Optical coherence tomography (OCT) has steadily increased in scope with new applications continuing to arise. However, a major obstacle to the more widespread use of OCT is the limited scan area that can be achieved. In recent years, OCT systems using 3D eye tracking technologies and robotic arms for automatic detection and alignment of an OCT imaging system with a patient’s eye in ophthalmology have been demonstrated. This has enabled OCT without the need for precise manual alignment and stabilization of patients in ophthalmology. For non-clinical and low-cost applications, however, simple and compact automatically aligning OCT systems still need to be developed. In this work, a high-speed automatically aligning tabletop OCT beam scanning device with a simple and compact design incorporating a stereo camera and a high-speed translation stage is presented. The device automatically detects regions of interest on a sample in a 7.5×7.5cm area above the scanner, locates their three-dimensional position, and performs a synchronous alignment and scanning procedure to obtain high-quality OCT data from multiple regions at high speed. The acquisition of epidermal and dermal fingerprints for OCT-based fingerprint recognition is demonstrated. Four fingers on a user’s hand are detected, located in three-dimensional space and sequentially scanned in less than 2.3s, with the potential for scan times as low as 1.3s with faster lasers. It is envisioned that this compact tabletop scanner will enable a variety of applications in biometrics, dermatology and non-destructive testing where the high-speed acquisition of high-quality tomographic images with a compact device is desirable.
Owing to the fast-acquisition times and long-imaging ranges provided by swept-source optical coherence tomography (SSOCT), it has seen widespread commercial success in a wide range of real world applications. However, the high-cost and bulky size of swept-source lasers limits the potential application range of the technology. Here, a SS-OCT system utilizing a low-cost and compact wavelength-tunable laser designed for telecommunications is presented. The limited tuning range and discontinuous tuning of the telecommunications laser, is overcome through the use of compressed sensing, enabling the acquisition of OCT scans with enhanced resolutions and signal-to-noise ratios.
Due to the strong demand for photonic computing, on-chip optical communication, medical imaging, and biosensing at the nanoscale, interest in nanolasers has grown dramatically in recent years. Plasmonic lasers are promising as nanoscale laser sources and have been widely studied using semiconductor nanowires on metal surfaces grown by bottom-up techniques. However, these nanowire plasmonic lasers require transfer and positioning after fabrication, making their use in practical on-chip devices difficult.
In this study, we demonstrate a monolithically fabricated plasmonic-waveguide nanolaser. This is the first report showing a non-transfer plasmonic-waveguide nanolaser with a structure size (not only the mode size) in the sub-wavelength regime. A plasmonic waveguided mode capable of sustaining lasing is carefully designed so that top-down fabrication techniques can be used (no need of nanostructure transfer) to simultaneous fabricate the nanolasers together with waveguides for an optical circuit. Moreover, the design supports a lasing mode with a large effective area and confines the absorption of the pump light to the area in which the plasmonic-waveguide mode is most intense, reducing the lasing threshold. Lasing up to room temperature with a low threshold intensity of 0.20 mJ/cm^2 is demonstrated.
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