Raghuram Narayan - Academia.edu (original) (raw)

Papers by Raghuram Narayan

Research paper thumbnail of Rewritable Multilevel Recording by Mark-Size Modulation on Growth-Dominant Phase-Change Material

Japanese Journal of Applied Physics, 2001

Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level ... more Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level write intensity modulation and duty ratio control of writing and cooling pulses on conventional four-layer stack, was realized using an eutectic growth-dominant phase-...

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Research paper thumbnail of Electrooptic coefficient variation in proton exchanged and annealed lithium niobate samples

IEEE Journal of Selected Topics in Quantum Electronics, 1997

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Research paper thumbnail of Rewritable Multilevel Recording by Mark-Size Modulation on Growth-Dominant PhaseChange Material

Japanese Journal of Applied Physics, 2001

Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level ... more Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level write intensity modulation and duty ratio control of writing and cooling pulses on conventional four-layer stack, was realized using an eutectic growth-dominant phase-...

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Research paper thumbnail of Tunable Chirp Managed Laser

IEEE Photonics Technology Letters, 2008

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Research paper thumbnail of 100Gb/s 10km link performance of 10×10Gb/s hybrid approach with integrated WDM array of DFB lasers

We demonstrate a 100 Gb/s 10 km link using hybrid packaging containing a monolithic WDM array of ... more We demonstrate a 100 Gb/s 10 km link using hybrid packaging containing a monolithic WDM array of DFBs a PLC based optical MUX, an array of PDs and TIAs , and a PLC based optical DeMUX.

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Research paper thumbnail of Electro-optic coefficient mapping and the design, fabrication and analysis of coplanar waveguide resonators in lithium niobate

The main topics in this dissertation are (a) Investigation of Electro-Optic (EO) coefficient vari... more The main topics in this dissertation are (a) Investigation of Electro-Optic (EO) coefficient variation in lithium niobate and (b) the design, fabrication and analysis of coplanar waveguide resonant electrodes for EO modulators. An optical sampling technique is used to determine the EO coefficient variations in lithium niobate processed using the titanium in-diffusion technique and the Annealed Proton Exchange (APE) technique. A spatial mapping of the EO coefficients in lithium niobate is presented. The measurements enable us to quantitatively estimate the reduction in the EO coefficient as a function of the processing conditions. The results clearly indicate that samples processed using titanium in-diffusion show no degradation of the EO coefficient. Samples processed using the APE technique display a dramatic drop in the processed region immediately after the proton exchange step. Thermal annealing is shown to restore the EO coefficient in the proton exchanged regions. But the efficacy of thermal annealing is dependent on the initial proton exchange process. Prolonged thermal annealing is effective in restoring the EO coefficients provided the initial proton exchange depth is less than 1.5/mu m. Coplanar Waveguide (CPW) is a popular planar transmission line because of its tight confinement and non-dispersive nature at high frequencies (>60 GHz). In this dissertation, several CPW resonant electrodes have been fabricated, tested and analyzed. The advantage of CPW resonant electrode structure is that there is an enhancement in the field strength by a factor proportional to /sqrt[Q], where Q is the quality factor of the resonator. The dis-advantage is that the device is narrow-band in its frequency response. The focus of this dissertation is to investigate the design and fabrication issues related to CPW resonators. The results indicate the need for better design tools to properly predict the performance of the resonator and in general CPW structures. The measurements are compared with theory to describe the electro-magnetic behavior of the CPW resonator. A novel pseudo-TEM mode analysis has been adopted to determine the characteristics of the even mode of the coplanar waveguide.

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Research paper thumbnail of Rewritable Multilevel Recording by Mark-Size Modulation on Growth-Dominant Phase-Change Material

Japanese Journal of Applied Physics, 2001

Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level ... more Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level write intensity modulation and duty ratio control of writing and cooling pulses on conventional four-layer stack, was realized using an eutectic growth-dominant phase-...

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Research paper thumbnail of Electrooptic coefficient variation in proton exchanged and annealed lithium niobate samples

IEEE Journal of Selected Topics in Quantum Electronics, 1997

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Research paper thumbnail of Rewritable Multilevel Recording by Mark-Size Modulation on Growth-Dominant PhaseChange Material

Japanese Journal of Applied Physics, 2001

Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level ... more Abstract Rewritable multilevel recording based on reflectivity modulation, by means of two-level write intensity modulation and duty ratio control of writing and cooling pulses on conventional four-layer stack, was realized using an eutectic growth-dominant phase-...

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Research paper thumbnail of Tunable Chirp Managed Laser

IEEE Photonics Technology Letters, 2008

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Research paper thumbnail of 100Gb/s 10km link performance of 10×10Gb/s hybrid approach with integrated WDM array of DFB lasers

We demonstrate a 100 Gb/s 10 km link using hybrid packaging containing a monolithic WDM array of ... more We demonstrate a 100 Gb/s 10 km link using hybrid packaging containing a monolithic WDM array of DFBs a PLC based optical MUX, an array of PDs and TIAs , and a PLC based optical DeMUX.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electro-optic coefficient mapping and the design, fabrication and analysis of coplanar waveguide resonators in lithium niobate

The main topics in this dissertation are (a) Investigation of Electro-Optic (EO) coefficient vari... more The main topics in this dissertation are (a) Investigation of Electro-Optic (EO) coefficient variation in lithium niobate and (b) the design, fabrication and analysis of coplanar waveguide resonant electrodes for EO modulators. An optical sampling technique is used to determine the EO coefficient variations in lithium niobate processed using the titanium in-diffusion technique and the Annealed Proton Exchange (APE) technique. A spatial mapping of the EO coefficients in lithium niobate is presented. The measurements enable us to quantitatively estimate the reduction in the EO coefficient as a function of the processing conditions. The results clearly indicate that samples processed using titanium in-diffusion show no degradation of the EO coefficient. Samples processed using the APE technique display a dramatic drop in the processed region immediately after the proton exchange step. Thermal annealing is shown to restore the EO coefficient in the proton exchanged regions. But the efficacy of thermal annealing is dependent on the initial proton exchange process. Prolonged thermal annealing is effective in restoring the EO coefficients provided the initial proton exchange depth is less than 1.5/mu m. Coplanar Waveguide (CPW) is a popular planar transmission line because of its tight confinement and non-dispersive nature at high frequencies (>60 GHz). In this dissertation, several CPW resonant electrodes have been fabricated, tested and analyzed. The advantage of CPW resonant electrode structure is that there is an enhancement in the field strength by a factor proportional to /sqrt[Q], where Q is the quality factor of the resonator. The dis-advantage is that the device is narrow-band in its frequency response. The focus of this dissertation is to investigate the design and fabrication issues related to CPW resonators. The results indicate the need for better design tools to properly predict the performance of the resonator and in general CPW structures. The measurements are compared with theory to describe the electro-magnetic behavior of the CPW resonator. A novel pseudo-TEM mode analysis has been adopted to determine the characteristics of the even mode of the coplanar waveguide.

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