Ramesh K. Sonkar

Fabrication of F-ion implanted quantum well intermixed waveguide grating

This paper reports the ion implantation induced quantum well intermixing used to fabricate waveguide gratings for applications at CWDM wavelengths on InGaAsP/InP multi quantum well structure. The waveguide is fabricated using reactive ion etching (methane chemistry) with a surface roughness 2∼3nm. Focused ion beam is used to open windows for fluorine implantation on titanium mask followed by anneal under forming gas environment. The transmission spectrum of the waveguide has been measured and found cross talks of −10dB among the adjacent channels. The insertion loss of the fabricated waveguide gratings is less than 5dB.

CWDM integrated waveguide gratings by InGaAsP/InP quantum well intermixing

Integrated waveguide Bragg gratings have been designed and fabricated for CWDM wavelengths using F implantation and annealed quantum well intermixing technique, compatible with microelectronics processing. The measured peaks are blue shifted by ~35nm from that of the design and FWHM width widened by ~1nm due to inaccuracies in the processing. The measured insertion loss is ~4dB.

Non-invasive measurement of heart rate and hemoglobin concentration level through fingertip

This paper proposes a low cost method for the estimation of blood parameters using photo-plethysmography (PPG) technique. Data is obtained non-invasively from the fingertip, which is processed to estimate the heart rate and the hemoglobin concentration. The signal received from fingertip is first processed via analog filters and the output is sent to a computer through a microcontroller interface to be processed using MATLAB in order to estimate the parameters. The proposed method can be used for health monitoring purposes in rural areas. Furthermore, this solution could be ported to work on a standalone device, thus eliminating the need for a computer.

Design and proposal of dual line-of-defense perimeter watchdog incorporating optimally designed FBG based accelerometers and strain sensors using single optical fiber

Paper presents Opto-Mechanical intrusion sensor fence with FBGs attached to mechanical accelerometers and strain sensors, optimized on SolidWorks 2013 for desired frequency to 35 Hz, picking up accelerations/ strains and its deployment for perimeter security. The accelerometer structure consists of inertial mass supported by an L-shaped modified cantilever beam having non-uniform cross section area connected to base by a thin neck element which acts as strain concentrated centre hence an optimum zone for FBG sensors placement. Bragg wavelength shifts were obtained on Optigrating software for the obtained strain values on mechanical assembly of fence. CFD wind analysis is performed on the assembly to obtain the spot for accelerometer’s placement to avoid false alarms up to wind velocities of 20 m/s.

Determination of transformer oil age using long period grating

This paper presents about the determination of age of transformer oil using long period grating. The aging of the oil leads to change in refractive index of cladding, which shifts the Bragg wavelength of the long period gratings. The sensitivity is higher with the long period grating in comparison to the others.

Analysis of implantation induced gratings for CWDM

The Bragg reflection coefficients suitable for a CWDM system have been calculated by using coupled mode theory based on perturbation obtained by impurity induced intermixing of quantum wells and analyzed for different order gratings.