Gopalkrishna Hegde - Academia.edu (original) (raw)

Papers by Gopalkrishna Hegde

Journal of the Indian Institute of Sciences, Sep 7, 2022

In the century following its discovery, applications for quantum physics are opening a new world ... more In the century following its discovery, applications for quantum physics are opening a new world of technological possibilities. With the current decade witnessing quantum supremacy, quantum technologies are already starting to change the ways information is generated, transmitted, stored and processed. The next major milestone in quantum technology is already rapidly emerging-the quantum internet. Since light is the most logical candidate for quantum communication, quantum photonics is a critical enabling technology. This paper reviews the hardware aspects of the quantum internet, mainly from a photonics perspective. Though a plethora of quantum technologies and devices have emerged in recent years, we are more focused on devices or components that may enable the quantum internet. Our approach is primarily qualitative, providing a broad overview of the necessary technologies for a large-scale quantum internet.

International Journal of Visual and Performing Arts

Many of the Indian performing arts have deep scientific/engineering aspects involved in them with... more Many of the Indian performing arts have deep scientific/engineering aspects involved in them without being recognised or studied. Yakshagana is one of such arts being performed in coastal districts of Karnataka and has a history of more than 500 years. Yakshagana is a team, multidisciplinary art involving classical music, percussions, dance, dialogue, comedy, costumes, and scholarly discussions. This article discusses the components/parameters of the Yakshagana art form from a scientific and engineering perspective, and we have attempted to formulate mathematical equations for a better understanding of the art execution, artist’s capacity and overall performance. Empirical mathematical relations are formulated to estimate the performance index to grade the quality of the overall performance of the day. As art is an “all-in-one” form of art performance, it is represented using a Venn diagram. Four main components of Yakshagana and the importance of the coordination between them for s...

Measurement Science and Technology, 2015

ABSTRACT

Photonics

Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwi... more Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwidth optical communication links. Traveling wave electrodes are used to obtain high-speed modulation in these EOMs. We present the electrode design and analysis along with the study of effects of changing orientation on device performance for a thin-film lithium niobate tunable Mach–Zehnder interferometer (MZI) that offers sub-THz bandwidth operations. High velocity and impedance matching with low RF attenuation, high third-order SFDR (∼121 dB/Hz2/3) and a low half-wave voltage length product (1.74 V.cm) have been achieved for a bandwidth of 136 GHz. High-speed digital modulation using multi-level signal formats (PAM-2, QAM-4 and QAM-16) with low BER for 400 Gbps data has been demonstrated to assess the digital performance of the device.

2023 XXXVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)

Journal of Optics

In this work, an eight-channel dense wavelength division multiplexing demultiplexer is designed w... more In this work, an eight-channel dense wavelength division multiplexing demultiplexer is designed with a 2D photonic crystal triangular lattice. The proposed demultiplexer consists of a centre bus waveguide, an isosceles trapezium resonant cavity, and an eight-circular ring cavity (CR1, CR2, CR3, CR4, CR5, CR6, CR7, and CR8). The point defect resonant cavity consists of seven rods to drop different wavelengths from eight cavities, each of eight drop waveguides. The design is very simple to realise. The finite difference time domain and plane wave expansion method methods were used to analyse the proposed design’s band structure and transmission spectrum. The resonant wavelengths are 1.5441 μm, 1.5443 μm, 1.544 49 μm, 1.5447 μm, 1.5449 μm, 1.5451 μm, 1.5453 μm, and 1.5455 μm respectively. The proposed device provides a high-quality factor, transmission efficiency, and low crosstalk. The device’s footprint is 490.0 μm2, which can be easily incorporated into photonic integrated circuits.

Photonics

Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwi... more Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwidth optical communication links. Traveling wave electrodes are used to obtain high-speed modulation in these EOMs. We present the electrode design and analysis along with the study of effects of changing orientation on device performance for a thin-film lithium niobate tunable Mach–Zehnder interferometer (MZI) that offers sub-THz bandwidth operations. High velocity and impedance matching with low RF attenuation, high third-order SFDR (∼121 dB/Hz2/3) and a low half-wave voltage length product (1.74 V.cm) have been achieved for a bandwidth of 136 GHz. High-speed digital modulation using multi-level signal formats (PAM-2, QAM-4 and QAM-16) with low BER for 400 Gbps data has been demonstrated to assess the digital performance of the device.

