Correction of Multispectral Singlet Oxygen Luminescent Dosimetry (MSOLD) for Tissue Optical Properties in Photofrin-Mediated Photodynamic Therapy.

The direct detection of singlet-state oxygen (O) constitutes the holy grail dosimetric method for type-II photodynamic therapy (PDT), a goal that can be quantified using multispectral singlet oxygen near-infrared luminescence dosimetry (MSOLD). The optical properties of tissues, specifically their scattering and absorption coefficients, play a crucial role in determining how the treatment and luminescence light are attenuated. Variations in these properties can significantly impact the spatial distribution of the treatment light and hence the generation of singlet oxygen and the detection of singlet oxygen luminescence signals.

Ecological-niche modeling reveals current opportunities for Agave dryland farming in Sonora, Mexico and Arizona, USA.

For centuries, humans occupying arid regions of North America have maintained an intricate relationship with Agave (Agavoideae, Asparagaceae). Today Agave cultivation, primarily for beverage production, provides an economic engine for rural communities throughout Mexico. Among known dryland-farming methods, the use of rock piles and cattle-grazed areas stand out as promising approaches for Agave cultivation.

Multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated Photodynamic Therapy.

Direct detection of singlet-state oxygen ([O]) constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). However, the short lifetime and extremely weak nature of the singlet oxygen signal produced has given rise to a need to improve MSOLD signal-to-noise ratio. This study examines methods for optimizing MSOLD signal acquisition, specifically employing an orthogonal arrangement between detection and PDT treatment light, consisting of two fiber optics - connected to a 632-nm laser and an InGaAs detector respectively.

Analysis of Excitability in Resonant Tunneling Diode-Photodetectors.

We investigate the dynamic behaviour of resonant tunneling diode-photodetectors (RTD-PDs) in which the excitability can be activated by either electrical noise or optical signals. In both cases, we find the characteristics of the stochastic spiking behavior are not only dependent on the biasing positions but also controlled by the intensity of the input perturbations. Additionally, we explore the ability of RTD-PDs to perform optical signal transmission and neuromorphic spike generation simultaneously.

Two-photon quantum interference and entanglement at 2.1 μm.

Quantum-enhanced optical systems operating within the 2- to 2.5-μm spectral region have the potential to revolutionize emerging applications in communications, sensing, and metrology. However, to date, sources of entangled photons have been realized mainly in the near-infrared 700- to 1550-nm spectral window.

Photon counting LIDAR at 2.3µm wavelength with superconducting nanowires.

In this work, we show a proof-of-principle benchtop single-photon light detection and ranging (LIDAR) depth imager at 2.3µm, utilizing superconducting nanowire single-photon detectors (SNSPDs). We fabricate and fiber-couple SNSPDs to exhibit enhanced photon counting performance in the mid-infrared.

Design and Characterisation of Titanium Nitride Subarrays of Kinetic Inductance Detectors for Passive Terahertz Imaging.

We report on the investigation of titanium nitride (TiN) thin films deposited via atomic layer deposition (ALD) for microwave kinetic inductance detectors (MKID). Using our in-house ALD process, we have grown a sequence of TiN thin films (thickness 15, 30, 60 nm). The films have been characterised in terms of superconducting transition temperature , sheet resistance and microstructure.

High-extinction ratio integrated photonic filters for silicon quantum photonics.

We present the generation of quantum-correlated photon pairs and subsequent pump rejection across two silicon-on-insulator photonic integrated circuits. Incoherently cascaded lattice filters are used to provide over 100 dB pass-band to stop-band contrast with no additional external filtering. Photon pairs generated in a microring resonator are successfully separated from the input pump, confirmed by temporal correlations measurements.

A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy.

Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT-light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([³₂])-to calculate the amount of reacted singlet oxygen ([¹₂]), the main cytotoxic component in type II PDT.

Superconducting nanowire single-photon detectors with non-periodic dielectric multilayers.

We present superconducting nanowire single-photon detectors (SSPDs) on non-periodic dielectric multilayers, which enable us to design a variety of wavelength dependences of optical absorptance by optimizing the dielectric multilayer. By adopting a robust simulation to optimize the dielectric multilayer, we designed three types of SSPDs with target wavelengths of 500 nm, 800 nm, and telecom range respectively. We fabricated SSPDs based on the optimized designs for 500 and 800 nm, and evaluated the system detection efficiency at various wavelengths.

A compact fiber-optic probe-based singlet oxygen luminescence detection system.

This paper presents a novel compact fiberoptic based singlet oxygen near-infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single-photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers.

Nano-optical single-photon response mapping of waveguide integrated molybdenum silicide (MoSi) superconducting nanowires.

We present low temperature nano-optical characterization of a silicon-on-insulator (SOI) waveguide integrated SNSPD. The SNSPD is fabricated from an amorphous MoSi thin film chosen to give excellent substrate conformity. At 350 mK, the SNSPD exhibits a uniform photoresponse under perpendicular illumination, corresponding to a maximum system detection efficiency of approximately 5% at 1550 nm wavelength.

