Jan Panteltje
Guest
Sat Mar 06, 2010 6:36 pm
Avalanche Photodetector, IBM, germanium, 1.5V, 40Gbps:
http://domino.research.ibm.com/comm/research_projects.nsf/pages/photonics.apd.html
Kevin McMurtrie
Guest
Sun Mar 07, 2010 6:52 am
In article <hmu3r7$nij$1_at_news.albasani.net>,
Jan Panteltje <pNaonStpealmtje_at_yahoo.com> wrote:
Quote:
Very cool, but made comical by the PR pictures showing snow avalanches.
--
I won't see Google Groups replies because I must filter them as spam
Jan Panteltje
Guest
Sun Mar 07, 2010 12:32 pm
On a sunny day (Sat, 06 Mar 2010 21:52:19 -0800) it happened Kevin McMurtrie
<mcmurtrie_at_pixelmemory.us> wrote in
<4b933f13$0$22180$742ec2ed_at_news.sonic.net>:
Quote:
Yes the reality in this world is slowly being replaced by 'artist impresions' and 'simulations'.
Nobody notices, the next mars rovers will actually be just some simulation running on google's computers.
And NASA will still get 100 billion for that mission.
John Larkin
Guest
Sun Mar 07, 2010 7:11 pm
On Sat, 06 Mar 2010 21:52:19 -0800, Kevin McMurtrie
<mcmurtrie_at_pixelmemory.us> wrote:
Quote:
This sort of thing is standard in press-release science. The
application sounds silly to me.
John
JosephKK
Guest
Mon Mar 08, 2010 7:54 am
On Sat, 06 Mar 2010 17:36:31 GMT, Jan Panteltje <pNaonStpealmtje_at_yahoo.com> wrote:
Quote:
Strange, APDs are very sensitive but not usually fast. T(on) may be quick and strong
but t(off) usually seems to be slow and sometimes troubled. Maybe there is some quench
circuitry involved that they are not talking about. Or maybe i, yet again, do not quite
know what i am about, Dr. Hobbs?
Phil Hobbs
Guest
Mon Mar 08, 2010 10:22 pm
On 3/8/2010 1:54 AM, JosephKK wrote:
Quote:
On Sat, 06 Mar 2010 17:36:31 GMT, Jan Panteltje<pNaonStpealmtje_at_yahoo.com> wrote:
Avalanche Photodetector, IBM, germanium, 1.5V, 40Gbps:
http://domino.research.ibm.com/comm/research_projects.nsf/pages/photonics.apd.html
Strange, APDs are very sensitive but not usually fast. T(on) may be quick and strong
but t(off) usually seems to be slow and sometimes troubled. Maybe there is some quench
circuitry involved that they are not talking about. Or maybe i, yet again, do not quite
know what i am about, Dr. Hobbs?
APDs are quick if the multiplication ratio is low and the ratio of the
avalanche cross sections of electrons and holes is small.
If only electrons cause avalanche ionization (Si is close to this
condition), the APD can be fast and fairly quiet--the initial electron
and all the multiplied ones arrive at once, while the holes trickle in
in 1 transit time. No bad speed tradeoff until the multiplication ratio
is over 50.
If electrons and holes have equal probability of inducing avalanches,
then the avalanche bounces back and forth randomly and can last much
longer and be much noisier. InGaAs is like that, which is why InGaAs
APDs have to be run at gains below about 10.
The better modern APDs use heterostructures, so the multiplication
occurs in a different semiconductor than the photodetection.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
