transistr laser ansh

8/8/2019 Transistr Laser Ansh

http://slidepdf.com/reader/full/transistr-laser-ansh 1/11

GYAN GANGAGYAN GANGA

INSTITUTE OF TECHNOLOGY ANDINSTITUTE OF TECHNOLOGY AND

MANAGEMENT MANAGEMENT



INTRODUCTIONINTRODUCTION

TRANSISTOR+ LASER= TRANSISTOR LASER

The transistor laser combines the functions of both a transistor and alaser by converting electrical input signals into two output signals,one electrical and one optical.



HOW TRANSISTOR LASERS AREHOW TRANSISTOR LASERS ARE

MADE?MADE?

-Bipolar Junction Transmitter (BJT), semiconductor device useselectrons and holes to carry the main electric current.

-Two back to back diode separated by a thin connection layer, abase layer.

-The quantum well is a layer of Indium-gallium-arsenide (10 nanometers thick). Inserted into the HBT (heterojunction bipolartransistor) base region.



WORKINGWORKINGWhen voltage is applied to the base-emitter junction, injected electrons from the emitter diffuse across the base.

The base is thin enough that most of the electrons can pass through to the

collector before recombining with holes in the p-type base.

Thesem

iconductor compound

s in thetransistor laser are Gallium-Arsenide

and Indium-Gallium-Phosphide.

These are direct band-gap

materials, an electron that has been

exci

tedi

nto the conducti

on band caneasily fall back to the valence band

through the creation of a photon (of

little momentum) whose energy

matches the band-gap energy.

So, these materials will readily produce light (photons)«.



Electrons that don·t recombine

with holes in the well exhibits a

current gain.

A voltage at the emitter

injects electrons in the well,

more electrons combine

with holes, a process which

emi

ts

li

ght.

The light is reflected off

mirrors around the inside of

the well to form a resonant

cavity and increasingly

s

ti

mulated unti

l a beam of laser light escapes.

The device can be switched on and

off rapidly (billions of switches per

second), and produces optical and

electrical signals.

Courtesy ieee.spectrum.org



- Quantum well acts as a recombination center governs the flow ofcharge from the emitter to the collector.

- This process decreases the current gain of the transistor by

approximately 90%.

-To turn this light into a laser beam, the edges of the transistor aremodified, creating a resonant cavity, stimulating the emission ofadditional photons that are in phase with the others generated in theregion.



DIODE LASER AND T RANSIST OR LASERDIODE LASER AND T RANSIST OR LASER

Injected carriers congregate in the quantum

well, where they recombine to emit radiation. At high drive frequencies, the optical response

of the diode laser, indicated in red, does not

follow the drive-current modulation, indicated

in blue (b).

In the reverse-biased collector

draws electrons out of the base region,

reducing the carrier lifetime.

The result is a much faster response which

enables transistor sources to operate at

higher data transmission rates (b).



APPLICATIONSAPPLICATIONS

-Optical interconnects replacesthewiring between components.

-As dual input, high frequencyprocessor.

-Offer signal mixing andswitching

capabilities.

-Offer potential for BroadbandCommunication.



FUT URE T RENDSFUT URE T RENDS

-Ultra-fast transistor lasers couldextend the modulation bandwidthfrom 20 GHz to 100 GHz.

-Faster internet connections andhigh definition video on cell phones.

-Used as optoelectronic interconnects ²transistor lasers facilitate faster signal processing,



CONCLUSIONSCONCLUSIONS

-Reduced carrier life time enables to operate at high data

transmission rate.

-Speed can be increased by improving optical signal intensity.



THANK YOU«.THANK YOU«.

ANY QUER

IE

S??ANY QUER

IE

S??

transistr laser ansh

Documents