arXiv (Cornell University), Dec 27, 2022

Cost-effective and programmable photonic-driven solutions like electronic counterparts (FPGAs) ca... more Cost-effective and programmable photonic-driven solutions like electronic counterparts (FPGAs) can be implemented using waveguide mesh architectures along with tunable couplers for routing to implement general-purpose photonic processors. These processors/ networks are represented using undirected weighted graphs, where weights are included to implement constraints in the routing. Faster automated routing and cycle finding algorithms are crucial for dynamic path allocations in live networks to implement various functionalities using these processors. We propose path and cycle finding algorithms based on bidirectional and depth-first search techniques, considering various performance metrics for each device to optimize the path according to the required metric. Multiple cases of path distribution and implementation of cycles of various sizes have been demonstrated. Various methods to eliminate the non-functioning or malfunctioning units are proposed. The broad applicability of the proposed path-finding algorithm has been demonstrated using the same algorithm to create a list of all the possible input-output combinations in a 4×4 photonic switching network. A comparison of available search algorithms in terms of execution time and complexity has been described.

Frontiers in Optics + Laser Science 2022 (FIO, LS)

A comparative analysis on the birefringence behavior in the newly emerging hybrid Si3N4 - LNOI an... more A comparative analysis on the birefringence behavior in the newly emerging hybrid Si3N4 - LNOI and proposed Si3N4 - TiO2 – LNOI platform is performed. The condition for zero and high birefringence has been established in the study for the X cut Y propagating LNOI configuration.

Optica Advanced Photonics Congress 2022

An alternate way of designing a grating coupler on X cut thin film LNOI-Si3N4 based platform is p... more An alternate way of designing a grating coupler on X cut thin film LNOI-Si3N4 based platform is proposed considering the contamination and fabrication issues in CMOS fabrication facility. The coupling efficiency of 44% at 1550nm and 3dB bandwidth of 45nm is obtained for X cut Y propagation Lithium Niobate.

Engergy systems in electrical engineering, 2022

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)

Organic photodetectors signify an emerging topic of organic electronics. These types of photodete... more Organic photodetectors signify an emerging topic of organic electronics. These types of photodetectors is a very researchable topic because of the interesting properties of different organic semiconductors. Polyethylene Terephthalate (PET) based organic photodetector (OPD) with bilayer heterojunction as active layer involving copper phthalocyanine (CuPc) and Phenyl-C60-butyric acid methyl-ester (PC60BM), has been fabricated for flexible light detection purposes. The spectral response was obtained for the OPD in the range from 300 to 800 nm. The highest EQE of 10.2% was observed at 475 nm.

ISSS Journal of Micro and Smart Systems

ISSS Journal of Micro and Smart Systems, 2022

Materials Science in Semiconductor Processing, 2021

Abstract We report the effect of europium doping on the structural, optical and nonlinear optical... more Abstract We report the effect of europium doping on the structural, optical and nonlinear optical properties of SnO2 thin films. The undoped and europium doped films (Eu: SnO2) at various concentrations (1 wt%, 3 wt% and 5 wt%) were synthesized via low-cost spray pyrolysis technique. X-ray diffraction (XRD) studies confirmed tetragonal rutile structure of both undoped and Eu: SnO2 thin films. An additional XRD peak at 31.6° was observed for 5 wt% Eu: SnO2 thin films due to the formation of Eu2O3 crystalline phase. The optical transmittance of Eu: SnO2 thin film has increased from 60% to 85% in visible region upon increasing europium concentration. The bandgap of Eu: SnO2 films was observed to be ~ 3.9 eV which further shows a nominal variation upon Eu doping. The PL spectroscopy studies shows emission peak along UV and red region corresponding to Near Band Edge (NBE) emission and oxygen vacancy defects incorporated in the films. The films exhibited good nonlinear optical properties upon europium doping indicating the applicability of grown films in future photonic devices.

ACS Applied Electronic Materials, 2022

Optical schemes based on light as an interrogating tool are in demand for quantitative flow visua... more Optical schemes based on light as an interrogating tool are in demand for quantitative flow visualization. The associated phase of the interrogating beam changes on passing through the flow field. The phase change of the light beam cannot be detected by a regular photodetector or by a camera as they can detect intensity only. In this manuscript, an experimental scheme is proposed for quantitative flow visualization. Intensity images captured at different defocused distances are used to recover the flow-induced-change in the phase of the interrogating light beam that later used to recover density distribution in the flow field by using tomographic inversion. The proposed technique is implemented in hypersonic shock tunnel facility, in which quantitative recovery of density around a hemispherically shaped model placed in hypersonic flow is investigated. Recovered density distributions around the model show good agreement with the numerical calculations carried out for the same.

