Fiber-Optic Communications

Slides:



Advertisements
Similar presentations
Chapter 9. PN-junction diodes: Applications
Advertisements

Chem. 133 – 2/12 Lecture. Announcements Lab Work –Supposed to Cover Set 2 Labs – but I probably won’t cover all and then will give an extra day for period.
Solomon Assefa, Nature, March 2010 Reinventing germanium avalanche photodetector for nanophotonic on- chip optical interconnects Jeong-Min Lee
Semiconductor Optical Sources
Optoelectronic Devices (brief introduction)
1 SEMICONDUCTORS Tunnel an Varactor Diodes. 2 SEMICONDUCTORS PN diodes and zener diodes have lightly doped PN junctions and similar V-I characteristics.
Optical Receivers Abdul Rehman. Receiver Components Most lightwave systems employ the digital format. Figure below shows a digital optical receiver Its.
EE 230: Optical Fiber Communication Lecture 11 From the movie Warriors of the Net Detectors.
Photodetector.
1 Chapter 5 Sensors and Detectors A detector is typically the first stage of a communication system. Noise in this stage may have significant effects on.
Lecture 31 Electrical Instrumentation. Lecture 32 Electrical Instrumentation Electrical instrumentation is the process of acquiring data about one or.
Lecture161 Instrumentation Prof. Phillips March 14, 2003.
Fiber-Optic Communications James N. Downing. Chapter 5 Optical Sources and Transmitters.
1 Detectors RIT Course Number Lecture Single Element Detectors.
Fiber-Optic Communications
Lecture 4b Fiber Optics Communication Link 1. Introduction 2
Photo Detectors Parameters: Parameters: Responsivity (Efficiency): Output current/input optical powerResponsivity (Efficiency): Output current/input optical.
Fiber Optic Receiver A fiber optic receiver is an electro-optic device that accepts optical signals from an optical fiber and converts them into electrical.
OPTICAL DETECTORS IN FIBER OPTIC RECEIVERS.
Optical Receiver Lecture 6.
Recall-Lecture 5 DC Analysis Representation of diode into three models
Microwave Engineering/Active Microwave Devices 9-13 September Semiconductor Microwave Devices Major Applications Substrate Material Frequency Limitation.
CUÑADO, Jeaneth T. GEQUINTO, Leah Jane P. MANGARING, Meleria S.
Chapter 6 Photodetectors.
4/11/2006BAE Application of photodiodes A brief overview.
V. Semiconductor Photodetectors (PD)
Photon detection Visible or near-visible wavelengths
3/26/2003BAE of 10 Application of photodiodes A brief overview.
Chapter 5 Optical Detector.
Venugopala Rao Dept of CSE SSE, Mukka Electronic Circuits 10CS32.
References Hans Kuzmany : Solid State Spectroscopy (Springer) Chap 5 S.M. Sze: Physics of semiconductor devices (Wiley) Chap 13 PHOTODETECTORS Detection.
ECE 590 Microwave Transmission for Telecommunications Noise and Distortion in Microwave Systems March 18, 25, 2004.
Chapter 6 Photodetectors.
Optical Receivers Theory and Operation
Fiber Optic Communication Lec 13 By Engr.Muhammad Ashraf Bhutta.
Optical Receivers Theory and Operation
References Hans Kuzmany : Solid State Spectroscopy (Springer) Chap 5 S.M. Sze Physics of semiconductor devices (Wiley) Chap 13 PHOTODETECTORS.
Photo Detectors for Fiber Optic Communication
1 Microwave Semiconductor Devices Major Applications Substrate Material Frequency Limitation Device Transmitters AmplifiersSi, GaAs, InP< 300 GHzIMPATT.
Chapter 10: Noise In Microwave Circuits
1 Stephen SchultzFiber Optics Fall 2005 Semiconductor Optical Detectors.
Title Light Detectors. Characteristics  Sensitivity  Accuracy  Spectral Relative Response(R( ))  Absolute Sensitivity(S( ))  Signal-to-noise ratio.
EE 230: Optical Fiber Communication Lecture 12
Photodetectors What is photodetector (PD)? Photodetector properties
Optical Receivers Theory and Operation
Chapter 6 Noise. Noise is a term generally used to refer to any undesired disturbances that mask the received signal in a communication system. Thermal.
Schottky Barrier Diode One semiconductor region of the pn junction diode can be replaced by a non-ohmic rectifying metal contact.A Schottky.
CHAPTER 1 Part 2.1  Noise.
Venugopala Rao Dept of CSE SSE, Mukka Electronic Circuits 10CS32.
College Name : Shree Swami Atmanand Saraswati Institute Of Technology(SSASIT)(076) Year : 2 nd year(3 rd sem) EC-2015 Subject Name : Electronic Devices.
EXAMPLE 2 – PHOTODIODE A photodiode is a semiconductor device that converts light into current. The current is generated when photons are absorbed in the.
What is thermal noise? Thermal noise in the resistance of the signal source is the fundamental limit on achievable signal sensitivity is unavoidable, and.
Topic Report Photodetector and CCD
CUÑADO, Jeaneth T. GEQUINTO, Leah Jane P. MANGARING, Meleria S.
Application of photodiodes
Electronics & Communication Engineering
PN-junction diodes: Applications
Power Semiconductor Systems I
OPTICAL SOURCE : Light Emitting Diodes (LEDs)
Photo Detectors.
Optical Receivers Theory and Operation
Photodetectors.
PIN DIODE.
Diode Theory Chap - 3 Release 1-Sep-2010 Jetking Infotrain Ltd.
V. Semiconductor Photodetectors (PD)
Chapter 6 Noise.
Optical Receivers Theory and Operation
ECE699 – 004 Sensor Device Technology
Optical Receivers 1. Photo Detectors
Noise I Abigail Firme.
Presentation transcript:

