Background
The VCSEL (Vertical-Cavity Surface-Emitting Laser [v'?xl]) is a type
of semiconductor laser with laser beam emission perpendicular to the
chip surface, contrary to conventional edge-emitting semiconductor lasers
(also in-plane lasers) where laser light is emitted at one or two edges.
VCSELs are the product of sophisticated process technology, especially
the epitaxial growth, to achieve the laser cavity properties.
The first prototype VCSEL was presented in 1979 by Soda, Iga, Kitahara
and Suematsu, but devices with a threshold current below 1 mA have been
reported since 1989. Today, VCSELs have replaced edge-emitting lasers
in applications for short-range fiberoptical communiation such as Gigabit
Ethernet and Fibre Channel.
The first commercial VCSEL was sold in 1996 and a total of 1 million
VCSELs were sold by 1998. During the telecom boom which ended in 2001,
a total of 20 million VCSELs were sold. As of the 1st Quarter 2005, it
is estimated that a total of 50m VCSELs have been shipped and that Advanced
Optical Components has shipped 35m of that total. With the down turn
of telecoms in 2001, Advanced Optical Components came into being when
Honeywell sold its VCSEL division. It is now a subsidiary of Finisar
and is actively seeking new applications for VCSELs including their use
as sensors.
The decline in the sales rate was directly attributable to the primary
VCSEL application in fiber optics telecommunications. Now the industry
is actively engaged in increasing the number of applications, including
tracking. A variety of products have been shipped with wave lengths ranging
from 665nm to 1550nm. The target is 1550nm for fiber optics communication
which most closely matches the performance of the fiber.
Most of the VCSEL research effort has been devoted
to improving the communications bandwidth and matching the wavelength
of emission
to the best pass band of optical fiber. There is one problem – this
only applies to upgrading the bandwidth of all the dark fiber which
is in
the ground. It can be said that Passive Optical Networking (PON)
would be another telecom growth market that has yet to materialize
in high
volumes.
VCSELs have not appeared in consumer electronics
in that there has been no demand for its attributes. At the WAVE,
we find it telling
that Sony
is only developing VCSELs for the communications sector. Yes, there
may be other applications but most of the high volume ones cited for
its
existing product line are the obvious uses – DVD and even Blu-Ray.
New Computer Technology
The advantages of VCSELs are well known:
High efficiency
It can be battery powered
Optical emission is suited for many applications - well formed directional
beam with Gaussian like shape
High Reliability
Single and MultiMode Lasers are possible
The best known large-scale application for the tracking properties of
lasers is the computer mouse. It is the objective of VCSEL research to
develop a tracking sensor that is integral to a computer mouse and can:
Provide superior surface tracking, especially on clear glass surfaces
Optimize user experience given the high tracking speed and spatial accuracy
of laser
Of course, the mouse is not the only imaginable VCSEL application (outside
of the telecommunications industry). Certainly, any environment that
requires tracking information, such as manufacturing assembly lines,
security or stock management, might be another venue for development.
It could even be imagined that VCSELs could morph into the RFID arena.
Aglient Techonologies has made the strongest move
toward a VCSEL emitter for optical tracking. Since Agilent already
makes VCSEL emitters for
the telecommunications market, it has experience with the technology.
There is an Agilent “game mouse” already in production.
The optical tracking mouse is a sensor application for VCSELs which
drives
volumes well beyond telecoms, and it could well be 10 times the current
telecom sales of VCSELs.
However, there are two major issues to be resolved: price and market
response.
Laser products have higher market prices than LED tracking devices.
The price for a laser mouse shipped by a manufacturer is the same as
an LED finished mouse sold at retail. If the peripherals industry provides
the right message, this price differential may only last until 2006 or
2007. The acceptance of a superior tracking product to the purchasing
public will mandate a reduction in manufacturing costs, made possible
by volume sales.
The real question, however, is – does this look like and sound
like the mystical 4GHz PC CPU? That is, how many need it? In the WAVE’s
view, the holy grail of mouse tracking has not been achieved: it must
track as fast as laser with the surface tolerance of a ball. If this
can be accomplished, the technical and market message behind VCSEL
becomes much more compelling.
Links:
www.lasermate.com
www.puretechinc.com
searchsmb.techtarget.com