Nanomaterials, 2021

In the present investigation, electron beam-influenced modifications on the CO gas sensing proper... more In the present investigation, electron beam-influenced modifications on the CO gas sensing properties of indium doped ZnO (IZO) thin films were reported. Dose rates of 5, 10, and 15 kGy were irradiated to the IZO nano films while maintaining the In doping concentration to be 15 wt%. The wurtzite structure of IZO films is observed from XRD studies post electron beam irradiation, confirming structural stability, even in the intense radiation environment. The surface morphological studies by SEM confirms the granular structure with distinct and sharp grain boundaries for 5 kGy and 10 kGy irradiated films whereas the IZO film irradiated at 15 kGy shows the deterioration of defined grains. The presence of defects viz oxygen vacancies, interstitials are recorded from room temperature photoluminescence (RTPL) studies. The CO gas sensing estimations were executed at an optimized operating temperature of 300 °C for 1 ppm, 2 ppm, 3 ppm, 4 ppm, and 5 ppm. The 10 kGy treated IZO film displayed ...

2018 4th IEEE International Conference on Emerging Electronics (ICEE), 2018

Hierarchical structures comprise of patterns which are themselves structured at lower length scal... more Hierarchical structures comprise of patterns which are themselves structured at lower length scales. Such structures can outperform the performance limits posed by continuum and non-hierarchical structures. However, the possible role of hierarchical structuring in photonics and optoelectronics are not well understood. Here we report on the implications of using materials structured at multiple length scales in the design of spectrally uniform photodetectors. We present our results on the design and fabrication of hierarchical structures comprising of alternating planar and nanostructured microscale domains interspersed with nanoscale objects. These structures show the possibility of obtaining unusual control over the flow of light compared to conventional non-hierarchical structures through the coupling of light across micro-domains. These multiscale structures are fabricated using self-assembly and a novel mechanical strain-augmented template based nano-molding process. We fabricat...

Journal of the Indian Institute of Sciences, Sep 7, 2022

In the century following its discovery, applications for quantum physics are opening a new world ... more In the century following its discovery, applications for quantum physics are opening a new world of technological possibilities. With the current decade witnessing quantum supremacy, quantum technologies are already starting to change the ways information is generated, transmitted, stored and processed. The next major milestone in quantum technology is already rapidly emerging-the quantum internet. Since light is the most logical candidate for quantum communication, quantum photonics is a critical enabling technology. This paper reviews the hardware aspects of the quantum internet, mainly from a photonics perspective. Though a plethora of quantum technologies and devices have emerged in recent years, we are more focused on devices or components that may enable the quantum internet. Our approach is primarily qualitative, providing a broad overview of the necessary technologies for a large-scale quantum internet.

International Journal of Visual and Performing Arts

Many of the Indian performing arts have deep scientific/engineering aspects involved in them with... more Many of the Indian performing arts have deep scientific/engineering aspects involved in them without being recognised or studied. Yakshagana is one of such arts being performed in coastal districts of Karnataka and has a history of more than 500 years. Yakshagana is a team, multidisciplinary art involving classical music, percussions, dance, dialogue, comedy, costumes, and scholarly discussions. This article discusses the components/parameters of the Yakshagana art form from a scientific and engineering perspective, and we have attempted to formulate mathematical equations for a better understanding of the art execution, artist’s capacity and overall performance. Empirical mathematical relations are formulated to estimate the performance index to grade the quality of the overall performance of the day. As art is an “all-in-one” form of art performance, it is represented using a Venn diagram. Four main components of Yakshagana and the importance of the coordination between them for s...

Measurement Science and Technology, 2015

ABSTRACT

Photonics

Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwi... more Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwidth optical communication links. Traveling wave electrodes are used to obtain high-speed modulation in these EOMs. We present the electrode design and analysis along with the study of effects of changing orientation on device performance for a thin-film lithium niobate tunable Mach–Zehnder interferometer (MZI) that offers sub-THz bandwidth operations. High velocity and impedance matching with low RF attenuation, high third-order SFDR (∼121 dB/Hz2/3) and a low half-wave voltage length product (1.74 V.cm) have been achieved for a bandwidth of 136 GHz. High-speed digital modulation using multi-level signal formats (PAM-2, QAM-4 and QAM-16) with low BER for 400 Gbps data has been demonstrated to assess the digital performance of the device.

