Somdatta MITRA

En résumé

Entreprises

• ST Microelectronics - Validation Engineer

  2007 - maintenant

• Alcatel-Thalés 3-5 Labs,Paris - Intern

  2006 - 2007 => Co-Author - Actively Mode-Locked Fabry-Perot Laser Diode Module for Sampling Applications - ECOC 2007 - 33rd European Conference and Exhibition on Optical Communication
  We report on a Fabry-Perot laser diode packaged in a module compatible with active mode-locking. We obtained narrow pulses (2ps) with an ultra-low level jitter (<200fs) at 17GHz, this is compatible with optical sampling applications. This area focuses on device (incl. planar-waveguide optical components, bulk-optical technologies and photonic band gap devices) and semiconductor components for processing of optical signals, optical signal generation, amplification, switching and detection. Technologies needed to develop commercial devices are also covered.
  
  =>RF power consumption problem of an actively mode locked, two section, QD Fabry-Perot laser diode.
  To drive an actively mode locked Laser diode, a RF source is required. Especially at a high transmission speed most of the RF power supplied by the RF source is reflected back and thus does not contribute to the driving of the actively mode locked Laser diode. My role in the project is to decrease this power consumption; by doing impedance matching and by designing more intelligently the device structure for efficient high speed transmission above 40GHz. This study includes both theoretical and experimental parameter extractions of a Laser diode followed by simulations in ADS. The electrical equivalent models of mono-section and two-section Lasers have been derived including the parasitic components and several methods for parameter extractions have been studied. This project required electronic circuit designing dealing with Analogue Electronics as well as RF designing and Optical Engineering.
  
  => Ultra-Narrow Mode-Beating Spectral Line-Width of a Passively Mode-Locked Quantum Dot Fabry-Perot Laser Diode.
  My role in this project is to work on the fabrication and characterization of QD-based passively mode-locked laser diode generating pulses at 17 GHz. We demonstrate that such a device enables us to achieve the narrowest line-width (2KHz) of the mode beating spectrum. The pulse profile is measured using an autocorrelation system based on second harmonic generation in a nonlinear crystal. The narrowest pulse width of the autocorrelation signal is around 4 ps corresponding to a pulse width of around 1.9 ps after de-convolution assuming a Lorentzian shape. It should be stressed here that such a narrow line-width has never been obtained with a laser diode and this fact confirms the reduction of electrical line-width in QD-material based laser diodes compared to bulk or quantum well laser structures. Such a narrow line-width would lead to a very small time-jitter for this kind of laser pulse source, when it is actively mode-locked. Such characteristics are a good omen for the implementation of ultra-stable pulse sources, which can be used either as clock signal in synchronous operations or as low noise sampling signal in analogue to digital conversion applications.
  
  => Electronics, Lasers, RF and Optical Communication, Semiconductor Physics, Telecommunication, ADS, COMSIS, Oscilloscopes, Spectrum and Network analyzers, Frequency Synthesizers, filters, amplifiers, Adaptive Tuners, Windows 9x, Unix, MS Office

• Sri Sai Enterprises - CDI

  2004 - 2005 Objective of the project
  The objective of this project was to study the effects of bit-rate and distance on S/N ratio in a WDM system and to predict ways to overcome these difficulties.
  
  Company description and activity
  Sri Sai Electronics is a part of Sri Sai Enterprises, which is a small manufacturing company in Pune, India. It is more like a consulting company, who undertakes projects from larger companies on contract and is responsible for the design and development from the basic studies to the transfer for industrialization. Its clientele includes companies in both civil and military sectors.
  
  Objective of the project
  a. Military applications e.g. missile guided system.
  b. Satellite communication application.
  c. Weather Study experiments e.g. Weather balloon.
  
  
  ENGINEERS PROJECT
  
  The aim of this project was to develop a fully automatic system for antenna tracking as well as for calculating various parameters of the antenna. A YAGI antenna had been used here. This antenna was mounted on a stepper motor by mechanical means. The antenna can be rotated either in real time mode or off-line mode. When the stepper motor rotates, the antenna also rotates and at each step angle, the TV signal caught by the antenna is stored in the P.C. for further analysis and calculation. The stepper motor is rotated with the help of a stepper motor driver card. This card rotates the motor and also controls the parameters like its speed, step size and direction under the basic control of the software. This stepper motor driver card is interfaced to the P.C. by RS232. The signals received by the antenna are given to a field strength meter, which detects the signal, amplifies it and converts it into DC signal. This is further amplified, digitized and then stored in the computer. The project has manifold applications like, laboratory purposes, military and radar applications etc.
  
  I have developed several modules of the software which would control all the working and calculations of this project in C language.
  
  I was also responsible for the testing of ICs as well as various circuits such as ADC card (ADC 0804), Stepper Motor Driver card (L 297, L 298, MAX 232), Pre-Amplifier Card (LM 324) and Data Acquisition Card.
  
  I have studied the working of Intel Microprocessor 8085 in detail and also I have tested several VHDL programs (already developed) manually.
  
  I have also Tested the various standards for quality maintenance of ‘Exide Batteries’. Various tests had been carried out to test the functionality of the batteries in various environments. Testing of the battery circuits, it’s layout, durability and functionality were strictly maintained according to the client demands and standard statistics. My role was also to interact with the clients and convey their demands to the development department.
  
  In short:
  a. Planning, implementing and executing the designs for an Automatic Yagi Antenna Tracking System in VHF band (30–300 MHz)
  b. Electronic circuit design, implementation and testing
  c. Stepper Motor and Motor Driver Circuit design and implementation
  d. Development and Testing of different modules in C language for controlling hardware, motor circuit and other operations
  e. Electrical and VHF signal processing
  f. Manual VHDL testing
  g. Interaction with customers to discuss defects found on the circuit and software testing

Formations

• Institut National Des Télécommunications (Evry)

  Evry 2005 - 2007 Master of Science - Electrical and Optical Engineering

• Pune University (Pune)

  Pune 2000 - 2004 Bachelor of Electronics and Telecommunication Engineering

Réseau

• Arthur AFONSO

• Hassan FADLI

• Mei LI

• Romain HAROUTUNIAN