Date post: | 05-Dec-2014 |
Category: |
Education |
Upload: | rajan-kumar |
View: | 6,340 times |
Download: | 6 times |
OPTICAL FIBER OPTICAL FIBER DETECTORDETECTOR
NAME:- SANDEEP KUMARNAME:- SANDEEP KUMAR
CLASS:- B.TECH 4 th YEARCLASS:- B.TECH 4 th YEAR
BRANCH:- ECEBRANCH:- ECE
CONTENTSCONTENTS
PHASE AND POLARIZATION PHASE AND POLARIZATION FIBER SENSORSFIBER SENSORS
INTRINSIC FIBER SENSORSINTRINSIC FIBER SENSORS
EXTRINSIC FIBER SENSORSEXTRINSIC FIBER SENSORS
INTRODUCTIONINTRODUCTION IT IS PART OF OPTICAL FIBER IT IS PART OF OPTICAL FIBER
RECEIVERRECEIVERIT CONVERTS IT CONVERTS OPTICALOPTICAL SIGNAL SIGNAL
INTO INTO ELECTRICALELECTRICAL SIGNAL SIGNAL THE ELCTRON EXCITED FROM THE ELCTRON EXCITED FROM
VALANCE VALANCE BAND TO BAND TO CONDUCTIONCONDUCTION BAND BAND
REQUIRED LOW REQUIRED LOW BIAS VOLTAGEBIAS VOLTAGE
PROCESS OF OPTICAL PROCESS OF OPTICAL FIBER DETECTORFIBER DETECTOR
ABSORPTION: ABSORPTION: TRANSPORTAION OF TRANSPORTAION OF CARRIER: CARRIER:
GENERATION OF GENERATION OF PHOTOCURRENT:PHOTOCURRENT:
PARAMETERS OF OPTICAL PARAMETERS OF OPTICAL FIBER DETECTORFIBER DETECTOR
ResponsivityResponsivity: :
Quantum EfficiencyQuantum Efficiency::CapacitanceCapacitance: : Response TimeResponse Time::Long wavelength Long wavelength
cutoffcutoff:: Wavelength = hc/EgWavelength = hc/Eg
noise equivalent noise equivalent power (NEP)power (NEP) : :
detectivitydetectivity : :
Figure 1— C-V Curve
PRINCIPLE OF OPERATIONPRINCIPLE OF OPERATIONWhen a photon strikes the diode, it excites an electron, creating a mobile electron and a positively charged hole.
If absorption occurs indepletion region,or diffusion length ,carriers are swept from the junction by built-in field .photocurrent is accured
TYPES OF OPTICAL FIBER TYPES OF OPTICAL FIBER DETECTORDETECTOR
THE OPTICAL FIBER THE OPTICAL FIBER DETECTOR IS BASICALLY DETECTOR IS BASICALLY THREE TYPETHREE TYPE:-:-
(1)(1)P-N PHOTODIODEP-N PHOTODIODE
(2)(2)P-I-N PHOTODIODEP-I-N PHOTODIODE
(3)(3)AVALANCHE PHOTODIODEAVALANCHE PHOTODIODE
(1)(1) P-N PHOTODIODEP-N PHOTODIODEIF INCIDENT IF INCIDENT
PHOTONS HAVE PHOTONS HAVE EEp =p =hfhf=≥ =≥ EEgg
THEN THEN ELECTRONSELECTRONS
MOVE FROM MOVE FROM VALACE BAND VALACE BAND TOTO
CONDUCTION CONDUCTION BANDBAND
(2)(2) P-I-N PHOTODIODEP-I-N PHOTODIODE
it consists of a thick, it consists of a thick, lightly doped lightly doped intrinsic intrinsic layerlayer sandwiched between sandwiched between thin p and n regionsthin p and n regions..
The word intrinsic means The word intrinsic means “natural”, “un-doped”. “natural”, “un-doped”. positive-intrinsic-negativepositive-intrinsic-negative..