2023 XXXVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)

Journal of Optics

In this work, an eight-channel dense wavelength division multiplexing demultiplexer is designed w... more In this work, an eight-channel dense wavelength division multiplexing demultiplexer is designed with a 2D photonic crystal triangular lattice. The proposed demultiplexer consists of a centre bus waveguide, an isosceles trapezium resonant cavity, and an eight-circular ring cavity (CR1, CR2, CR3, CR4, CR5, CR6, CR7, and CR8). The point defect resonant cavity consists of seven rods to drop different wavelengths from eight cavities, each of eight drop waveguides. The design is very simple to realise. The finite difference time domain and plane wave expansion method methods were used to analyse the proposed design’s band structure and transmission spectrum. The resonant wavelengths are 1.5441 μm, 1.5443 μm, 1.544 49 μm, 1.5447 μm, 1.5449 μm, 1.5451 μm, 1.5453 μm, and 1.5455 μm respectively. The proposed device provides a high-quality factor, transmission efficiency, and low crosstalk. The device’s footprint is 490.0 μm2, which can be easily incorporated into photonic integrated circuits.

Photonics

Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwi... more Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwidth optical communication links. Traveling wave electrodes are used to obtain high-speed modulation in these EOMs. We present the electrode design and analysis along with the study of effects of changing orientation on device performance for a thin-film lithium niobate tunable Mach–Zehnder interferometer (MZI) that offers sub-THz bandwidth operations. High velocity and impedance matching with low RF attenuation, high third-order SFDR (∼121 dB/Hz2/3) and a low half-wave voltage length product (1.74 V.cm) have been achieved for a bandwidth of 136 GHz. High-speed digital modulation using multi-level signal formats (PAM-2, QAM-4 and QAM-16) with low BER for 400 Gbps data has been demonstrated to assess the digital performance of the device.

arXiv (Cornell University), Dec 27, 2022

Cost-effective and programmable photonic-driven solutions like electronic counterparts (FPGAs) ca... more Cost-effective and programmable photonic-driven solutions like electronic counterparts (FPGAs) can be implemented using waveguide mesh architectures along with tunable couplers for routing to implement general-purpose photonic processors. These processors/ networks are represented using undirected weighted graphs, where weights are included to implement constraints in the routing. Faster automated routing and cycle finding algorithms are crucial for dynamic path allocations in live networks to implement various functionalities using these processors. We propose path and cycle finding algorithms based on bidirectional and depth-first search techniques, considering various performance metrics for each device to optimize the path according to the required metric. Multiple cases of path distribution and implementation of cycles of various sizes have been demonstrated. Various methods to eliminate the non-functioning or malfunctioning units are proposed. The broad applicability of the proposed path-finding algorithm has been demonstrated using the same algorithm to create a list of all the possible input-output combinations in a 4×4 photonic switching network. A comparison of available search algorithms in terms of execution time and complexity has been described.

Frontiers in Optics + Laser Science 2022 (FIO, LS)

A comparative analysis on the birefringence behavior in the newly emerging hybrid Si3N4 - LNOI an... more A comparative analysis on the birefringence behavior in the newly emerging hybrid Si3N4 - LNOI and proposed Si3N4 - TiO2 – LNOI platform is performed. The condition for zero and high birefringence has been established in the study for the X cut Y propagating LNOI configuration.

Optica Advanced Photonics Congress 2022

An alternate way of designing a grating coupler on X cut thin film LNOI-Si3N4 based platform is p... more An alternate way of designing a grating coupler on X cut thin film LNOI-Si3N4 based platform is proposed considering the contamination and fabrication issues in CMOS fabrication facility. The coupling efficiency of 44% at 1550nm and 3dB bandwidth of 45nm is obtained for X cut Y propagation Lithium Niobate.

