Tomography by noise

We present an efficient and robust method for the reconstruction of photon number distributions by using solely thermal noise as a probe. The method uses a minimal number of pre-calibrated quantum devices, only one on/off single-photon detector is sufficient. Feasibility of the method is demonstrated by the experimental inference of single-photon, thermal and two-photon states. The method is stable to experimental imperfections and provides a direct, user-friendly quantum diagnostics tool

Direct amplitude modulation of short-cavity GaAs lasers up to X-band frequencies

Experimental and theoretical studies indicate that a high-frequency laser with bandwidths up to X-band frequencies (~> 10 GHz) should be one having a short cavity with a window structure, and preferably operating at low temperatures. These designs would accomplish the task of shortening the photon lifetime, increasing the intrinsic optical gain, and increasing the internal photon density without inflicting mirror damage. A modulation bandwidth of >8 GHz has been achieved using a 120-µm laser without any special window structure at room temperature

Superluminescent damping of relaxation resonance in the modulation response of GaAs lasers

It is demonstrated experimentally that the intrinsic modulation response of injection lasers can be modified by reducing mirror reflectivities, which leads to suppression of relaxation oscillation resonance and a reduction of nonlinear distortions up to multi-GHz frequencies. A totally flat response with a 3-dB bandwidth of 5 GHz was obtained using antireflection coated buried heterostructure lasers fabricated on a semi-insulating substrate. Harmonic distortions were below 40 dB within the entire 3-dB bandwidth. These results are in accord with theoretical predictions based on an analysis which include the effects of superluminescence in the laser cavity

Monolithic integration of a GaAlAs buried-heterostructure laser and a bipolar phototransistor

A GaAlAs buried-heterostructure laser has been monolithically integrated with a bipolar phototransistor. The heterojunction transistor was formed by the regrowth of the burying layers of the laser. Typical threshold current values for the lasers were 30 mA. Common-emitter current gains for the phototransistor of 100–400 and light responsivity of 75 A/W (for wavelengths of 0.82 µm) at collector current levels of 15 mA were obtained

X-ray ptychography on low-dimensional hard-condensed matter materials

Tailoring structural, chemical, and electronic (dis-)order in heterogeneous media is one of the transformative opportunities to enable new functionalities and sciences in energy and quantum materials. This endeavor requires elemental, chemical, and magnetic sensitivities at the nano/atomic scale in two- and three-dimensional space. Soft X-ray radiation and hard X-ray radiation provided by synchrotron facilities have emerged as standard characterization probes owing to their inherent element-specificity and high intensity. One of the most promising methods in view of sensitivity and spatial resolution is coherent diffraction imaging, namely, X-ray ptychography, which is envisioned to take on the dominance of electron imaging techniques offering with atomic resolution in the age of diffraction limited light sources. In this review, we discuss the current research examples of far-field diffraction-based X-ray ptychography on two-dimensional and three-dimensional semiconductors, ferroelectrics, and ferromagnets and their blooming future as a mainstream tool for materials sciences

The UW digital ozonesonde: Characteristics and flow rate calibration

During the austral springs of 1986 and 1987, a series of balloon soundings were conducted to characterize the temporal and vertical development of Antarctic ozone depletion using the electrochemical concentration cell method (ECC). An important part of this study was to perform correlative studies between ozone and aerosol particles. In order to facilitate these simultaneous measurements, a digital ozonesonde system was developed to interface with aerosol counters. The ozone measurements will be described herein. The ozonesonde modification was accomplished by converting the current output of the sonde to a frequency and adding this digital signal to the serial data stream of a Vaisala Corporation RS-80 radiosonde under microprocessor control. A number of advantages over the standard ozonesonde system currently in use are noted

Advanced materials development under NASA\u27s Hybrid Thermally Efficient Core (HyTEC) project

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Solid particle erosion of environmental barrier coatings and ceramic matrix composites

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