A compact red-green-blue superluminescent diode module: A novel light source for AR microdisplays

The star simulator was designed to simulate the physical characteristics of real stars. Due to the different color temperatures and magnitudes of different stars, in order to simulate stars more realistically, a starlight source simulation system was required to achieve large-scale high-precision adjustment of color temperature and magnitude. The system consisted of an integrating sphere, light source module, control module and fiber spectrometer to form a closed-loop light source simulation system. In order to ensure the uniformity of the emitted light, a bromotungsten lamp and a variety of monochromatic LED mixed light were used as the light source, and the output brightness of the LED was controlled by constant current driving. The quantum behavior particle swarm algorithm was introduced as the spectrum matching algorithm to solve the LED coefficient ai. As the number of iterations increases, and the value of the fitness function reached the minimum, the simulation error of color temperature and magnitude became smaller. Experimental verification: The range of color temperature was 3 000, 4 300, 5 500, 6 500, 7 600, 20 000 K, the color temperature matching error was better than ±10%; the range of simulated magnitude was +2-+8.5 Mi, and the magnitude matching error was better than ±6%.

The three primary-color LED light source modules produce a color within the gamut space by the Pulse-Width-Modulation (PWM) duty cycle. In a host control multiple LED module system, due to the specificity of the three primary-color LED light sources, different light source modules cannot generate the same target color coordinates according to the same set of duty ratio data, thereby causing a color inconsistency in each light source. This paper proposes an algorithm for personalizing the Red-Green-Blue (RGB) values by using the three primary-color coordinates obtained by feedbacks. Through extensive experiments, the algorithm can effectively reduce the color difference produced by different LED lamp beads. The algorithm has a small amount of calculation and can be easily implemented in practical devices.

At Olkaria II power plant located in Kenya, the brine from the separator is re-injected back into the ground. This study analyzes a flash geothermal-solar hybrid cycle using the working fluids n-butane, n-pentane, cyclopentane, hexamethyldisiloxane and toluene in order to utilize the brine. The studied working fluids have no potential to deplete the ozone or cause global warming. The working fluids were analyzed in terms of net power output and pump power required. This was done by heating Therminol VP-1 fluid to a maximum temperature of 400 °C using the parabolic trough solar collector and varying the working fluids mass flow rate, Therminol VP-1 flow rate and pressure, and the brine pressure and flow rate. They were varied to investigate their effect on the power output of the Organic Rankine Cycle. The working fluid with higher net power output was selected as a suitable working fluid for the hybrid cycle. The selected working fluid was used to determine the average hourly power output in each month of the hybrid system using the irradiance of Olkaria II power station. N-butane showed the best results in net power output hence it was selected as a suitable working fluid as compared to the other working fluids. When the hybrid system was analyzed using n-butane to obtain the hourly average power output in each month, the results revealed that the month of February has the highest hourly average power output where the Steam Turbine has an average hourly power output of 10.48 MW and Binary Turbine net power output of 18.56 MW. The minimum average hourly power output was obtained in the month of June where the Steam Turbine has an average hourly power output of 9.08 MW and Binary Turbine net power output of 16.88 MW.

