Phutung Research Institute

Research

Publications

25 publications from Phutung Research Institute — journal articles, conference proceedings and preprints, 2016–2025.

25 results · showing 13–24 · page 2 of 3

RealtimeWAS: A Low-Cost, Portable Device for Real-time Detection of Fecal Contamination in Drinking Water

Prashant Waiba, Raj Bakhunchhe, Asim Maharjan, Rajin Pradhan, Sharad Timilsina, Rijan Maharjan , Thomas F Krauss and Ashim Dhakal

Frontiers in Optics + Laser Science Conference 2023

We present realtimeWAS : a low-cost, portable, and reagent-free device to detect fecal contamination in water using real-time fluorescence measurement. The device returns quantitative (via display) and semi-quantitative (via LED indicators) measures of water…

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Upconversion of infrared light by graphitic micro-particles due to photo-induced structural modification

Rohin Sharma, Nishma Bhattarai, Rijan Maharjan, Lilia M. Woods, Nirajan Ojha, Ashim Dhakal

Advanced Photonics Research

Recent reports of upconversion and white light emission from graphitic particles warrant an explanation of the physics behind the process. We offer a model, wherein the upconversion is facilitated by photo-induced electronic structure modification allowing…

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Low-cost Polymerase Chain Reaction (PCR) Technology for the Detection of DNA Amplicons

Prashant Waiba, Pravin Bhattarai, Mitesh Shrestha, Ashim Dhakal

Presented in International Conference on Bioscience and Biotechnology, Suraha, Nepal 2022

The design of Pagoda PCR is gleaned from the OpenPCR concept. The reliability of PCR results is dependent on how precisely the intended amplicons are amplified during the thermocycling process [1]. In Pagoda PCR, a single Peltier module is used with a…

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A Low-cost Fresnel Lens Fluorometer to Detect Fecal Contamination in Drinking Water in Realtime

Sanket Bohora, Kezheng Li, Prashant Waiba, Sishir Gautam, Augusto Martins, Ricardo A. Rodrigues,Peter Kikstra, Marcel van der Horst, Emiliano R. Martins, Thomas F. Krauss, and Ashim Dhakal

Presented in CLEO 2022 San Jose (AM5M.8)

We report the detection of tryptophan at sub-ppb levels for a fluorometer based on Fresnel lenses and low-cost electronics. These fluorometers can be used to detect fecal contamination in drinking water, indicated by tryptophan-like fluorescence.

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Tryptophan-like fluorescence (TLF) for real-time detection in drinking and environmental water samples in Nepal

Anusa Thapa, Suvechhya Bastola, Shishir Gautam, Sanket Bohara, Prashant Waiba, Prajwal Rajbhandari, Thomas Krauss, Ashim Dhakal

International Conference on Bioscience and Biotechnology, Suraha, Nepal

A real-time, portable and low-cost detection method for the detection of fecal contamination in drinking water has been in demand, especially in developing countries. Studies [1,2] have demonstrated correlation between the intensity of Tryptophan-like…

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Non-diffracting beam generated from a photonic integrated circuit based axicon-like lens.

Maharjan, Rijan, Sanket Bohora, Pravin Bhattarai, Iain Crowe, Richard J. Curry, Richard Hogg, David Childs, and Ashim Dhakal.

Optics Express 29, no. 7 (2021): 10480-10490.

We demonstrate an on-chip silicon-on-insulator (SOI) device to generate a non-diffracting beam of ≈850 µm length from a diffractive axicon-like lens etched using a low resolution (200 nm feature size, 250 nm gap) deep-ultraviolet lithographic fabrication. The…

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CORNERSTONE’s silicon photonics rapid prototyping platforms: Current status and future outlook.

Littlejohns, Callum G., David J. Rowe, Han Du, Ke Li, Weiwei Zhang, Wei Cao, Thalia Dominguez Bucio et al

Current status and future outlook." Applied Sciences 10, no. 22 (2020): 8201.

The field of silicon photonics has experienced widespread adoption in the datacoms industry over the past decade, with a plethora of other applications emerging more recently such as light detection and ranging (LIDAR), sensing, quantum photonics,…

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Azimuthally apodized focusing gratings.

Maharjan, Rijan, Sanket Bohora, Richard Hogg, David Childs, Richard Curry, Iain Crowe, and Ashim Dhakal.

In 2020 Conference on Lasers and Electro-Optics (CLEO), pp. 1-2. IEEE, 2020.

We experimentally show that azimuthally apodized circular gratings can allow light to penetrate further into the structure, and create a focus of ≈ 10 μm, allowing for biomedical applications such as OCT.

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MMI-based compact spectrometer.

Bhattarai, Pravin, Sanket Bohora, Rijan Maharjan, Iain Crowe, and Ashim Dhakal

In Frontiers in Optics, pp. FTu2E-2. Optical Society of America, 2020.

We introduce a compact spectrometer based on a 1×16-multimode interference splitter partially filled with random holes. The spectral resolution for this high-bandwidth, on-chip device is found to be at least ~0.04 nm.

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Power and spectral characterization of a SOI chip-based axicon-like lens with 850um-long, 5.7 um-diameter central lobe.

Rijan Maharjan, Sanket Bohora, Pravin Bhattarai, Iain Crowe, Richard J. Curry, Richard Hogg, David Childs, and Ashim Dhakal

In Emerging Applications in Silicon Photonics, vol. 11577, p. 115770A. International Society for Optics and Photonics, 2020.

Distinguishing chemically similar particles in a complex environment has been a challenging problem in spectroscopy, such as micro-Raman spectroscopy. Here, we show that it is possible to distinguish particles from their spectroscopic signals in a modulated…

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Silicon nitride background in nanophotonic waveguide enhanced Raman spectroscopy

Dhakal Ashim, Pieter Wuytens, Ali Raza, Nicolas Le Thomas, and Roel Baets

Materials 10, no. 2 (2017): 140.

Recent studies have shown that evanescent Raman spectroscopy using a silicon nitride (SiN) nanophotonic waveguide platform has higher signal enhancement when compared to free-space systems. However, signal-to-noise ratio from the waveguide at a low analyte…

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