On-chip spectroscopy with thermally-tuned high-Q photonic crystal cavities

Spectroscopic methods are a sensitive way to determine the chemical composition of potentially hazardous materials. Here, we demonstrate that thermally-tuned high-Q photonic crystal cavities can be used as a compact high-resolution on-chip spectrometer. We have used such a chip-scale spectrometer to measure the absorption spectra of both acetylene and hydrogen cyanide in the 1550 nm spectral band, and show that we can discriminate between the two chemical species even though the two materials have spectral features in the same spectral region. Our results pave the way for the development of chip-size chemical sensors that can detect toxic substances

Quantum Hilbert hotel

In 1924 David Hilbert conceived a paradoxical tale involving a hotel with an infinite number of rooms to illustrate some aspects of the mathematical notion of “infinity.” In continuous-variable quantum mechanics we routinely make use of infinite state spaces: here we show that such a theoretical apparatus can accommodate an analog of Hilbert’s hotel paradox. We devise a protocol that, mimicking what happens to the guests of the hotel, maps the amplitudes of an infinite eigenbasis to twice their original quantum number in a coherent and deterministic manner, producing infinitely many unoccupied levels in the process. We demonstrate the feasibility of the protocol by experimentally realizing it on the orbital angular momentum of a paraxial field. This new non-Gaussian operation may be exploited, for example, for enhancing the sensitivity of NOON states, for increasing the capacity of a channel, or for multiplexing multiple channels into a single one

Inflammatory pseudotumor associated with Mycobacterium tuberculosis infection

SummaryBackgroundInflammatory pseudotumor is a relatively rare entity; originally identified in the lung, it has been described in multiple extrapulmonary anatomic locations.Case reportWe report on the unusual case of an inflammatory pseudotumor associated with Mycobacterium tuberculosis infection, which was initially mistaken for a renal malignancy both in clinical and radiological settings. We additionally present three brief reviews concerning: (1) infectious agents postulated to induce morphological changes of an inflammatory pseudotumor; (2) mycobacterial pseudotumors; and (3) distinction from inflammatory myofibroblastic tumors of the renal pelvis.ConclusionsThe present case highlights the diagnostic importance of PCR-based detection of mycobacterial DNA in granulomatous tissue responses. It is of crucial importance that clinicians are aware of this unusual manifestation of mycobacterial infection to ensure that pertinent laboratory evaluation is employed and appropriate treatment is administered in order to avoid potential clinical implications

Silicon photonics-based high-energy passively Q-switched laser

Chip-scale, high-energy optical pulse generation is becoming increasingly important as integrated optics expands into space and medical applications where miniaturization is needed. Q-switching of the laser cavity was historically the first technique to generate high-energy pulses, and typically such systems are in the realm of large bench-top solid-state lasers and fibre lasers, especially in the long wavelength range &gt;1.8 µm, thanks to their large energy storage capacity. However, in integrated photonics, the very property of tight mode confinement that enables a small form factor becomes an impediment to high-energy applications owing to small optical mode cross-sections. Here we demonstrate a high-energy silicon photonics-based passively Q-switched laser with a compact footprint using a rare-earth gain-based large-mode-area waveguide. We demonstrate high on-chip output pulse energies of &gt;150 nJ and 250 ns pulse duration in a single transverse fundamental mode in the retina-safe spectral region (1.9 µm), with a slope efficiency of ~40% in a footprint of ~9 mm2. The high-energy pulse generation demonstrated in this work is comparable to or in many cases exceeds that of Q-switched fibre lasers. This bodes well for field applications in medicine and space.</p

Reconstructive spectrometers taper down in price

Publisher Copyright: © 2023, The Author(s).The development of a low-cost compact reconstructive spectrometer paves the way towards portable pm-resolution spectroscopy.Peer reviewe

Optical time delays in structured media

Thesis (Ph. D.)--University of Rochester. Institute of Optics, 2015.`How long does it take for light to go from point A to point B'? Ever since the observations by Rømer in the 17th century and the experiments of Fizeau and Foucault in the 19th century which showed that light has a finite velocity, researchers have been looking for ways to control the propagation of light. This topic became even more intriguing when, years after Einstein postulated that the 'speed of light c is, in fact, a universal speed limit, experiments were reported that seemingly violated this rule. Today we know that there are many different velocities that relate to the propagation of light, and that not all of them are bounded by this limit. The present work deals with the propagation of light through structured media, material systems, in other words, whose optical properties vary in space, usually on a length scale of the order of the wavelength of light. We will see that the behavior of light in such media can be drastically different than that in free space. We will examine the various definitions of time delay and how they relate to the electromagnetic energy stored in the medium. Then we will consider two different material systems: Firstly, in silicon photonics, we will use photonic crystal cavities to trap light on a chip, and waveguides to control its propagation. We will also examine how this control can enable us to construct ultra-compact high-resolution spectrometers. Secondly, using a Hong-Ou-Mandel interferometer we will perform time-delay experiments through various types of liquid crystals. Since these experiments are performed at the single photon level, they can help us address fundamental questions about causality and quantum mechanics, and resolve a decades-old paradox

Primary Malignant Melanoma of Renal Pelvis with Extensive Clear Cell Change.

Our presentation illustrates a rare case of primary renal pelvis malignant melanoma in a 35-year-old man. The diagnosis of malignant melanoma was based on immunophenotype and the detection of intracellular melanin pigment. The renal origin was proven by the presence of scattered melanocytes within the urothelium of the pelvis. The tumor exhibited extensive clear cell change that closely mimics clear cell renal cell carcinoma. The patient&apos;s clinical history did not disclose any signs of previous melanocytic skin or mucosa lesions. Differential diagnosis includes tumors capable of synthesizing melanin or expressing melanocytic markers