form-factor pluggable optical transceiver. The test results reveals the generated PRBS has the characteristics of high stability and low jitter and the error counter is accurate for a variety of communication protocols.

Timing measurement and simulation of the activation process in gigabit passive optical networks

The passive optical networks are widely used nowadays. Service providers have many customers in their distribution networks. The most important thing for communication between the end unit and the control unit is an establishment contact. Design and measurement of the activation process between optical network unit and optical line termination is presented. In general, the service providers have a big split ratio (up to 1:128) due to the connection eminent value of the customers per optical line termination port in chassis. We present the simulation of the connection process for 16, 32, 64, and 128 optical network units and the measurement for single optical network unit (the GPON Xpert is able to read a single connection process). We compare our results in simulation discussion.

Bilateral Duplicated Patent Processus Vaginalis Found in Pediatric Laparoscopic Inguinal Hernia Repair

Background: Indirect inguinal hernias are fundamentally the result of failure of closure of the processus vaginalis (PPV). In the laparoscopic era, there have been many reports describing the internal view of inguinal hernias and contralateral patent PPV. However, there has been no report of describing a duplicated patent PPV. Objective: This report describes an anatomical variant of the internal ring in a child diagnosed with a bilateral duplicated PPV who presented with a right-side indirect inguinal hernia. Case: A 16-month-old male presented with an incarcerated right inguinal hernia. Manual reduction was effective, and 2 days later, laparoscopic hernia repair was performed. Under general anesthesia, a 5-mm optical port was inserted into the abdomen and a 30° 5-mm camera was introduced. The other two 3-mm instruments were placed along the lateral border of the rectus muscle. In the laparoscopic view, the edematous and thickened internal ring was found showing evidence of incarceration on the right side. Another hole was found close to the internal ring, which had the same direction and a shared wall of the inguinal canal. On the contralateral side, there was also a duplicated patent PPV. For hernia repair, the right-side internal ring was completely divided at the internal ring level and ligated intracorporeally. The duplicated PPV on the contralateral side was also repaired using the same method. Results: The operative time was 28 minutes and there were no complications. The patient was followed up for 24 months, during which time, there was no recurrence. Conclusions: Laparoscopic hernia repair in children has the additional benefit of enabling the accurate diagnosis of a hernia and the detection of any unexpected anatomical variants. No competing financial interests exist. Runtime of video: 3 mins 23 secs

Optical HMI with biomechanical energy harvesters integrated in textile supports

This paper reports the design, prototyping and experimental validation of a human-machine interface (HMI), named GoldFinger, integrated into a glove with energy harvesting from fingers motion. The device is addressed to medical applications, design tools, virtual reality field and to industrial applications where the interaction with machines is restricted by safety procedures. The HMI prototype includes four piezoelectric transducers applied to the fingers backside at PIP (proximal inter-phalangeal) joints, electric wires embedded in the fabric connecting the transducers, aluminum case for the electronics, wearable switch made with conductive fabrics to turn the communication channel on and off, and a LED. The electronic circuit used to manage the power and to control the light emitter includes a diodes bridge, leveling capacitors, storage battery and switch made by conductive fabric. The communication with the machine is managed by dedicated software, which includes the user interface, the optical tracking, and the continuous updating of the machine microcontroller. The energetic benefit of energy harvester on the battery lifetime is inversely proportional to the activation time of the optical emitter. In most applications, the optical port is active for 1 to 5% of the time, corresponding to battery lifetime increasing between about 14% and 70%.