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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
8/8/2019 Transistr Laser Ansh
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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.
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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.
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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)«.
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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
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- 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.
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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).
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APPLICATIONSAPPLICATIONS
-Optical interconnects replacesthewiring between components.
-As dual input, high frequencyprocessor.
-Offer signal mixing andswitching
capabilities.
-Offer potential for BroadbandCommunication.
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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,
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CONCLUSIONSCONCLUSIONS
-Reduced carrier life time enables to operate at high data
transmission rate.
-Speed can be increased by improving optical signal intensity.
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THANK YOU«.THANK YOU«.
ANY QUER
IE
S??ANY QUER
IE
S??