Today @ 4pm: Plasmonic LED for 10GHz direct modulation bandwidth: David Fattal / HP Labs

Dirk Englund englund at
Tue Jul 22 09:37:39 PDT 2008

Reminder - today's talk:

The OSA / SPIE Stanford Student Chapter presents:

Dr. David Fattal
HP Labs, Palo Alto

Title: Plasmonic LED for 10GHz direct modulation bandwidth: design and  

Tuesday, July 22, 2008
4:15pm, Ginzton building, AP 200
Refreshments at 4:00pm


Vertical Cavity Surface Emitting Lasers (VCSELs) are the de-facto  
choice for optical communication links less than 300~m long. They are  
reliable, efficient and are capable of modulation at speeds that  
exceed 10~Gb/s, but they are often the most costly element in the  
link. As the need for optical links moves from the campus to the  
server rack and to the board, the cost of the optoelectronics has been  
one of the key factors preventing widespread adoption at these shorter  
distance scales. Light Emitting Diodes (LED), with their simple  
epitaxial growth and device structure, provide a reliable, inexpensive  
alternative to laser-based systems in short-haul links.  The main  
drawback of LEDs is their limited modulation speed (<800~Mb/s for  
commercially available devices, 2~Gb/s for research devices).
In an LED, carriers recombine by spontaneous emission, a usually slow  
(> ns) process. One way to increase the LED speed is to heavily p-dope  
the semiconductor material, insuring a high hole concentration and  
electron-hole recombination rate. This technique has its limits since  
dopants also act as non-radiative recombination centers which  
eventually degrade the light production efficiency. Here we propose a  
low-cost solution to increase the device speed while maintaining high  
efficiency: a tensily strained quantum well interacting with Surface  
Plasmon Polaritons of moderate strength at 800 nm. We will take a  
pedagological approach in explaining how to simulate the structure  
numerically, and will present initial experimental results. An LED of  
this kind has the potential to accelerate the penetration of short- 
haul optical interconnections in a number of applications.

About our Speaker

David Fattal is a staff scientist in the Quantum Research Science  
group at HP Labs in Palo Alto, California. He received his  Ph.D. in  
Physics from Stanford university, where he worked on quantum  
information science in the group of Prof. Yoshihisa Yamamoto.  He  
holds a BS in mathematical physics from Ecole Polytechnique (France).

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