Electromechanical wavelength tuning of double-membrane photonic crystal cavities

We present a method for tuning the resonant wavelength of photonic crystal cavities (PCCs) around 1.55 um. Large tuning of the PCC mode is enabled by electromechanically controlling the separation between two parallel InGaAsP membranes. A fabrication method to avoid sticking between the membranes is discussed. Reversible red/blue shifting of the symmetric/anti-symmetric modes has been observed, which provides clear evidence of the electromechanical tuning, and a maximum shift of 10 nm with < 6 V applied bias has been obtained.Comment: 9 pages, 3 figure

Demonstration of an ultra-short polarization converter in InGaAsP/InP membrane

An ultra-short (&lt;10 µm length) polarization converter is demonstrated in an indium phosphide based membrane. Measurements show very high polarization conversion efficiency (97 %) with low excess losses (~ 1 dB)

Teachers’ remaining career opportunities:The role of value fit and school climate

In light of an aging teacher population, this study investigates the influence of school climate and personschool (P-S) value fit on teachers' perspectives regarding their career futures. The results, based on a sample of 147 teachers, indicate that P-S value fit is positively associated with remaining career opportunities, over and above the negative effect of age. In addition, both climate for performance/academic press and climate for socialization affect teachers' future career perspectives through a P-S value fit mechanism. These findings imply that schools can enhance teachers’ perceived remaining career opportunities by creating strong school climates and improving perceived value fit. Keywords: Occupational future time perspective; Career opportunities; Person-school value fit; School climate; Teacher

Lateral arrangements of size and number controlled 1.55-μm InAs quantum dots on InP nanopyramids

Lateral arrangements of size and number controlled InAs quantum dots (QDs) on truncated InP (100) nanopyramids grown by selective area metalorganic vapor-phase epitaxy (MOVPE) are reported. The QDs nucleate on high-indexfacets on pyramids top allowing precise position and distribution control. The size and shape of QDs are related to As/P exchange determined by the growth temperature, as demonstrated for circular-based pyramids. The QD number is controlled by both the size of the highindex facets (governed by pyramids top area) and As/P exchange (governed by growth temperature). Sharp emission peaks from individual QDs are observed around 1.55 pm

Size dependent exciton g-factor in self-assembled InAs/InP quantum dots

We have studied the size dependence of the exciton g-factor in self-assembled InAs/InP quantum dots. Photoluminescence measurements on a large ensemble of these dots indicate a multimodal height distribution. Cross-sectional Scanning Tunneling Microscopy measurements have been performed and support the interpretation of the macro photoluminescence spectra. More than 160 individual quantum dots have systematically been investigated by analyzing single dot magneto-luminescence between 1200nm and 1600 nm. We demonstrate a strong dependence of the exciton g-factor on the height and diameter of the quantum dots, which eventually gives rise to a sign change of the g-factor. The observed correlation between exciton g-factor and the size of the dots is in good agreement with calculations. Moreover, we find a size dependent anisotropy splitting of the exciton emission in zero magnetic field.Comment: 15 pages, 7 figure

A 14b 200MS/s DAC with SFDR&gt;78dBc, IM3

A 14-bit 200MS/s current-steering DAC with a novel digital calibration technique called dynamic-mismatch mapping (DMM) is presented. Compared to traditional static-mismatch mapping and dynamic element matching, DMM reduces the nonlinearities caused by both amplitude and timing errors, without noise penalty. This 0.14µm CMOS DAC achieves a state-of-the-art performance of SFDR&gt;78dBc, IM

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

Nano-optomechanical fiber-tip sensing

Nano-optomechanical sensors exploit light confinement at the nanoscale to enable very precise measurements of displacement, force, acceleration, and mass. Their application is hampered by the complex optical set-ups or packaging schemes required to couple light to and from the nano-optomechanical resonator. In this work, we present a fiber-coupled nano-optomechanical sensor that requires no coupling optics. This is achieved by directly placing a nano-optomechanical structure, a double membrane photonic crystal (DM-PhC), on the facet of a fiber, using a simple and scalable wafer-to-fiber transfer method. The device is probed in reflection and has a resonance at telecom wavelengths with a relatively broad spectral width of 3–10 nm, which is advantageous for a simple read-out and achieves a displacement imprecision of $$10\,{{\rm{fm}}}/{\sqrt{{\rm{Hz}}}}$$. Using resonant driving and a ringdown measurement, we can induce and monitor mechanical oscillations with an nm-scale amplitude via the fiber, which allows for tracking the mechanical resonant frequency and the mechanical linewidth with imprecisions of 79 and 12 Hz, respectively, at integration times of 4.5 s. We further demonstrate the application of this fiber-tip sensor to the measurement of pressure, using the effect of collisional damping on the mechanical linewidth, leading to the imprecision of $$9\times {10}^{-4}\,{\rm{mbar}}$$with an integration time of 290 s. This combination of optomechanics and fiber-tip sensing may open the way to a new generation of fiber sensors with unprecedented functionality, ultrasmall footprint, and low-cost readout

Interventions for improving recovery from work

ObjectivesThis is a protocol for a Cochrane Review (intervention). The objectives are as follows:To compare the effectiveness of different individual interventions in recovery from work.info:eu-repo/semantics/publishedVersio

Low-loss passive waveguides in a generic InP foundry process via local diffusion of zinc

Generic InP foundry processes allow monolithic integration of active and passive elements into a common p-n doped layerstack. The passive loss can be greatly reduced by restricting the p-dopant to active regions. We report on a localized Zn-diffusion process based on MOVPE, which allows to reduce waveguide loss from 2 dB/cm to below 0.4 dB/cm. We confirm this value by fabrication of a 73 mm long spiral ring resonator, with a record quality factor of 1.2 million and an extinction ratio of 9.7 dB.</p