Non-resonant power-efficient directional Nd:YAG ceramic laser using a scattering cavity

Abstract

Non-resonant lasers exhibit the potential for stable and consistent narrowband light sources. Furthermore, non-resonant lasers do not require well-defined optics, and thus has considerably diversified the available types of laser gain materials including powders, films, and turbid ceramics. Despite these intrinsic advantages, the practical applications of non-resonant lasers have been limited so far, mainly because of their low power efficiency and omnidirectional emission. To overcome these limitations, here we propose a light trap design for non-resonant lasers based on a spherical scattering cavity with a small entrance. Using a porous Nd3+:YAG ceramic, directional laser emission could be observed with significant enhancements in the slope efficiency and linewidth (down to 32 pm). A theoretical model is also developed to describe and predict the operation characteristics of proposed non-resonant laser.

Rapid Review of Social Contact Patterns During the COVID-19 Pandemic

“…Several studies estimated R t during the post-relaxation period. The median estimates for R t increased to above 1 in the USA, 35 Belgium, 34 and in online reports from the UK 47 but remained below 1 in China. 40 , 41…”

“…Eleven 32 – 42 studies collected data during the initial mitigation period between February and May 2020 with the most stringent physical distancing measures (Figure 2 ) with seven 32 – 34 , 36 – 39 collecting data during nationally declared lockdown and four 35 , 40 – 42 during regional lockdown. Five 33 – 35 , 37 , 41 studies also collected additional data when interventions were relaxed (April and May for China and between May and September for other settings) and one 43 study collected data exclusively during the period of relaxation. 43 Policies in place during data collection period were similar but varied (eTable 4; http://links.lww.com/EDE/B848 and eFigure 7; http://links.lww.com/EDE/B848 ) as did the epidemic situation (eFigure 1; http://links.lww.com/EDE/B848 ).…”

“…The majority of studies were one-time cross-sectional surveys, 33 , 36 , 38 – 42 one was longitudinal (a cohort of participants repeatedly responded to surveys over time), 34 and four were repeated cross-sectional surveys (surveys were repeated over time with different participants). 32 , 35 , 37 , 43 The majority (7/12) used online surveys to recruit participants and collect contact data, while the remaining studies were conducted using phone-based surveys. Sample sizes ranged from 200 for the study conducted in Nairobi, Kenya 42 to approximately 54,000 for one study conducted across several countries.…”

Zenneck surface wave interconnect with encircle routing for effective inter chip communication

“…Both methods have advantages in replacing the copper traces by means of power dissipation, interference, and efficiency. 4 However, wireless communication meets several issues with respect to channel bandwidth and free space spreading loss. 5,6 Molecular absorption attenuation at high frequency bands even electric field decay rate for this sort of communication expressed as shown below:…”

Enhancing sensitivity in absorption spectroscopy using a scattering cavity

“…Multiple light scattering has been exploited to increase the OPL and overcome the limitations of conventional optical elements [18], including superlens [19], temperature [20], pressure sensing [21], wavelength meters [22], fiber-based spectrometers [23], and nonresonant lasers [24]. Recently, Martin et al [25] suggested multiple scattering for enhancing the sensitivity of absorption spectroscopy.…”