The effective pumping factor for various Laser Diodes (LDs) is defined to explain the absorption characteristic of wavelength-stable LDs (WS-LDs). This factor is used to determine wavelength locking points and residual pump power. We evaluated the wavelength locking ability and residual pump power in quantity using two groups of comparable LDs and a narrow linewidth fiber laser. Prior to running LDs in a fully wavelength-locked state, the maximum residual pump power is observed at low pump power levels. This information can be useful in engineering applications for establishing appropriate cooling standards for CPS heat load. Additionally, it is valuable for WS-LD manufacturers to provide a universal evaluation factor for assessing different LDs and guiding wavelength locking quantity enhancement.
Traditional optical imaging techniques are limited in terms of information acquisition and processing methods, as they can only image targets within the line of sight. Non-Line-of-Sight Imaging (NLOS) aims to enable imaging beyond the line of sight. One important method in NLOS imaging is based on the measurement of photon time-of-flight. It involves analyzing the paths of light propagation before reaching the detector to reconstruct the surface of hidden objects. In non-line-of-sight scenarios, light from non-line-of-sight objects can be imaged after being reflected by visible objects in the scene. However, the multiple reflected light signals in traditional imaging are typically considered as noise due to their low intensity. In contrast, non-line-of-sight imaging captures the weak and scattered light signals that have undergone multiple reflections, and uses the time of photon arrival to infer the shape of objects hidden from the line of sight. This paper explores the relationship between the shape of hidden object surfaces and the sensed light signals under multiple bounces. A model is constructed to recover the three-dimensional shape from diffuse reflections and infer the shape of objects outside the line of sight. The reconstructed model and method are validated using a dataset collected from real-world scenarios.
In this paper, we demonstrated an all fiber laser passively Q-switched by black phosphorus saturable absorber with cylindrical vector beam output. A piece of few-mode fiber Bragg grating was used as the mode-selective output coupler. The repetition rate of the pulse trains increased from 16kHz to 24.9kHz when the pump power tuned from 364mW to 460mW. The maximum pulse energy was 305.2nJ with the shortest pulse duration of 7.5μs under the pump power of 460mW.Both radial polarized and azimuthal polarized pulse output could be achieved by adjusting the polarization controllers. The purity of the cylindrical vector beam output was estimated to be over 95%.
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