Embodiments of the present disclosure provide a prosthetic heart valve and a heart valve delivery apparatus for delivery of the prosthetic heart valve to a native valve site via the human vasculature. The delivery apparatus is particularly suited for advancing a prosthetic valve through the aorta (i.e., in a retrograde approach) for replacing a diseased native aortic valve. In one embodiment, a self-expanding valve comprises an expandable stent that is shaped to maintain the valve in the aortic annulus against axial without anchors or retaining devices that engage the surrounding tissue. A delivery apparatus for delivering s self-expanding prosthetic valve can be configured to allow controlled and precise deployment of the valve from a valve sheath so as to minimize or prevent jumping of the valve from the valve sheath.

Prosthetic heart valve and delivery apparatus

Polarization-state selection, polarization-state dynamics, and polarization switching of a quantum-well vertical-cavity surface-emitting laser (VCSEL) for the lowest order transverse spatial mode of the laser is explored using a recently developed model that incorporates material birefringence, the saturable dispersion characteristic of semiconductor physics, and the sensitivity of the transitions in the material to the vector character of the electric field amplitude. Three features contribute to the observed linearly polarized states of emission: linear birefringence, linear gain or loss anisotropies, and an intermediate relaxation rate for imbalances in the populations of the magnetic sublevels. In the absence of either birefringence or saturable dispersion, the gain or loss anisotropies dictate stability for the linearly polarized mode with higher net gain; hence, switching is only possible if the relative strength of the net gain for the two modes is reversed. When birefringence and saturable dispersion are both present, there are possibilities of bistability, monostability, and dynamical instability, including switching by destabilization of the mode with the higher gain to loss ratio in favor of the weaker mode. We compare our analytical and numerical results with recent experimental results on bistability and switchings caused by changes in the injection current and changes in the intensity of an injected optical signal.

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Polarization properties of vertical-cavity surface-emitting lasers

Certain embodiments of the present disclosure provide a prosthetic valve (e.g., prosthetic heart valve) and a valve delivery apparatus for delivery of the prosthetic valve to a native valve site via the human vasculature. The delivery apparatus is particularly suited for advancing a prosthetic heart valve through the aorta (i.e., in a retrograde approach) for replacing a diseased native aortic valve. The delivery apparatus in particular embodiments is configured to deploy a prosthetic valve from a delivery sheath in a precise and controlled manner at the target location within the body.

Prosthetic heart valve delivery apparatus

We demonstrate integration of GaAs-AlGaAs multiple quantum well modulators to silicon CMOS circuitry via flip-chip solder-bonding followed by substrate removal. We obtain 95% device yield for 32/spl times/32 arrays of devices with 15 micron solder pads. We show operation of a simple circuit composed of a modulator and a CMOS transistor. >

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GaAs MQW modulators integrated with silicon CMOS

Ion implantation for isolation of III-V semiconductors

We report the observation of bistable polarization switching in a vertical‐cavity surface‐emitting laser under optical injection. The wavelength dependence of the switching is measured. It is found that this polarization switching is achieved through injection locking where both the wavelength and the polarization of the vertical‐cavity laser are locked to the injected optical signal.

Optical injection induced polarization bistability in vertical‐cavity surface‐emitting lasers

Transverse mode characteristics and control for vertical-cavity top-surface-emitting lasers (VCSELs) are discussed. A spatial filtering concept for the control of VCSEL transverse modes that allows over 1.5-mW single TEM/sub 00/ transverse mode emission to be routinely achieved from continuous-wave electrically excited VCSELs is introduced. Without spatial filtering, L-I and V-I kinks are observed. >

Transverse mode control of vertical-cavity top-surface-emitting lasers

We demonstrate record high pulsed output power exceeding 530 mW from an electrically pumped phase‐coupled 8×8 vertical cavity surface emitting laser array (SELA) at room temperature. Three array types are compared: an 8×8 pixellated SELA(PSELA), an 8×8 grid contact SELA(CSELA), and a 78 μm×78 μm single broad area SEL(BSEL) emitter. The CSELA operating in a phase‐coupled supermode exhibits the lowest threshold current (100 mA) and voltage (1.6 V), highest damage threshold and a smooth L‐I characteristic with differential quantum efficiency ηd≳27%, the BSEL has the largest output power≳580 mW and a large ηd≳48%, the PSELA exhibited a large voltage with the largest ηd≳80%.

High‐power coherently coupled 8×8 vertical cavity surface emitting laser array

We report batch-processed, totally planar, vertical-cavity top surface emitting GaAs/AlGaAs laser devices and arrays. Different size devices are studied experimentally. We measure continuous-wave threshold currents down to 1.7 mA and output powers > 3.7 mW at room temperature. We also discuss interesting characteristics such as differential quantum efficiencies exceeding unity and multi-transverse mode behavior. An array having 64 X 1 individually-accessed elements is characterized and shown to have uniform room-temperature continuous-wave operating characteristics in threshold current approximately equals 2.1 +/- 0.1 mA, wavelength approximately equals 849.4 +/- 0.8 nm, and output power approximately equals 0.5 +/- 0.1 mW.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Progress in planarized vertical cavity surface emitting laser devices and arrays

Symmetric self‐electro‐optic effect devices (S‐SEEDs) using extremely shallow GaAs/Al0.04Ga0.96As multiple quantum wells are demonstrated. By exploiting mainly exciton ionization, rather than the usual quantum‐confined Stark shift, room‐temperature optical bistability is obtained with no applied bias. The extremely shallow symmetric‐SEED (symmetric E‐SEED) exhibits contrast ratios (CRs)≂3.5, with biasses<5 V, demonstrating system applicability and compatability with electronics. Large system tolerances Δλ≂6 nm and maximum bistability loop width ≂70% are also obtained. Moreover, due to fast carrier escape times, the symmetric E‐SEED exhibits useful CRs≳2 even at continuous‐wave intensities ≳70 μW/μm2.

Marlin W. Focht

Papers

Optical injection induced polarization bistability in vertical‐cavity surface‐emitting lasers

Transverse mode control of vertical-cavity top-surface-emitting lasers

High‐power coherently coupled 8×8 vertical cavity surface emitting laser array

Progress in planarized vertical cavity surface emitting laser devices and arrays

Low‐voltage, high‐saturation, optically bistable self‐electro‐optic effect devices using extremely shallow quantum wells