Recent developments in monolithic integration of InGaAsP/InP optoelectronic devices

Monolithically integrated optoelectronic circuits combine optical devices such as light sources (injection lasers and light emitting diodes) and optical detectors with solid-state semiconductor devices such as field effect transistors, bipolar transistors, and others on a single semiconductor crystal. Here we review some of the integrated circuits that have been realized and discuss the laser structures suited for integration with emphasis on the InGaAsP/InP material system. Some results of high frequency modulation and performance of integrated devices are discussed

Surfin' pp-waves with Good Vibrations: Causality in the presence of stacked shockwaves

Relativistic causality constrains the $S$-matrix both through its analyticity, and by imposing lower bounds on the scattering time delay. These bounds are easiest to determine for spacetimes which admit either a timelike or null Killing vector. We revisit a class of pp-wave spacetimes and carefully determine the scattering time delay for arbitrary incoming states in the eikonal, semi-classical, and Born approximations. We apply this to the EFT of gravity in arbitrary dimensions. It is well-known that higher-dimension operators such as the Gauss-Bonnet term, when treated perturbatively at low energies, can appear to make both positive and negative contributions to the time delays of the background geometry. We show that even when multiple shockwaves are stacked, the corrections to the scattering time delay relative to the background are generically unresolvable within the regime of validity of the effective field theory so long as the Wilson coefficients are of order unity. This is in agreement with previously derived positivity/bootstrap bounds and the requirement that infrared causality be maintained in consistent low-energy effective theories, irrespective of the UV completion.Comment: 68 pages, 3 figure

Realization of a complete Stern-Gerlach interferometer: Toward a test of quantum gravity

The Stern-Gerlach effect, found a century ago, has become a paradigm of quantum mechanics. Unexpectedly, until recently, there has been little evidence that the original scheme with freely propagating atoms exposed to gradients from macroscopic magnets is a fully coherent quantum process. Several theoretical studies have explained why a Stern-Gerlach interferometer is a formidable challenge. Here, we provide a detailed account of the realization of a full-loop Stern-Gerlach interferometer for single atoms and use the acquired understanding to show how this setup may be used to realize an interferometer for macroscopic objects doped with a single spin. Such a realization would open the door to a new era of fundamental probes, including the realization of previously inaccessible tests at the interface of quantum mechanics and gravity

High-power, single-mode operation of an InGaAsP/InP laser with a grooved transverse junction using gain stabilization

The high-power performance of a groove InGaAsP/InP transverse junction laser fabricated on a semi-insulating InP substrate has been investigated. Peak power of over 250 mW/facet for pulsed operation and 11 mW/facet cw are achieved with stable fundamental mode operation and narrow beam width. It is suggested that the single-mode operation is caused by a gain stabilizing mechanism related to the transverse junction injection profiles

T^3-Stern-Gerlach Matter-Wave Interferometer

We present a unique matter-wave interferometer whose phase scales with the cube of the time the atom spends in the interferometer. Our scheme is based on a full-loop Stern-Gerlach interferometer incorporating four magnetic field gradient pulses to create a state-dependent force. In contrast to typical atom interferometers which make use of laser light for the splitting and recombination of the wave packets, this realization uses no light and can therefore serve as a high-precision surface probe at very close distances.Comment: Phys. Rev. Lett., in print, https://journals.aps.org/prl

A new infrared detector using electron emission from multiple quantum wells

A new type of infrared photodetector using free electron absorption in a heavily doped GaAs/GaAlAs quantum well structure has been demonstrated. Preliminary results indicate a strong response in the near infrared with a responsivity conservatively estimated at 200 A/W. The structure can potentially be tailored during fabrication for use in several infrared bands of interest, including the 3 to 5 micron band and the 8 to 10 micron band

Mode stabilization mechanism of buried-waveguide lasers with lateral diffused junctions

The mode stabilization behavior of the buried active waveguide with lateral diffused junction is theoretically investigated. The study shows that for an active waveguide of width around 5 μm with a lateral diffused junction in the middle, the single fundamental transverse mode is preferred as the injection level is raised. The theoretical results are found to be in good agreement with experimental results observed in the groove transverse junction InGaAsP/InP laser

T 3 Stern-Gerlach matter-wave interferometer

The article of record as published may be found at https://doi.org/10.1103/PhysRevLett.123.083601We present a unique matter-wave interferometer whose phase scales with the cube of the time the atom spends in the interferometer. Our scheme is based on a full-loop Stern-Gerlach interferometer incorporating four magnetic field gradient pulses to create a state-dependent force. In contrast to typical atom interferometers which make use of laser light for the splitting and recombination of the wave packets, this realization uses no light and can therefore serve as a high-precision surface probe at very close distances.This work is funded in part by the Israel Science Foundation (grant No. 856/18) and the German- Israeli DIP projects (Hybrid devices: FO 703/2-1, AR 924/1-1, DU 1086/2-1) supported by the DFG. We also acknowledge support from the Israeli Council for Higher Education (Israel). M.A.E. is thankful to the Center for Integrated Quantum Science and Technology (IQST ) for its generous financial support. W.P.S. is grateful to Texas A&M University for a Faculty Fellowship at the Hagler Institute for Advanced Study at Texas A&M University, and to Texas A&M AgriLife Research for the support of this work. The research of the IQST is financially supported by the Ministry of Science, Research and Arts, Baden-Wurttemberg. F.A.N. is grateful for a generous Laboratory University Collaboration Initiative (LUCI) grant from the Office of the Secretary of Defense.This work is funded in part by the Israel Science Foundation (grant No. 856/18) and the German- Israeli DIP projects (Hybrid devices: FO 703/2-1, AR 924/1-1, DU 1086/2-1) supported by the DFG. We also acknowledge support from the Israeli Council for Higher Education (Israel). M.A.E. is thankful to the Center for Integrated Quantum Science and Technology (IQST ) for its generous financial support. W.P.S. is grateful to Texas A&M University for a Faculty Fellowship at the Hagler Institute for Advanced Study at Texas A&M University, and to Texas A&M AgriLife Research for the support of this work. The research of the IQST is financially supported by the Ministry of Science, Research and Arts, Baden-Wurttemberg. F.A.N. is grateful for a generous Laboratory University Collaboration Initiative (LUCI) grant from the Office of the Secretary of Defense