The saliency feature is a key factor in achieving vision-based tracking for multi-UAV control. However, due to the complex and variable environments encountered during multi-UAV operations—such as changes in lighting conditions and scale variations—the UAV’s visual features may degrade, especially under high-speed movement, ultimately resulting in failure of the vision tracking task and reducing the stability and robustness of swarm flight. Therefore, this paper proposes an adaptive active light source system based on light intensity matching to address the issue of visual feature loss caused by environmental light intensity and scale variations in multi-UAV collaborative navigation. The system consists of three components: an environment sensing and control module, a variable active light source module, and a light source power module. This paper first designs the overall framework of the active light source system, detailing the functions of each module and their collaborative working principles. Furthermore, optimization experiments are conducted on the variable active light source module. By comparing the recognition effects of the variable active light source module under different parameters, the best configuration is selected. In addition, to improve the robustness of the active light source system under different lighting conditions, this paper also constructs a light source color matching model based on light intensity matching. By collecting and comparing visible light images of different color light sources under various intensities and constructing the light intensity matching model using the comprehensive peak signal-to-noise ratio parameter, the model is optimized to ensure the best vision tracking performance under different lighting conditions. Finally, to validate the effectiveness of the proposed active light source system, quantitative and qualitative recognition comparison experiments were conducted in eight different scenarios with UAVs equipped with active light sources. The experimental results show that the UAV equipped with an active light source has improved the recall of yoloV7 and RT-DETR recognition algorithms by 30% and 29.6%, the mAP50 by 21% and 19.5%, and the recognition accuracy by 13.1% and 13.6, respectively. Qualitative experiments also demonstrated that the active light source effectively improved the recognition success rate under low lighting conditions. Extensive qualitative and quantitative experiments confirm that the UAV active light source system based on light intensity matching proposed in this paper effectively enhances the effectiveness and robustness of vision-based tracking for multi-UAVs, particularly in complex and variable environments. This research provides an efficient and computationally effective solution for vision-based multi-UAV systems, further enhancing the visual tracking capabilities of multi-UAVs under complex conditions.

Design and analysis of a high-intensity LED lighting module for underwater illumination

The demand for high-power, high-density VCSEL light sources in applications such as space, artificial intelligence, silicon photonics, and autonomous vehicles is steadily increasing. VCSEL chips are epitaxially grown on GaAs substrates and then packaged by attaching them to a mounting bracket using high-temperature-resistant adhesives. This issue limits the VCSEL’s output power, and restricts its application range. We propose first removing the VCSEL epitaxial layer from the GaAs substrate and transferring it to a CuW substrate. The VCSEL chip is then mounted on an AlN substrate using a metal eutectic bonding technique. The results indicate that bonding 36 VCSELs with a wavelength of 840 nm to CuW chips and mounting them onto an AlN substrate to form an array achieved voltage of 8.59 V and a driving current of 18 A. The output optical power reached 57.68 W, with a reduced packaging thermal resistance of 0.232 K/W.

This paper describes a monolithically integrated light source module of a high‐speed/low‐driving voltage multiquantum well (MQW) optical modulator and DFB laser for 1.55‐μm applications. This paper investigates: (1) device structure suitable for growing high‐quality crystal, (2) efficient performance due to adoption of a strained InGaAsP MQW, (3) reduction of device capacitance using polyimide at the electrodes of the optical modulator, and (4) realization of a monolithically integrated module using lens coupling.In the test device, the oscillation threshold current was below 15 mA, the extinction ratio was over 20 dB when the bias voltage was −2 V, the frequency band was 15 GHz (−3 dB), and the optical power coupled to an optical fiber was 2.5 mW. Optical modulation at 15 Gb/s was carried out at a driving voltage of 1 Vp‐p. When this device was used under 2 Gb/s high‐speed modulation using a driving voltage of 2 Vp‐p for 100‐km transmission, the minimum optical power sensitivity was −23 dBm and the power penalty was 1 dB. This result indicates that this monolithically integrated optical source is suitable for large‐capacity/long‐distance optical communication.

Fabrication of 365 nm Wavelength High Transmittance Silicone Resin TIR Lens and High Directivity Light Source Module for Exposure System

Diode Lasers (LD) and light emitting diodes (LEDS) have been used for fluorescence imaging due to their low cost and wavelength varieties. The fluorescence Imaging has recently been developed as a nonde-structive method for fruit and vegetable quality assessments. This research was aimed to study the potential use of both light sources in fluorescence imaging techniques for grading palm oil fresh fruit bunches in attempt to develop a laser based grading system. The system consisted of a 650 nm LD and a 680 nm LED with the same 5 mW output power. and a monochrome CMOS camera with a camera lens, and a color filter. The filter used to obtain the fluorescene intensity was an orange filter. The samples were Tenera varieties of lonsum loosed palm oil fresh fruits with 4 ripeness categories determined by an experienced harvester. The categories were underripe (f0), ripe 1 (f1), ripe 2 (f2) and ripe 3(f3), each with 3 duplicates.The recorded images of the loosed fruits were analyzed using imageJ software, and further compared.The result showed that the highest fluorescence intensities represented by the gray values of the images were obtained from the underripe (f0) fruits, followed by the ripe 2 (f2), ripe 3(f3), and, ripe 1(f1) fruits, for both light sources.The intensity levels ob-tained using LD were higher by 75.32a.u for underripe (f0), 52.35 a.u for ripe 1(f1), 57.18a.u for ripe 2(f2), and 55.11 a.u for ripe 3(f3) than those resulted from LEDS by 24.57a.u for underripe(f0), 19.71 a.ufor ripe 1(f1), 22.91 a.ufor ripe 2(f2), 21.78 a.u.for ripe 3(f3). There are two reasons for higher results obtained user laser, due to their differencesin wavelength, and beam shape.

