Large-scale photonic switches are essential devices for energy-and cost-efficient optical communication networks in cloud and data-intensive computing. Silicon photonics is an attractive platform for high-density photonic integrated circuits with low manufacturing costs through the leveraging of existing advanced complementary metal-oxidesemiconductor processes. Many optical components such as lasers, modulators, splitters, and photodetectors have been successfully integrated on silicon; however, the quest for large-scale silicon photonic switches has remained elusive. Previous silicon photonic switches made of cascaded 1 × 2 or 2 × 2 building blocks have a limited port count (≤8 × 8) or excessive optical losses (>15 dB). Here, we present a 64 × 64 digital silicon photonic switch with a low on-chip insertion loss (3.7 dB) and broadband operation (300 nm). The measured switching time is 0.91 μs, and the extinction ratio is larger than 60 dB. The matrix switch with 4096 microelectromechanical-systems-actuated vertical adiabatic couplers has been integrated on a 8.6 mm × 8.6 mm chip. To our knowledge this is the largest monolithic switch, and the largest silicon photonic integrated circuit, reported to date. The passive matrix architecture of our switch is fundamentally more scalable than that of multistage switches.

Fast optical circuit switches (OCSs) with high port count offer reconfigurable bandwidth in optical networks and have the potential to significantly increase the performance and efficiency of modern datacenters. In this paper, we report on a new type of integrated OCS that combines silicon photonics with MEMS actuation. The switch is built on a 50 × 50 passive crossbar network with very low optical loss (0.04 dB/crossing). Efficient switching is achieved by a pair of directional couplers with moving waveguides and an actuation voltage of 14 V. 2500 MEMS-actuated directional coupler switches have been integrated with the crossbar network to form a strictly nonblocking 50 × 50 OCS on a 9 mm × 9 mm chip. The measured switching time is 2.5 μs, and the extinction ratio is 26 dB. To our knowledge, this is the largest silicon photonic switch reported to date. The switch architecture is highly scalable because the light travels through only one active switching element, regardless of the size of the switch.

Background Demographic, work environmental, and psychosocial features are associated with mental health of healthcare professionals at pandemic frontline. The current study aimed to find predictors of mental health for public health doctors from working experiences at frontline of COVID-19 pandemic. Methods With first-come and first-served manner, 350 public health doctors with experiences of work at COVID-19 frontline participated online survey on August 2020. Mental health was defined using the total scores of the Patient Health Questionnaire-9, the Generalized Anxiety Disorder-7, the Perceived Stress Scale, and the Stanford Presenteeism Scale-6. Multivariate logistic regression models of mental health with lowest Akaike Information Criterion were determined among all combinations of working environments, perceived threats and satisfaction at frontline, and demographics that were significant (P < 0.05) in the univariate logistic regression. Results Perceived distress, lowered self-efficacy at work, anxiety, and depressive mood were reported by 45.7, 34.6, 11.4, and 15.1% of respondents, respectively. Predictors of poor mental health found in the multivariate logistic regression analyses were environmental (insufficient personal protective equipment, workplace of screening center, prolonged workhours) and psychosocial (fear of infection and death, social stigma and rejection) aspects of working experiences at frontline. Satisfaction of monetary compensation and proactive coping (acceptance and willingness to volunteer at frontline) were predictive of better mental health. Conclusions Sufficient supply of personal protective equipment and training on infection prevention at frontline, proper workhours and satisfactory monetary compensation, and psychological supports are required for better mental health of public health doctors at frontline of COVID-19 pandemic.

No abstract

No abstract