Engergy systems in electrical engineering, 2022

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)

Organic photodetectors signify an emerging topic of organic electronics. These types of photodete... more Organic photodetectors signify an emerging topic of organic electronics. These types of photodetectors is a very researchable topic because of the interesting properties of different organic semiconductors. Polyethylene Terephthalate (PET) based organic photodetector (OPD) with bilayer heterojunction as active layer involving copper phthalocyanine (CuPc) and Phenyl-C60-butyric acid methyl-ester (PC60BM), has been fabricated for flexible light detection purposes. The spectral response was obtained for the OPD in the range from 300 to 800 nm. The highest EQE of 10.2% was observed at 475 nm.

ISSS Journal of Micro and Smart Systems

ISSS Journal of Micro and Smart Systems, 2022

Materials Science in Semiconductor Processing, 2021

Abstract We report the effect of europium doping on the structural, optical and nonlinear optical... more Abstract We report the effect of europium doping on the structural, optical and nonlinear optical properties of SnO2 thin films. The undoped and europium doped films (Eu: SnO2) at various concentrations (1 wt%, 3 wt% and 5 wt%) were synthesized via low-cost spray pyrolysis technique. X-ray diffraction (XRD) studies confirmed tetragonal rutile structure of both undoped and Eu: SnO2 thin films. An additional XRD peak at 31.6° was observed for 5 wt% Eu: SnO2 thin films due to the formation of Eu2O3 crystalline phase. The optical transmittance of Eu: SnO2 thin film has increased from 60% to 85% in visible region upon increasing europium concentration. The bandgap of Eu: SnO2 films was observed to be ~ 3.9 eV which further shows a nominal variation upon Eu doping. The PL spectroscopy studies shows emission peak along UV and red region corresponding to Near Band Edge (NBE) emission and oxygen vacancy defects incorporated in the films. The films exhibited good nonlinear optical properties upon europium doping indicating the applicability of grown films in future photonic devices.

ACS Applied Electronic Materials, 2022

Optical schemes based on light as an interrogating tool are in demand for quantitative flow visua... more Optical schemes based on light as an interrogating tool are in demand for quantitative flow visualization. The associated phase of the interrogating beam changes on passing through the flow field. The phase change of the light beam cannot be detected by a regular photodetector or by a camera as they can detect intensity only. In this manuscript, an experimental scheme is proposed for quantitative flow visualization. Intensity images captured at different defocused distances are used to recover the flow-induced-change in the phase of the interrogating light beam that later used to recover density distribution in the flow field by using tomographic inversion. The proposed technique is implemented in hypersonic shock tunnel facility, in which quantitative recovery of density around a hemispherically shaped model placed in hypersonic flow is investigated. Recovered density distributions around the model show good agreement with the numerical calculations carried out for the same.

Nanomaterials, 2021

In the present investigation, electron beam-influenced modifications on the CO gas sensing proper... more In the present investigation, electron beam-influenced modifications on the CO gas sensing properties of indium doped ZnO (IZO) thin films were reported. Dose rates of 5, 10, and 15 kGy were irradiated to the IZO nano films while maintaining the In doping concentration to be 15 wt%. The wurtzite structure of IZO films is observed from XRD studies post electron beam irradiation, confirming structural stability, even in the intense radiation environment. The surface morphological studies by SEM confirms the granular structure with distinct and sharp grain boundaries for 5 kGy and 10 kGy irradiated films whereas the IZO film irradiated at 15 kGy shows the deterioration of defined grains. The presence of defects viz oxygen vacancies, interstitials are recorded from room temperature photoluminescence (RTPL) studies. The CO gas sensing estimations were executed at an optimized operating temperature of 300 °C for 1 ppm, 2 ppm, 3 ppm, 4 ppm, and 5 ppm. The 10 kGy treated IZO film displayed ...

2018 4th IEEE International Conference on Emerging Electronics (ICEE), 2018

Hierarchical structures comprise of patterns which are themselves structured at lower length scal... more Hierarchical structures comprise of patterns which are themselves structured at lower length scales. Such structures can outperform the performance limits posed by continuum and non-hierarchical structures. However, the possible role of hierarchical structuring in photonics and optoelectronics are not well understood. Here we report on the implications of using materials structured at multiple length scales in the design of spectrally uniform photodetectors. We present our results on the design and fabrication of hierarchical structures comprising of alternating planar and nanostructured microscale domains interspersed with nanoscale objects. These structures show the possibility of obtaining unusual control over the flow of light compared to conventional non-hierarchical structures through the coupling of light across micro-domains. These multiscale structures are fabricated using self-assembly and a novel mechanical strain-augmented template based nano-molding process. We fabricat...