Fiber-Optic Communications James N. Downing

Optical Detectors and Receivers Chapter 6 Optical Detectors and Receivers

6.1 The Photodetection Process Optical Absorption Condition in which light striking an electron will create enough energy to exceed the bandgap energy and the photon is absorbed Absorption coefficient: The length of time that the photon energy in a material takes to decay exponentially Penetration depth: Depth to which the photon energy falls in the material

6.1 The Photodetection Process Quantum Efficiency The efficiency with which the light energy is converted to electrical energy Typical efficiencies range from 50 to 90% Responsivity The efficiency with which the photodetector converts the light energy to electrical energy (the transfer function)

6.1 The Photodetection Process Response Time The amount of time that a photodiode takes to respond to an optical input (in other words, the amount of time needed for the input of the photodiode to produce an output) Cutoff Frequency The maximum frequency that a device can transfer

6.2 Receiver Photodiodes A photodiode is a photodetector that uses a pn junction to detect light. When light strikes the pn junction, current is caused to flow in reverse bias. Dark current: Current that flows in the absence of light

6.2 Receiver Photodiodes pin Photodiode The pn junction is separated by a slice of intrinsic material. Most absorption takes place in the intrinsic and depletion layers, Increased quantum efficiency (near 100%) is due to wider depletion layer. Increase in response time

6.2 Receiver Photodiodes Avalanche Photodiode Makes use of an extra intrinsic p junction to increase photodiode gain Impact ionization Collision of accelerated charge carriers with other carriers causing them to ionize Avalanche breakdown The tremendous reverse voltage causing huge amounts of current to flow

6.2 Receiver Photodiodes MSM Photodiode Metal-semiconductor-metal Based on Schottky diodes Extremely fast response time High responsivity Efficiencies near 90%

6.3 Noise Factors Thermal Noise Shot Noise Other names: Johnson or Nyquist noise Due to random motion of electrons and dissipation of heat within the device Shot Noise The noise due to the small amount of current produced from the random light to electrical energy conversion

6.3 Noise Factors Dark Current Noise The noise due to the small amount of current that flows in the absence of light Increases with temperature and applied voltage

6.3 Noise Factors Signal-to-Noise Ratio The ratio of the communications signal to the amount of noise present The noise should be much smaller than the signal. Noise equivalent power is the minimum detectable power level at which the signal equals the noise in a 1-Hz system.

6.4 Amplifiers High Impedance Amplifier Transimpedance Amplifier High input impedance minimized thermal noise generated by the feedback of the amplifier Not suitable for wide bandwidths Transimpedance Amplifier Optimizes the tradeoffs between speed and sensitivity Improved dynamic range

6.4 Amplifiers Main Amplifier A second amplifier that is added after the front end amplifier to maximize the gain and bandwidth Contains the automatic gain control (AGC) Uses a low-pass filter to shape the output pulse Reduces noise

6.5 Receivers The Receiver Components Receives the incoming optical signal Converts an optical signal to an electrical signal Amplifies the electrical signal Components Optical input signal, photodiode, low-noise preamp, main amp, data recovery stage, and electrical output

6.5 Receivers Signal Recovery This circuit makes sure that the correct information is received Decision Circuit Compares the incoming signal to a threshold level to determine ones and zeros Clock Recovery Circuit Measures the bit slot and generates the clock pulse for the decision circuit

6.5 Receivers Receiver Performance Dynamic Range Sensitivity BER The range of detectable signal levels with linear response Sensitivity Minimum input optical power that can be detected BER Average probability of incorrect bit identification

6.5 Receivers Receiver Packaging All components must be protected from environmental conditions Transmission of correct signal Elimination of loss

6.5 Receivers Transceiver Transmitter and receiver in one unit