A feasibility study of singlet oxygen explicit dosmietry (SOED) of PDT by intercomparison with a singlet oxygen luminescence dosimetry (SOLD) system.

An explicit dosimetry model has been developed to calculate the apparent reacted concentration ([]) in an model. In the model, a macroscopic quantity, , is introduced to account for oxygen perfusion to the medium during PDT. In this study, the SOED model is extended for PDT treatment in phantom conditions where vasculature is not present; the oxygen perfusion is achieved through the air-phantom interface instead.

Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits.

Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable.

Nanoantenna enhancement for telecom-wavelength superconducting single photon detectors.

Superconducting nanowire single photon detectors are rapidly emerging as a key infrared photon-counting technology. Two front-side-coupled silver dipole nanoantennas, simulated to have resonances at 1480 and 1525 nm, were fabricated in a two-step process. An enhancement of 50 to 130% in the system detection efficiency was observed when illuminating the antennas.

Optimised quantum hacking of superconducting nanowire single-photon detectors.

We explore bright-light control of superconducting nanowire single-photon detectors (SNSPDs) in the shunted configuration (a practical measure to avoid latching). In an experiment, we simulate an illumination pattern the SNSPD would receive in a typical quantum key distribution system under hacking attack. We show that it effectively blinds and controls the SNSPD.

Complete tomography of a high-fidelity solid-state entangled spin-photon qubit pair.

Entanglement between stationary quantum memories and photonic qubits is crucial for future quantum communication networks. Although high-fidelity spin-photon entanglement was demonstrated in well-isolated atomic and ionic systems, in the solid-state, where massively parallel, scalable networks are most realistically conceivable, entanglement fidelities are typically limited due to intrinsic environmental interactions. Distilling high-fidelity entangled pairs from lower-fidelity precursors can act as a remedy, but the required overhead scales unfavourably with the initial entanglement fidelity.

Kilometer-range, high resolution depth imaging via 1560 nm wavelength single-photon detection.

This paper highlights a significant advance in time-of-flight depth imaging: by using a scanning transceiver which incorporated a free-running, low noise superconducting nanowire single-photon detector, we were able to obtain centimeter resolution depth images of low-signature objects in daylight at stand-off distances of the order of one kilometer at the relatively eye-safe wavelength of 1560 nm. The detector used had an efficiency of 18% at 1 kHz dark count rate, and the overall system jitter was ~100 ps. The depth images were acquired by illuminating the scene with an optical output power level of less than 250 µW average, and using per-pixel dwell times in the millisecond regime.

Singlet oxygen luminescence detection with a fiber-coupled superconducting nanowire single-photon detector.

Direct monitoring of singlet oxygen (¹O₂) luminescence is a particularly challenging infrared photodetection problem. ¹O₂, an excited state of the oxygen molecule, is a crucial intermediate in many biological processes. We employ a low noise superconducting nanowire single-photon detector to record ¹O₂ luminescence at 1270 nm wavelength from a model photosensitizer (Rose Bengal) in solution.

Quantum detector tomography of a time-multiplexed superconducting nanowire single-photon detector at telecom wavelengths.

Superconducting nanowire single-photon detectors (SNSPDs) are widely used in telecom wavelength optical quantum information science applications. Quantum detector tomography allows the positive-operator-valued measure (POVM) of a single-photon detector to be determined. We use an all-fiber telecom wavelength detector tomography test bed to measure detector characteristics with respect to photon flux and polarization, and hence determine the POVM.

Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel.

Long-distance quantum communication networks require appropriate interfaces between matter qubit-based nodes and low-loss photonic quantum channels. We implement a downconversion quantum interface, where the single photons emitted from a semiconductor quantum dot at 910 nm are downconverted to 1560 nm using a fiber-coupled periodically poled lithium niobate waveguide and a 2.2-μm pulsed pump laser.

Subtalar joint septic arthritis in a patient with hypogammaglobulinemia.

The clinical presentation of a monoarticular, red, hot, and swollen joint has many possible diagnoses, including septic arthritis, which is 1 of the most devastating. The morbidity associated with this pathologic process involves permanent joint damage and the potential for progression to systemic illness and, even, mortality. The common risk factors for joint sepsis include a history of rheumatoid arthritis, previous joint surgery, joint prosthesis, intravenous drug abuse, alcoholism, diabetes, previous intra-articular steroid use, and cutaneous ulceration.

Analysis of a distributed fiber-optic temperature sensor using single-photon detectors.

We demonstrate a high-accuracy distributed fiber-optic temperature sensor using superconducting nanowire single-photon detectors and single-photon counting techniques. Our demonstration uses inexpensive single-mode fiber at standard telecommunications wavelengths as the sensing fiber, which enables extremely low-loss experiments and compatibility with existing fiber networks. We show that the uncertainty of the temperature measurement decreases with longer integration periods, but is ultimately limited by the calibration uncertainty.