Lasing and self-pumped optical parametric oscillation (self-OPO) are achieved in a high-Q whispering-gallery-mode micro-resonator, made of neodymium-doped lithium niobate. A laser process providing 5 mW output power at 1.08 μm wavelength is sufficient to pump a self-OPO process within the same high-Q cavity. At 6 mW lasing output power, the sum of signal and idler output powers exceeds 1.2 mW. The wavelength of the generated light ranges from 1.5 to 3.8 μm. Phase matching is provided by a radial quasi-phase-matching structure, which is generated by a current-controlled calligraphic poling technique. To the best of our knowledge, this is the first demonstration of a quasi-phase-matched self-pumped nonlinear optical process in a micro-resonator, as well as the first self-OPO in a micro-resonator. The concept bears the potential for a highly integrated and wavelength-tunable coherent light source at low cost.

High-brightness tapered lasers and amplifiers at 670 nm with output powers up to 1 W and nearly diffraction limited beam quality were realised. The devices consist of a 750 &mgr;m long straight section and a 1250 &mgr;m long tapered section. Devices with a taper angle of 2°, 3° and 4° were manufactured. The material quality was studied in a long-term test for ridge-waveguide lasers. Devices with 7.5 &mgr;m ridge width show reliable operation at 100 mW output power over more than 10000 h. At a temperature of 15°C a tapered lasers with an angle of 4° reached an output power of 1 W at a current of 2.1 A. The highest conversion efficiency for this device was 24%, the peak wavelength of the emission was 668 nm and the spectral width was smaller than 0.2 nm. The beam propagation factor was M² = 1.7 (1/e²) and M² = 3.0 (second moments). At 500 mW output power, master-oscillator power-amplifier (MOPA) devices showed also a nearly diffraction limited beam quality with M² < 1.5 and reliable operation with degradation rates as low as 7x10^-6 h^-1 over 1200 h. The spectral line-width in this arrangement is determined by the master oscillator and is suitable for high-resolution spectroscopy.

Summary form only given. A 95 GHz gyrotron capable of generating CW power levels in excess of 2 MW is currently under development at CPI. The gyrotron makes use of a single-anode electron gun that produces a 90-kV, 75-A electron beam for interaction with the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> , <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> , <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> cavity mode. Microwave power produced in the interaction cavity is transformed into a fundamental Gaussian beam using an internal waveguide launcher and three focusing and phase-correcting mirrors. The Gaussian beam exits the tube through an edge-cooled chemical-vapor-deposition (CVD) diamond window. The spent electron beam is dissipated in a 40.6-cm diameter collector fabricated from a strengthened copper alloy. The collector nominally operates at a depressed voltage 61 kV above the cathode potential to minimize the amount of power absorbed and improve efficiency.In the first series of experiments, a maximum output power level of 1.45 MW was obtained using a 61 kV cathode voltage, 90 kV total accelerating voltage, and 75 A beam current. Interaction and total output efficiencies were 21% and 32%, respectively. At a beam current of 40 A and the same voltage settings, an output power of 1.08 MW was measured for an interaction efficiency of 30% and a total output efficiency of 44%. Experimental evidence indicated that an oscillation in the beam tunnel region just prior to the interaction cavity was a likely cause of the lower than expected efficiency and output power at higher beam currents. In an attempt to alleviate the detrimental effects of the oscillation, a new beam tunnel was installed on the gyrotron. No other major changes to the gyrotron were made. In a second series of tests, a maximum, output power of 1.72 MW was obtained with a cathode voltage of 70 kV, an accelerating voltage of 93 kV and a beam current of 75 A. The interaction efficiency at this point was 25% and the total output efficiency was 33%. At 45 Abeam current, an accelerating voltage of 90 kV, and a collector voltage of 61 kV, an output power of 1.40 MW was obtained with an interaction efficiency of 35% and a total output efficiency of 51%. It appears that the presence of beam tunnel power still degrades the interaction efficiency at higher values of beam current, but there has been a marked improvement between the first and second series of tests, where the maximum achievable power has increased from 1.45 MW to 1.72. The operation at 1.4 MW output power with over 50% efficiency is also an important achievement.

