Bifunctional gas sensor based on Bi2S3/SnS2 heterostructures with improved selectivity through visible light modulation

Effective monitoring of hazardous gases at room-temperature is extremely indispensable in the “Internet of things” application; however, developing bifunctional gas sensors for the advanced sensing platform still remains a challenge....

Graphene on Silicon Photonics: Light Modulation and Detection for Cutting-Edge Communication Technologies

Graphene—a two-dimensional allotrope of carbon in a single-layer honeycomb lattice nanostructure—has several distinctive optoelectronic properties that are highly desirable in advanced optical communication systems. Meanwhile, silicon photonics is a promising solution for the next-generation integrated photonics, owing to its low cost, low propagation loss and compatibility with CMOS fabrication processes. Unfortunately, silicon’s photodetection responsivity and operation bandwidth are intrinsically limited by its material characteristics. Graphene, with its extraordinary optoelectronic properties has been widely applied in silicon photonics to break this performance bottleneck, with significant progress reported. In this review, we focus on the application of graphene in high-performance silicon photonic devices, including modulators and photodetectors. Moreover, we explore the trend of development and discuss the future challenges of silicon-graphene hybrid photonic devices.

SENSITIVITY ANALYSIS ON THE EFFECT OF MEASUREMENT NOISE AND SAMPLING FREQUENCY ON THE CALCULATION OF THE TEMPORAL LIGHT ARTEFACTS

Temporal light modulation (TLM) and the resulting temporal light artefacts (TLA) can cause problems with health and wellbeing for users of lighting products. Therefore, TLM has to be measured accurately and repeatably. This study investigates important factors influencing the measurement uncertainty of TLM measurements. The study shows how measurement uncertainty on central TLM parameters can have a significant effect on the calculation of TLA. Specifically, we show a linear relationship between DC offset and the expected error. Further we show severe effects of random noise on PstLM on certain waveforms. And lastly, we show a curious effect related to SVM of pulse width modulated signals and the measurement sampling frequency.

RISKS IN THE VISUAL ENVIRONMENT SUCH AS GLARE, ILLUMINANCE AND LUMINANCE RATIO - RISK ASSESSMENTS MADE WITH VISUAL ERGONOMICS RISK ASSESSMENT METHOD, VERAM– A DESCRIPTIVE PAPER

The visual environment has an impact on subjective strain and headaches. A visual ergonomics risk assessment method, VERAM, was used on 217 workplaces, and consists of both of a subjective questionnaire and an objective risk assessment, the latter risks are presented in this paper. The risk for daylight was assessed to be yellow (moderate risk) or red (high risk) at 53% of the workplaces and the risk for glare was yellow or red at 66%. The assessment of the lighting design showed a yellow or red risk at 44% of the workplaces and the illuminance was assessed to be insufficient at 49% of the workplaces. Flicker or TLM (temporal light modulation) was assessed to be a problem among 33%. These results show that the design of the visual environment is in most cases not performed in a satisfying way. The visual environment is essential to increase wellbeing, health and performance.

DEFINITION MODIFICATIONS FOR TEMPORAL LIGHT MODULATION (“FLICKER”)

Terminology and concepts for temporal light modulation (TLM), commonly known as “flicker,” are defined and used inconsistently, even among researchers. A literature review by the authors has identified multiple meanings for multiple terms, so it is critical that a reader be able to translate from a single article’s definitions to a more universal set. A simple example is that “flicker” is used interchangeably as the stimulus as well as the response to the stimulus, as well as the direct visual response for a specific range of modulation frequencies. This paper endeavours to clarify communication among stakeholders so that effective metrics can be developed to limit unwanted physiological, psychological, behavioural, and cognitive responses to TLM. Changes to the CIE International Lighting Vocabulary are recommended.

FACILITY FOR CALIBRATION OF PHOTOMETERS FOR TEMPORAL LIGHT MODULATION

We developed a facility for calibration of TLM (temporal light modulation) photometers. The facility is based on a laser-fed reference source, of which the radiance can be modulated with an acousto-optic modulator (AOM). A system of photodiodes, amplifiers, and an analog-to-digital converter (ADC) is used to sample the temporally modulated radiance of the source. With the facility a TLM photometer was calibrated for display contrast ratio RMS (root mean square) with an absolute combined standard uncertainty of 0,037 %. In addition, the facility has been characterised with the aim of measuring flicker and stroboscopic effect, considering the Ecodesign ‘Single Lighting Regulation’. The frequency response of the facility shows to be sufficient to accommodate measurements of flicker and the stroboscopic effect.