Pixelated non-volatile programmable photonic integrated circuits with 20-level intermediate states

Multi-level programmable photonic integrated circuits(PICs)and optical metasurfaces have gained widespread attention in many fields,such as neuromorphic photonics,opticalcommunications,and quantum information.In this paper,we propose pixelated programmable Si_(3)N_(4)PICs with record-high 20-level intermediate states at 785 nm wavelength.Such flexibility in phase or amplitude modulation is achieved by a programmable Sb_(2)S_(3)matrix,the footprint of whose elements can be as small as 1.2μm,limited only by the optical diffraction limit of anin-house developed pulsed laser writing system.We believe our work lays the foundation for laser-writing ultra-high-level(20 levels and even more)programmable photonic systems and metasurfaces based on phase change materials,which could catalyze diverse applications such as programmable neuromorphic photonics,biosensing,optical computing,photonic quantum computing,and reconfigurable metasurfaces.

Implementing a vector surveillanceresponse system for chagas disease control:a 4-year field trial in Nicaragua

Background:Chagas disease is one of the neglected tropical diseases(NTDs).International goals for its control involve elimination of vector-borne transmission.Central American countries face challenges in establishing sustainable vector control programmes,since the main vector,Triatoma dimidiata,cannot be eliminated.In 2012,the Ministry of Health in Nicaragua started a field test of a vector surveillance-response system to control domestic vector infestation.This paper reports the main findings from this pilot study.Methods:This study was carried out from 2012 to 2015 in the Municipality of Totogalpa.The Japan International Cooperation Agency provided technical cooperation in designing and monitoring the surveillance-response system until 2014.This system involved 1)vector reports by householders to health facilities,2)data analysis and planning of responses at the municipal health centre and 3)house visits or insecticide spraying by health personnel as a response.We registered all vector reports and responses in a digital database.The collected data were used to describe and analyse the system performance in terms of amount of vector reports as well as rates and timeliness of responses.Results:During the study period,T.dimidiata was reported 396 times.Spatiotemporal analysis identified some high-risk clusters.All houses reported to be infested were visited by health personnel in 2013 and this response rate dropped to 39%in 2015.Rates of insecticide spraying rose above 80%in 2013 but no spraying was carried out in the following 2 years.The timeliness of house visits improved significantly after the responsibility was transferred from a vector control technician to primary health care staff.Conclusions:We argue that the proposed vector surveillance-response system is workable within the resourceconstrained health system in Nicaragua.Integration to the primary health care services was a key to improve the system performance.Continual efforts are necessary to keep adapting the surveillance-response system to the dynamic health systems.We also discuss that the goal of eliminating vector-borne transmission remains unachievable.This paper provides lessons not only for Chagas disease control in Central America,but also for control efforts for other NTDs that need a sustainable surveillance-response system to support elimination.

A 3.8 GHz programmable gain amplifier with a 0.1 dB gain step

A broadband programmable gain amplifier（PGA） with a small gain step and low gain error has been designed in 0.13 m CMOS technology. The PGA was implemented with open-loop architecture to provide wide bandwidth. A two-stage gain control method, which consists of a resistor ladder attenuator and an active fine gain control stage, provides the small gain step. A look-up table based gain control method is introduced in the fine gain control stage to lower the gain error.The proposedPGAshows a decibel-linear variable gainfrom4 to20 dB with a gain step of 0.1 dB and a gain error less than˙0.05 dB. The 3-dB bandwidth and maximum IIP3 are 3.8 GHz and 17 dBm, respectively.