Integrated multi-wavelength lasers : a design study

Multi-wavelength lasers (MWLs) play an important role in wavelength division multiplexing networks, and also in photonic radar beam steering applications. In this paper we study different options for realizing such lasers, monolithically integrated with radio frequency (RF) modulators that can be modulated up to 40 GHz. Configurations of arrayed waveguide grating (AWG)-based MWLs integrated with Mach-Zehnder modulators are discussed. Depending on the application, they can have spatially separated modulated outputs or the modulated signals can be multiplexed onto a common output. A novel configuration, that exploits the reflection and transmission properties of on-chip reflectors is presented.

A model for the operation of perovskite based hybrid solar cells:formation, analysis and comparison to experiment

This work is concerned with the modeling of perovskite based hybrid solar cells formed by sandwiching a slab of organic lead halide perovskite (CH3NH3PbI3?xClx) photo-absorber between (n-type) acceptor and (p-type) donor materials—typically titanium dioxide and spiro. A model for the electrical behavior of these cells is formulated based on drift-diffusion equations for the motion of the charge carriers and Poisson’s equation for the electric potential. It is closed by (i) internal interface conditions accounting for charge recombination/generation and jumps in charge carrier densities arising from differences in the electron affinity/ionization potential between the materials and (ii) ohmic boundary conditions on the contacts. The model is analyzed by using a combination of asymptotic and numerical techniques. This leads to an approximate—yet highly accurate—expression for the current-voltage relationship as a function of the solar induced photo- current. In addition, we show that this approximate current-voltage relation can be interpreted as an equivalent circuit model consisting of three diodes, a resistor, and a current source. For sufficiently small biases the device’s behavior is diodic and the current is limited by the recombination at the internal interfaces, whereas for sufficiently large biases the device acts like a resistor and the current is dictated by the ohmic dissipation in the acceptor and donor. The results of the model are also compared to experimental current-voltage curves, and good agreement is shown

Reversal of Hartmann's procedure after perforated diverticulitis through the stomal side without additional incisions: The SIR procedure

Aims: Reversal of Hartmann's procedure (HP) is a complex operation and only performed in 50-60% of the patients. Stomal incision reversal (SIR), a new minimally invasive procedure for HP reversal, was assessed and compared to the standard surgical approach. Methods: 16 patients who had undergone HP for perforated diverticulitis underwent HP reversal by SIR. The only incision in SIR is the one to release the end colostomy. Intra-abdominal adhesiolysis is done manually. A stapled end-to-end colorectal anastomosis is created. The 16 patients who underwent SIR were compared with 32 control patients who were matched according to gender, age, American Society of Anesthesiologists (ASA) classification and Hinchey stage. Results: The operation time was shorter after SIR than after reversal by laparotomy [75 min (58-208) vs. 141 min (85-276); p < 0.001]. Patients after SIR had a shorter hospital stay than patients after laparotomy [4 days (2-22) vs. 9 days (4-64); p < 0.001]. The numbers of total postoperative surgical complications (early and late) were not different (p = 0.13). The anastomotic leakage rate was similar in both groups (6%). The conversion rate in the SIR group was 19% (n = 3). Conclusion: SIR compared favorably with HP reversal by laparotomy in terms of operation time and hospital stay, without increasing the number of postoperative complications. Copyrigh

Measurements on an autonomous wireless payload at 635 km distance using a sensitive radio telescope

The Delfi-C3 spacecraft carries the first autonomous wireless payload in space. This payload is a wireless sun sensor developed by TNO in the Netherlands. The data captured by the sensor is wirelessly transported to the central computer system inside the spacecraft. Since no additional power supply is needed, this sensor is fully autonomous. The radio link is a FSK link at 915 MHz using a standard Nordic Chipset. At the Delfi C3 spacecraft two of these autonomous sun sensors are mounted. Unfortunately only one is operational. Using the Westerbork Synthesis Radio Telescope we tried to detect the 915 MHz signal from the sun sensor to the internal receiver. Before the measurements could be done, the effects of the shielding of the spacecraft case were measured using a spare spacecraft. The final obtained link budget showed a 10 dB SNR when using a 25 meter single dish telescope. Measurements were performed at the WSRT by using multiple radio telescopes placed in the orbit direction. The downlink signal of Delfi C3 was detected, but the 915 MHz signal was not as it should be. We conclude that the sun sensor is malfunctioning

