3. OVERVIEW
In this presentation, we present some modern-day
technical applications of quantum well
technology. The small wavelengths made possible
by the well dimensions, which are generally in the
scale of nanometers, are useful in optics for diode
lasers, in measuring devices for IR photo detectors,
and much more which we will discuss in this
presentation. Many of these devices group or layer
quantum wells to improve output or performance.
4. LASER DIODE
A Quantum Well Laser is a laser diode in which the
active region of the device is so narrow that quantum
confinement occurs. Laser diodes are formed
in compound semiconductor materials that (quite
unlike silicon) can emit light efficiently. The wavelength
of the light emitted by a quantum well laser is
determined by the width of the active region rather than
just the bandgap of the materials from which it is
constructed. This means that much shorter
wavelengths can be obtained from quantum well lasers
than from conventional laser diodes using a particular
semiconductor material. The efficiency of a quantum
well laser is also greater than a conventional laser
diode due to the stepwise form of its density of
states function.
8. There are also several popular types of laser diodes available.
These include double heterostructure laser diodes that pack a layer
of low band-gap material between two layers of high band-gap
material. Typical materials include gallium arsenide (GaAs) and
aluminium gallium arsenide (Al-Ga-As). Other laser types include
single- and multiple-quantum well, separate confinement
heterostructure, and distributed feedback laser diodes. Typical
figures for wavelength variations with respect to applied voltage are
approximately 0.1 to 0.5 nm/°C, depending upon the type of
component and its frequency.
9. The advantages of laser diode are:
• The laser diode operates in lower power as compared to other laser.
• It has high coupling efficiency.
• It has better modulation capabilities.
• It can be used at high temperatures.
• The production of light can be precisely controlled.
• It can transmit optical output powers between the range of about 5 to
10 mW.
• It has low spectral width.
• It is compact and can easily be manufactured in arrays.
ADVANTAGES OF
LASER DIODE
10. DISADVANTAGES OF LASER
DIODE
Here are some disadvantages of laser diodes:-
• They are expensive as compared to LEDs which are less expensive and works
like laser diodes.
• They are not suitable for high-power application whereas LEDs are available for
all power applications.
• Its high-intensity beam is harmful to the eyes which can cause severe damage in
retina if they are directly looked.
• They require driver circuits to drive large lasers.
• Temperature affects its operation negatively and it greatly depends on it.
• It requires a cooling system to maintain temperature.
11. 11
USES OF LASER
DIODE
Quantum wells are used widely in :-
• Diode lasers, including red lasers for DVDs.
• Laser pointers
• Infra-red lasers in fiber optic transmitters, or in blue lasers.
They are also used to make HEMTs (high electron mobility
transistors), which are used in low-noise electronics.
12. Quantum well systems can be used to create compact, fast
computer chips, highly efficient microscopic lasers, and
optoelectronic devices; they form the basis of lasers in CD
players and microwave receivers. Blue light semiconductor
lasers use quantum wells.