Optical feedback in lasers is being used for unconventional imaging of fluid dynamics, pressure fields, material properties, and free-carrier distribution, especially in spectral regions where two-dimensional detectors are not yet available. As this technique requires scanning the laser spot across the target, the resulting image contrast is often hampered by the speckle effect. Compressed sensing is becoming a workhorse technique for signal analysis, allowing the reconstruction of complex images from a relatively small number of integrated (single-pixel) measurements, and is being efficiently adapted to a number of single-pixel detector cameras. We applied compressed sensing algorithms to the inherently single-pixel optical feedback in a semiconductor diode laser, demonstrating for the first time, to the best of our knowledge, scanless and detectorless speckle-free imaging of a simple binary object.
We experimentally demonstrate a cost-effective dual-polarization quadrature phase shift keying (DP-QPSK) coherent passive optical network (PON) system that operates at 100 Gbits/s/λ. This system utilizes distributed feedback lasers (DFBs) and a carrier recovery algorithm facilitated by a bifunctional frequency-domain pilot tone (FPT). To reduce costs in coherent PON implementations, low-cost DFBs are employed as the sole light sources, replacing the more expensive external cavity lasers (ECLs) at both the optical line terminal (OLT) and the optical network units (ONUs).
An ultra-narrow-linewidth laser is a core device in fields such as optical atomic clocks, quantum communications, and microwave photonic oscillators. This paper reports an ultra-narrow-linewidth self-injection locked semiconductor laser, which is realized through optical feedback from a high-Q (258 million) Fabry-Perot (FP) cavity constructed with three mirrors, generating an output power of 12 mW. Employing a delay self-heterodyne method based on a signal source analyzer, the phase noise of the laser is -129 dBc/Hz at 100 kHz offset frequency, with an intrinsic linewidth of 3 mHz.
A compact and robust optical excitation photoacoustic sensor with a self-integrated laser module excitation and an optimized differential resonator was developed to achieve high sensitivity and full linear range detection of carbon dioxide (CO) based on dual modes of wavelength modulated photoacoustic spectroscopy (WMPAS) and resonant frequency tracking (RFT). The integrated laser module equipped with three lasers (a quantum cascade laser (QCL), a distributed feedback laser (DFB) and a He-Ne laser) working in a time-division multiplexing mode was used as an integrated set of spectroscopic sources for detection of the designated concentration levels of CO. With the absorption photoacoustic mode, the WMPAS detection with the QCL and DFB sources was capable of CO detection at concentrations below 20 %, yielding a noise equivalent concentration (NEC) as low as 240 ppt and a normalized noise equivalent absorption coefficient (NNEA) of 4.
Background: The Senhance digital laparoscopic system (Senhance) is a surgical robot approved for use in Japan after the da Vinci system. Our institution was the first to introduce this system, which has been used primarily for gastrointestinal surgery. Featuring tactile feedback, eye-movement-controlled camera operation, stereoscopic vision, and magnification, the short-term postoperative outcomes of the Senhance in abdominal surgery have been documented.
The Senhance robotic system (Asensus Surgical, Durham, NC, USA) is an innovative platform for minimally invasive surgery. It enables surgeons to perform precise and cost-effective procedures using reusable instruments and has advanced features such as haptic feedback and eye-tracking camera control. Herein, we present the first application of the "double bipolar method" (DBM) in a Senhance-assisted laparoscopic partial cystectomy utilizing 3 mm Maryland bipolar instruments.