Design of integrated optics all-optical label swappers for spectral amplitude code label swapping optical packet networks on active/passive InP technology

In this paper the designs of optical label swapper devices, for spectral amplitude coded labels, monolithically integrated on InP active/passive technology are pre sented. The devices are based on cross-gain modulation in a semiconductor optical amplifier. Multi-wavelength operation is enabled by means of arrayed waveguide gratings and ring resonators

Integrated filtered-feedback tunable laser with enhanced control of feedback phase

Recently we presented a novel discretely tunable laser that consists of a Fabry-Perot laser which was forced to operate in single-mode condition by applying on-chip filtered feedback. The laser switches extremely fast (3 ns) and requires simple on/off control currents to switch the wavelength. In these first devices it was not possible to control the phase of the feedback light independently from the feedback intensity. In was solved by adding an extra electrode allowing us to control the phase separately. In this paper we present the new device and study the effect of the control ofthefeedbackphase in order to improve the performance ofthe original tunable laser concept

Monolithically integrated continuously tunable InP-based quantum-dot laser source in the 1.6 to 1.8μm wavelength region

We present our first experimental results of a monolithically integrated continuously tunable laser source for optical coherence tomography in the 1.6 to 1.8pm wavelength region. The InP-based active-passive integrated ring laser system contains three 8mm long InAs/InP(1 00) quantum-dot ampl~Iers and two electro-optically tunable filters. Initial results show a tuning range of at least 20nm, 25dB side mode suppression and a linewidth better than 0. 05nm. We present details on the calibration andperformance of the tuningfilters in the laser

AWG-DBR-based WDM transmitter fabricated in an InP generic foundry platform

We report a novel narrow-linewidth WDM transmitter operating at 10 Gbps per transmission channel with 275 kHz optical linewidth. The device, which integrates an AWG-based laser using selective DBR-mirrors with a Mach-Zehnder modulator array, has been fabricated in a multi-project wafer run in a generic InP-based foundry process.</p

Indium phosphide based membrane photodetector for optical interconnects on silicon

We have designed, fabricated and characterized an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. New results on RF characterization up to 20 GHz are presented. The detector fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing

Phase I trial of the combination of the Akt inhibitor nelfinavir and chemoradiation for locally advanced rectal cancer

PURPOSE: To investigate the toxicity of nelfinavir, administered during preoperative chemoradiotherapy (CRT) in patients with locally advanced cancer. MATERIAL AND METHODS: Twelve patients were treated with to 50.4Gy combined with capecitabine 825mg/m2 BID. Three dose levels nelfinavir were tested: 750mg BID (DL1), 1250mg BID (DL2) and an level of 1000mg BID (DL3). Surgery was performed between 8 and 10weeks completion of CRT. Primary endpoint was dose-limiting toxicity (DLT), any grade 3 or higher non-hematological or grade 4 or higher toxicity. RESULTS: Eleven patients could be analyzed: 5 were treated in DL2 and 3 in DL3. The first 3 patients in DL1 did not develop a DLT. In patient developed gr 3 diarrhea, 1 patient had gr 3 transaminase patient had a gr 3 cholangitis with unknown cause. An intermediate dose tested in DL3. In this group 2 patients developed gr 3 diarrhea and 1 3 transaminase elevation and gr 4 post-operative wound complication. patients achieved a pathological complete response (pCR). CONCLUSIONS: 750mg BID was defined as the recommended phase II dose in combination capecitabine and 50.4Gy pre-operative radiotherapy in rectal cancer. response evaluations are promising, but a further phase II study is more information about efficacy of this treatment regimen