Beankondrup9694

We demonstrate a 4,294,967,296-quadrature amplitude modulation (QAM) based Y-00 quantum stream cipher system carrying a 160-Gb/s 16-QAM signal transmitted over 320-km SSMF. The ultra-dense QAM cipher template is realized by an integrated two-segment silicon photonics I/Q modulator.In this paper, a flexible non-orthogonal multiple access (NOMA) based optical orthogonal frequency division multiplexing (OFDM) modulation scheme, called non-orthogonal hybrid optical OFDM (NOHO-OFDM), is proposed to increase the achievable data rate of the visible light communication system with high efficiency. In addition, a receiver with iteratively successive interference cancellation (ISIC) is investigated, which can reduce the estimation error. Then, the achievable data rate of the proposed NOHO-OFDM with the ISIC scheme is analyzed. Experiment results show that the bit error rate of the NOHO-OFDM can be significantly reduced by the proposed ISIC scheme, and the NOHO-OFDM is superior than the orthogonal scheme in terms of data rates. Meanwhile, simulation results show that the achievable data rate region of the proposed NOHO-OFDM scheme is larger than that of the orthogonal counterpart.Three (3) items of errata are submitted for our recently published paper [Opt. Express28, 36505 (2020)10.1364/OE.405566]. One is a clarifying extension to the Fig. 3 caption. Two are typographical corrections. The scientific results and conclusions are unaffected.Pursuing ever-smaller feature size in laser-based lithography is a research topic of vital importance to keep this technique competitive with other micro-/nano-fabrication methods. Features smaller than the diffraction-limited spot size can be obtained by "thresholding", which utilizes the deterministic nature of damage threshold with ultrashort laser pulses and is achieved by precisely tuning pulse energies so that only the central portion of the focal spot produces permanent modification. In this paper, we examine the formulation commonly used to describe thresholding and show that the relationship between feature size (r) and laser fluence (F) is invariant with respect to the nature of laser absorption. Verified by our experiments performed on metal, semiconductor, and dielectric samples, such invariance is used to predict the smallest feature size that can be achieved for different materials in a real-world system.The creation of nanoscale lasers that operate above a coherent threshold is a challenging problem. We propose a way to circumvent this issue using systems in which a strong coupling regime is achieved between the light and the active medium. In the strong coupling regime, energy oscillations take place between the EM field in the cavity and the atoms. Bupivacaine We show that by applying appropriate time modulation to the pumping, it is possible to control these energy oscillations in such a way that coherence in the laser system appears below the lasing threshold. In this approach, the radiation linewidth is two orders of magnitude smaller than the linewidth of a conventional laser for the same photon number. In addition, the second order coherence function of the output radiation is reduced from two to one before the system reaches a positive population inversion. Our results pave the way for the creation of nanoscale sources of coherent radiation that can operate below the lasing threshold.In this paper, we present a model to predict thermal stress-induced birefringence in high energy, high repetition rate diode-pumped YbYAG lasers. The model calculates thermal depolarisation as a function of gain medium geometry, pump power, cooling parameters, and input polarisation state. We show that model predictions are in good agreement with experimental observations carried out on a DiPOLE 100 J, 10 Hz laser amplifier. We show that single-pass depolarisation strongly depends on input polarisation state and pumping parameters. In the absence of any depolarisation compensation scheme, depolarisation varies over a range between 5% and 40%. The strong dependence of thermal stress-induced depolarisation on input polarisation indicates that, in the case of multipass amplifiers, the use of waveplates after every pass can reduce depolarisation losses significantly. We expect that this study will assist in the design and optimisation of YbYAG lasers.III-nitrides based microdisks with the mushroom-type shape are key components for integrated nanophotonic circuits. The air gap undercut in the mushroom-type microdisk is essential for maintaining vertical optical confinement, but this structure is still facing the difficulty of electrical injection. In this work, we demonstrate an electrically injected GaN-based microdisk of such structure. The device is featured with a copper substrate and copper supporting pedestal, through which current can be efficiently injected into the microdisk with low leakage current (less than 10 nA). Bright emission at ∼420 nm was demonstrated from the microdisk under current injection. The copper substrate and supporting pedestal can also extract thermal energy out of the microdisk effectively, and the structure in this work shows a low thermal resistance of ∼788.86 K/W. Low threshold lasing action at ∼405 nm was realized under the optically pumped condition and the threshold energy is ∼35 nJ/pulse. Clear whispering gallery modes were observed and the Q factor is as high as 4504, indicating the high quality of the microdisk cavity. This work is the first step towards low threshold efficient electrically injected microdisk laser with a mushroom-type shape.Detecting seismic events using a fiber-based CW laser interferometer attracts wide attention. To make the detection more effective, we analyze the system's noise level by setting up two vibration detection systems. By changing the fiber length (0∼100 km) and laser noise level, respectively, we detect the minor phase change caused by a 160 µm-fiber-length vibration. Furthermore, we use three indicators, Power Spectral Density, Background Noise Level, and Signal-to-Noise Ratio to analyze the noise level of the whole system. The relation between the system's background noise and corresponding detection result is carried out. This quantitative research can serve as a reference and help people to realize the most efficient vibration detection system.