*SUMBER DAN DETEKTOR CAHAYA

How Does Optical Communication Work?

Sistem komunikasi optikLight source

Focus lens

Sensing element

Photo-detector

*DEVICE OPTOELEKTRONIK

*Light-Emitting Diodes (LEDs)LED = light emitting diode adalah sebuah dioda yang dapatmemancarkan cahaya jika mendapat bias maju. Karakteristik LED miripdengan dioda p-n. LED ini sibuat dengan berbagai macam panjanggelombang sehingga dapat dibedakan dari warnanya, umumnya adalahwarna merah (~ 650 nm), hijau (~550 nm) dan kuning (~600 nm).Disamping ada LED yang memancarkan cahaya infra merah (~950 nm)yang biasanya dipakai sebagai sumber cahaya pada sistem sensor,sedangkan LED cahaya tampak dipakai untuk indikator, peraga dalaminstrumen digital, dll..

LED - Light Emitting DiodesUV AlGaNBlue GaN, InGaNRed, green GaPRed, yellow GaAsPIR- GaAs

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LED - Colors & voltage drop

ColorWavelength (nm)Voltage (V)Semiconductor MaterialInfrared > 760V < 1.9Gallium arsenide (GaAs) Aluminium gallium arsenide (AlGaAs)Red610 < < 7601.63 < V < 2.03Aluminium gallium arsenide (AlGaAs) Gallium arsenide phosphide (GaAsP) Aluminium gallium indium phosphide (AlGaInP) Gallium(III) phosphide (GaP)Orange590 < < 6102.03 < V < 2.10Gallium arsenide phosphide (GaAsP) Aluminium gallium indium phosphide (AlGaInP)Gallium(III) phosphide (GaP)Yellow570 < < 5902.10 < V < 2.18Gallium arsenide phosphide (GaAsP) Aluminium gallium indium phosphide (AlGaInP) Gallium(III) phosphide (GaP)Green500 < < 5701.9 < V < 4.0Indium gallium nitride (InGaN) / Gallium(III) nitride (GaN) Gallium(III) phosphide (GaP)Aluminium gallium indium phosphide (AlGaInP) Aluminium gallium phosphide (AlGaP)Blue450 < < 5002.48 < V < 3.7Zinc selenide (ZnSe), Indium gallium nitride (InGaN), Silicon carbide (SiC) as substrate, Silicon (Si) Violet400 < < 4502.76 < V < 4.0Indium gallium nitride (InGaN)Purplemultiple types2.48 < V < 3.7Dual blue/red LEDs,blue with red phosphor,or white with purple plasticUltra-violet < 4003.1 < V < 4.4diamond (235nm), Boron nitride (215nm) , Aluminium nitride (AlN) (210nm) Aluminium gallium nitride (AlGaN) (AlGaInN) (to 210nm)WhiteBroad spectrumV = 3.5Blue/UV diode with yellow phosphor

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*Prinsip emisi cahaya dalam SemiconductorKetika elektron jatuh menuju hole ( jatuh ke energi yang lebih rendah) dilepaskan energi dalam bentuk photonPanjang gelombang cahaya tergantung pita energi bahan semikonduktor.

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*Bahan semikonduktor yang menghasilkan LED warna

General Brightness GaP GaN GaAs GaAIAs -- Green, Red Blue Red, Infrared Red, Infrared -- Super Brightness GaAIAs GaAsP GaN InGaN GaP Red Red, Yellow Blue Green Green Ultra Brightness GaAIAs InGaAIP GaN InGaN -- Red Red, Yellow, Orange Blue Green --

Panjang gelombang yang dipancarkan

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Direct and Indirect Materials

MaterialElement GroupBandgap EnergyEg (eV)Bandgap wavelengthlg (mm)TypeGeIV0.661.88ISiIV1.111.15IAlPIII-V 2.450.52IAlAsIII-V2.160.57IAlSbIII-V1.580.75IGaPIII-V2.260.55IGaAsIII-V1.420.87DGaSbIII-V0.731.70DInPIII-V1.350.92DInAsIII-V0.363.5DAnSbIII-V0.177.3D

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*Prinsip kerja LED

Sebuah LED harus dihubungkan resistor secara seri untuk membatasi arus LED. Nilai R diberikan :

Menghitung nilai resistorVS = TeganganVL = tegangan LED (biasanya 2V ed biru dan 4V awarna putih ) I = arus LED . 20mA),

ContohJika power suply VS = 9V, yang digunakan led merah ( 2 V)R = (9V - 2V) / 0.02A = 350 ohm .

R = (VS - VL) / I

*An LED must have a resistor connected in series to limit the current through the LED, otherwise it will burn out almost instantly. The resistor value, R is given by: R = (VS - VL) / I

LED di hubungkan seriExample Led merah , kuning dan hijau diperlukan tegangan 32V+2V=8V, Jika diberikan tegangan a9V dari battery. Maka arus yang melewati hambatan sebesar I=15 mA. Tentukan hambatan R yang harus dipasang.

Jawab :Hambatan R = (VS - VL) / I = (9 - 6) / 0.015 = 3 / 0.015 = 200,

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*Sambungan dengan fiber optic

Sambungan sumber cahaya dengan fiber optik

*Laser Diode

An Introduction to Fiber Optic Systems-John Powers

pn-junction laser LightAmplification byStimulated Emission ofRadiation

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Emitting Laser DiodeMonokromatik

*Laser Diodes (LDs)Lasers (Light Amplification by Stimulated Emission)

*Photo Diodes (PDs)A photodiode adalah semikonduktor yang berfungsi mengubah cahaya menhnjadi sinyal

*Operation Principle of a PD

*PDs Detection Range and Materials

MaterialWavelength range (nm)Silicon (Si)1901100Germanium (Ge)4001700Indium gallium arsenide (InGaAs)

Lead sulfide (PbS) 8002600

PenyambunganSchematic of a typical assembly of coupling opticsTransmitters employing a) butt-coupling and b) lens-coupling designs

Example Commercial Transmitter ModulePalomar Technologies

*Solar Energy SpectrumSpectrum of the solar energySolar radiation outside the earths surface:1.35 kW/m2, 6500 times larger than worlds energy demandAM0: radiation above the earths atmosphereAM1.5: radiation at the earths surface Blackbody radiation: ideal radiation

*Vision of Solar Cells (Photovoltaics)

*Operation Principle of Solar Cells

*Trends in optoelectronic devices Long wavelength, high power light sources or

photodetectors Nanoscale devices Low cost, easy fabricated materials High opto-electronic conversion efficiency Multi-wavelength sources

Next, my current research topic nanoscale optoelectronic devices

*Quantum Cascade Lasers (QCLs) a New Light Generation MechanismCascading effectAdvantages: Wavelength depends on layer thickness (flexible design) Well-mastered materials can be used for long wavelength Multiple colors can be generated in same laser High output power due to cascading effect

*Applications of QCL

*Then next I will talk little bit about the applications of QCL. Here I listed some applications. (blaBla)

*Quantum Dot Superlattice Solar CellAu grid bar

*Quantum Dot Superlattice Solar CellECVCurrent-voltage relationshipBand structure of quantum dot superlattices

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*An LED must have a resistor connected in series to limit the current through the LED, otherwise it will burn out almost instantly. The resistor value, R is given by: R = (VS - VL) / I*

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*Then next I will talk little bit about the applications of QCL. Here I listed some applications. (blaBla)