1 x 4 InP SOI optical switch replaces passive splitters

Wavelength-division multiplexing (WDM) passive optical network (PON) architectures typically use passive splitters to increase the number of subscribers in a fiberoptic communications system. But unfortunately, users at the same wavelength still need to compete for time-division multiplexing (TDM) time slots, limiting the overall bandwidth of the system. While active optical switches can allow for dynamic bandwidth allocation, PON enclosures are typically located in cabinets where electrical power is not available, ruling out the use of electrically actuated switches. A solution from Eindhoven University of Technology (Eindhoven, The Netherlands) and Ghent University (Ghent, Belgium) is the development of the first bias-free and optically controlled 1 × 4 switch

Optically reconfigurable 1 x 4 remote node switch for access networks

In this paper we demonstrate an optically controlled 1 x 4 remote node switch, based on membrane InP switches bonded to a silicon-on-insulator circuit. We show that the switch exhibits cross talk better than 25 dB between the output ports, and that the switch operates without receiver sensitivity penalty. Furthermore, the proposed switch architecture allows for optical clock distribution as a means to avoid the need for clock recovery at the receiver side. This is demonstrated in a proof-of-principle experiment where data and clock are sent through a single membrane InP switch

Flexible-Robotic Reflector for Aerospace Applications

Existing dish based antennas tend to have geometric morphologic distortion in the surface due to drastic thermal changes common in the space environment. In this paper we present a new concept for a dynamic antenna specially designed for communication satellites. The suggested flexible-robotic antenna is based on a dual-reflector structure, where the subreflector has a complex surface shaping robotic mechanism allowing it to fix most of the morphologic errors in the main reflector. We have implemented a set of searching algorithms allowing the hyper redundant robotic subreflector to adapt its surface to the morphologic distortions in the main reflector. The suggested new antenna was constructed and tested in an RF room in which it was able to fix the loss caused by distortion in the main reflector to the original gain in less than an hour

All-optical wavelength conversion using mode switching in InP microdisc laser

Wavelength conversion using an indium phosphide based microdisc laser (MDL) heterogeneously integrated on a silicon-on-insulator waveguide is reported. Several lasing modes are present within the disc cavity, between which wavelength conversion can be performed by mode switching and spectral filtering. For the first time, low-power wavelength up- and downconversion using one single MDL is demonstrated. Operation with a bit error rate below 10(-9) at 2.5 Gbit/s and operation below the forward-error-correction limit of 10(-3) at 10 Gbit/s are shown without the use of additional seeding beams

Ultrafast and bias-free all-optical wavelength conversion using III-V-on-silicon technology

Using a 7.5 μm diameter disk fabricated with III-V-on-silicon fabrication technology, we demonstrate bias-free all-optical wavelength conversion for non-return-to-zero on–off keyed pseudorandom bit sequence (PRBS) data at the speed of 10 Gbits/s with an extinction ratio of more than 12 dB. The working principle of such a wavelength converter is based on free-carrier-induced refractive index modulation in a pump–probe configuration. We believe it to be the first bias-free on-chip demonstration of all-optical wavelength conversion using PRBS data. All-optical gating measurements in the pump–probe configuration with the same device have revealed that it is possible to achieve wavelength conversion beyond 20 Gbits/s

Retrosternal Percutaneous Tracheostomy: An Approach for Predictably Impossible Classic Tracheostomy

Percutaneous tracheostomy is a routine procedure in intensive care units. In cases of very low position of the larynx, cervical spine deformation, morbid obesity, or neck tumor, performance of the classic tracheostomy is inapplicable. Retrosternal approach to tracheostomy in such 20 patients is herein reported. After preoperative neck computerized tomography to define the neck anatomy, a small suprasternal incision followed by a short retrosternal tissue dissection to expose the trachea was done; the trachea was then catheterized at the level of the 2nd ring in the usual tracheostomy manner. The immediate and late (≥6 months) outcomes were similar to that of the standard tracheostomy. Thus, percutaneous retrosternal tracheostomy is safe in patients with abnormal positioning of the trachea or neck constitution. It is a bedside applicable technique, that, however, requires caution to avoid hazardous vascular complications