A downshifting Eu 3+ doped glass embedded with concave pyramid microstructure to improve the efficiency of silicon solar cell

Abstract(#br)The average photoelectric conversion efficiency (PCE) of a bare mono crystalline silicon solar cell is 14.71 (±0.03)% under AM1.5. It decreases to 14.20 (±0.005)% when covering an un-doped flat glass on the solar cell, and it goes down to 14.10 (±0.005)% by using a 5 wt% Eu 3+ doped glass. The absorptions of the Eu 3+ doped CPM glass one-to-one match the excitation spectrum at 362, 381, 393, 400, 413 and 464 nm, which are related to the transitions of 7 F 0 →( 5 D 4 , 5 G 2 , 5 L 6 , 5 D 3 ), 7 F 1 → 5 D 3 , and 7 F 0 → 5 D 2 , respectively. In addition, a concave pyramid microstructure (CPM) is embedded in the glass surface to increase light transmittance. The average PCE increases to 14.61 (±0.07)% when a 5 wt% Eu 3+ doped CPM glass covers on the silicon solar cell. Comparing to the un-doped flat glass, a net increase of the PCE is 0.41%, where the 0.16% increment of PCE is from the lighting trapping of the CPM structure, and the downshifting of near ultraviolet (NUV) light by Eu 3+ ion donates the other 0.25% increment. It confirms that the as-prepared Eu 3+ doped CPM glass has a good downshifting and antireflection function

Near ultraviolet excited white light emitting diode (WLED) based on the blue LiCaPO 4 :Eu 2+ phosphor

Abstract(#br)One near ultraviolet (NUV) chip coated with tricolor phosphors to fabricate the white light emitting diode (WLED) has been attractive widely. In this paper, the blue emitting LiCaPO 4 :Eu 2+ , together with the red CaSiAlN 3 : Eu 2+ and the green (Sr, Ba)SiO 4 : Eu 2+ phosphor, is selected as the tricolor components for the NUV excited WLED preparation. The as-prepared WLED exhibits good luminescent performances with the color rendering index (Ra) of 88.6, the correlation color temperature of 3351 K, the lumen efficiency of 77.05 lm/W, and the color coordinates located at (0.4399, 0.4389). It is worth mentioning that the blue-light of the warm WLED succeeds to keep away from the hazard zone centered at 450 nm. Furthermore, a full spectrum warm WLED with the color rendering index (CRI) of 95.8 is fabricated by adding the fourth component as the Sr 5 (PO 4 ) 3 Cl:Eu 2+ phosphor. The prepared full spectrum WLED achieves the performance index of museum lighting

Sensitive Infrared Signal Detection by Upconversion Technique

We demonstrated upconversion assisted detection of a 2.05-micron signal by sum frequency generation to generate a 700-nm light using a bulk periodically poled lithium niobate crystal. The achieved 94% intrinsic upconversion efficiency and 22.58% overall detection efficiency at a pW level of 2.05 micron pave the path to detect extremely weak infrared (IR) signals for remote sensing applications

Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications

A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW

Search for Continuous Gravitational-wave Signals in Pulsar Timing Residuals: A New Scalable Approach with Diffusive Nested Sampling

Detecting continuous nanohertz gravitational waves (GWs) generated by individual close binaries of supermassive black holes (CB-SMBHs) is one of the primary objectives of pulsar timing arrays (PTAs). The detection sensitivity is slated to increase significantly as the number of well-timed millisecond pulsars will increase by more than an order of magnitude with the advent of next-generation radio telescopes. Currently, the Bayesian analysis pipeline using parallel tempering Markov Chain Monte Carlo has been applied in multiple studies for CB-SMBH searches, but it may be challenged by the high dimensionality of the parameter space for future large-scale PTAs. One solution is to reduce the dimensionality by maximizing or marginalizing over uninformative parameters semianalytically, but it is not clear whether this approach can be extended to more complex signal models without making overly simplified assumptions. Recently, the method of diffusive nested (DNest) sampling has shown capability in coping with high dimensionality and multimodality effectively in Bayesian analysis. In this paper, we apply DNest to search for continuous GWs in simulated pulsar timing residuals and find that it performs well in terms of accuracy, robustness, and efficiency for a PTA including pulsars. DNest also allows a simultaneous search of multiple sources elegantly, which demonstrates its scalability and general applicability. Our results show that it is convenient and also highly beneficial to include DNest in current toolboxes of PTA analysis

Search for Continuous Gravitational-wave Signals in Pulsar Timing Residuals: A New Scalable Approach with Diffusive Nested Sampling

Detecting continuous nanohertz gravitational waves (GWs) generated by individual close binaries of supermassive black holes (CB-SMBHs) is one of the primary objectives of pulsar timing arrays (PTAs). The detection sensitivity is slated to increase significantly as the number of well-timed millisecond pulsars will increase by more than an order of magnitude with the advent of next-generation radio telescopes. Currently, the Bayesian analysis pipeline using parallel tempering Markov Chain Monte Carlo has been applied in multiple studies for CB-SMBH searches, but it may be challenged by the high dimensionality of the parameter space for future large-scale PTAs. One solution is to reduce the dimensionality by maximizing or marginalizing over uninformative parameters semianalytically, but it is not clear whether this approach can be extended to more complex signal models without making overly simplified assumptions. Recently, the method of diffusive nested (DNest) sampling has shown capability in coping with high dimensionality and multimodality effectively in Bayesian analysis. In this paper, we apply DNest to search for continuous GWs in simulated pulsar timing residuals and find that it performs well in terms of accuracy, robustness, and efficiency for a PTA including pulsars. DNest also allows a simultaneous search of multiple sources elegantly, which demonstrates its scalability and general applicability. Our results show that it is convenient and also highly beneficial to include DNest in current toolboxes of PTA analysis

Optimization of A 2-Micron Laser Frequency Stabilization System for a Double-Pulse CO2 Differential Absorption Lidar

A carbon dioxide (CO2) Differential Absorption Lidar (DIAL) for accurate CO2 concentration measurement requires a frequency locking system to achieve high frequency locking precision and stability. We describe the frequency locking system utilizing Frequency Modulation (FM), Phase Sensitive Detection (PSD), and Proportional Integration Derivative (PID) feedback servo loop, and report the optimization of the sensitivity of the system for the feed back loop based on the characteristics of a variable path-length CO2 gas cell. The CO2 gas cell is characterized with HITRAN database (2004). The method can be applied for any other frequency locking systems referring to gas absorption line

One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser

Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality

Development of a Coherent Differential Absorption Lidar for Range Resolved Atmospheric CO2 Measurements

A pulsed, 2-m coherent Differential Absorption Lidar (DIAL) / Integrated Path Differential Absorption (IPDA) transceiver, developed under the Laser Risk Reduction Program (LRRP) at NASA, is integrated into a fully functional lidar instrument. This instrument will measure atmospheric CO2 profiles (by DIAL) initially from a ground platform, and then be prepared for aircraft installation to measure the atmospheric CO2 column densities in the atmospheric boundary layer (ABL) and lower troposphere. The airborne prototype CO2 lidar can measure atmospheric CO2 column density in a range bin of 1km with better than 1.5% precision at horizontal resolution of less than 50km. It can provide the image of the pooling of CO2 in lowlying areas and performs nighttime mass balance measurements at landscape scale. This sensor is unique in its capability to study the vertical ABL-free troposphere exchange of CO2 directly. It will allow the investigators to pursue subsequent in science-driven deployments, and provides a unique tool for Active Sensing of CO2 Emissions over Night, Days, and Seasons (ASCENDS) validation that was strongly advocated in the recent ASCENDS Workshop