PIN Photodiode
THE PIN PHOTODIODE IS THE PIN PHOTODIODE IS TWO TYPESTWO TYPES
(1)(1) FRONT ILLUMINATION PD FRONT ILLUMINATION PD :-:-
The light passes through the thin The light passes through the thin pp regionregion and generates electron-hole and generates electron-hole pairs in the thick pairs in the thick intrinsic layerintrinsic layer. .
(2)(2) REAR-ILLUMINATION PDREAR-ILLUMINATION PD:-:-
light enters the active region light enters the active region through a heavily doped through a heavily doped nn++ layer.layer. This layer is transparent This layer is transparent to the incident light because its to the incident light because its energyenergy gap is largergap is larger than the than the energy of incident photons.energy of incident photons.
(3)AVALANCHE (3)AVALANCHE PHOTODIODEPHOTODIODE
The free The free carriers createdcarriers created by by absorbed photonabsorbed photon. .
A A collisioncollision of carriers with of carriers with
neutral atoms ,bound electronsneutral atoms ,bound electrons
break out of the valence shell. break out of the valence shell. The The secondary carriersecondary carrier accelerate accelerate and create new and create new carriers. carriers. Require high-voltageRequire high-voltage
AVALANCHE PHOTODIODE AVALANCHE PHOTODIODE PROCESSSPROCESSS
Figure 4 — APD
PARAMETERS OF PARAMETERS OF AVALANCH AVALANCH
PHOTODIODEPHOTODIODEIMPACT IONISATION IMPACT IONISATION
COEFFICIENTCOEFFICIENTRESPONSE TIMERESPONSE TIMETHRESHOLD IONISATION ENERGYTHRESHOLD IONISATION ENERGYMULTIPLICATION FACTOR OR MULTIPLICATION FACTOR OR
CURRENT GAINCURRENT GAINRESPONSIVITYRESPONSIVITY
TYPES OF SENSORSTYPES OF SENSORSPHASE AND PHASE AND POLARIZATION FIBER POLARIZATION FIBER SENSORSSENSORS
INTRINSIC SENSORINTRINSIC SENSOR (1)OPTICAL MICROBENDING(1)OPTICAL MICROBENDING
SENSOR SENSOR
(2)OPTICAL FLOW METER(2)OPTICAL FLOW METER
SENSORSENSOR
EXTRINSIC SENSOREXTRINSIC SENSOR(1)OPTICAL FIBER LEVEL (1)OPTICAL FIBER LEVEL
DETECTORDETECTOR
(2)PHOTOELASTIC PRESSURE (2)PHOTOELASTIC PRESSURE
DETECTORDETECTOR
(3)FLUOROPTIC TEMPERATURE(3)FLUOROPTIC TEMPERATURE
DETECTORDETECTOR
(4)OPTICAL FIBER LASER (4)OPTICAL FIBER LASER DOPPLER VELOCIMETERDOPPLER VELOCIMETER
PHASE FIBER SENSORPHASE FIBER SENSOR
POLARIZATION FIBER POLARIZATION FIBER SENSORSENSOR
FIBER MICROBENDING FIBER MICROBENDING INTIRINSIC SENSORINTIRINSIC SENSOR
INTRINSIC OPTICAL INTRINSIC OPTICAL FIBER FLOW METERFIBER FLOW METER
EXTRINSIC FIBER EXTRINSIC FIBER OPTICAL FLUID LEVEL OPTICAL FLUID LEVEL
DETECTORDETECTOR
PHOTO ELASTICPHOTO ELASTIC PRESSUREPRESSURE SENSORSENSOR
FLUOROOPTIC FLUOROOPTIC TEMPERATURE SENSORTEMPERATURE SENSOR
FIBER LASER DOPPLER FIBER LASER DOPPLER VELOCIMETER VELOCIMETER