High-efficiency and high-power operation have been demonstrated for blue GaN-based vertical-cavity surface-emitting lasers (VCSELs) with AlInN/GaN distributed Bragg reflectors. The high-efficiency performance was achieved by introducing a novel SiO2-buried lateral index guide and adjusting the front mirror reflectivity. Lateral optical confinement has been shown to greatly lower the otherwise significant loss of transverse radiation exhibited by typical VCSELs based on GaN. Employing a long (10λ) cavity can also enhance the output power, by lowering the thermal resistance of the VCSEL and increasing the operating current associated with thermal rollover. This modification, in conjunction with optimized front mirror reflectivity and a buried SiO2 lateral index guide, results in a blue VCSEL (in the continuous wave mode with an 8 μm aperture at 20 °C) having a superior differential quantum efficiency value of 31% and an enhanced 15.7 mW output power. This unit also exhibits a relatively high output power of 2.7 mW at temperatures as high as 110 °C. Finally, a 5.5 μm aperture VCSEL was found to generate a narrow divergence (5.1°) single-lobe far field pattern when operating at an output power of approximately 5 mW.

Laser operation near 1.06 μm by diode-pumped Nd:(Lu x Gd 1-x ) 3 Ga 5 O 12 (Nd:LGGG, with x = 0.1) and Gd 3 Al x Ga 5-x O 12 (GAGG, with x = 1) disordered crystals has been investigated. Cw oscillation with a slope efficiency as high as 61 % and 230 mW output power was achieved with 400 mW absorbed power from a 1-W laser diode in Nd:LGGG. Under the same pumping conditions cw oscillation with a slope efficiency as high as 55% and 255 mW output power was achieved with 500 mW absorbed power in Nd:GAGG. Stable passive mode-locking with single- or multi-wavelength spectrum was obtained with a semiconductor saturable absorber mirror (SAM) and a single-prism, dispersion-compensated cavity with both the samples. Fourier-limited pulses with duration = 4 - 9 ps and output power ≈ 40 mW were generated at three well-defined laser transitions in the range 1062-1067 nm with ND:GLGG. Two-color mode-locking regime well described by Fourier-limited synchronized pulses with duration = 3.7 and 5.9 ps and output power ≈ 65 mW, with wavelength separation of 1.3 nm around 1062 nm was obtained with Nd:GAGG.

This thesis researches the design of transceiver front-end RF amplifiers for Bluetooth applications in GPDK 45 nm CMOS technology. The target of the design was to minimize the transceiver's power consumption while achieving the best device operating performances. The design of a band-pass low noise amplifier (LNA) used for the receiver and the design of a power amplifier (PA) used for the transmitter were presented. Both amplifiers were designed in 45 nm CMOS technology with a DC supply voltage under 1.2 V to meet Bluetooth specifications at 2.45 GHz operating frequency. The LNA was designed to achieve a minimum small signal gain of at least 15 dB10 with a NF less than 2 dB10 and a reasonable input range for linearity at 1 mW operating power consumption. The PA was designed based on class E switching power amplifier configuration to achieve a minimum of 40% drain efficiency for 100 mW (Bluetooth Class 1) output power. Research on low power high performance Bluetooth device front-end RF amplifiers was conducted through studies of wireless communication modulation schemes, impedance matching networks, and trade-offs between performance parameters. In summation, this thesis searched for, explored, and analyzed possible methodologies that could be used to design RF CMOS amplifiers of Bluetooth applications.