Optoelectronics-what is a laser and modulator driver?

[nearxos]

i am doing a research on optoelectronic components for communication.
Can anybody explained me what a laser and modulator driver is and how it work?

Regards

 

[nearxos]

types of laser diodes

can anybody help me.

i am trying to find what types of laser diodes there and how to categorize them.

i search through numerous website but the more i search the more i got confused.

regards

 

[berkeman]

Welcome to the PF, nearxos.

I merged your two similar threads. Here is some basic info on laser diodes:

http://en.wikipedia.org/wiki/Laser_diode

What can you tell us about how laser diodes are used in communications?

 

[Redbelly98]

i am trying to find what types of laser diodes there and how to categorize them.

Well, a few ways I can think of might be

• Wavelength, or wavelength range.
• Material of composition. This would go hand-in-hand with the wavelength range of the laser.
• Power level.
• Type of construction. For example: gain guided, index guided, VCSEL. Also, single-stripe vs. array.

 

[waht]

Also you might want to read about RF-to-Fiber links.

Here is a link to specs of an actual RF-to-fiber modulator used in telecom, and military:

http://www.naic.edu/~phil/mbeam/anacomDesign.pdf

 

[nearxos]

thank you all for your help. i have another question now.

i am writing the basic theory for LEDs. and in some article i read that that the effect that occurs to emit light is called "electroluminescence" but in some other articles is called "spontaneous emission" are these two terms the same thing. i did some search and i didnt find anything that relates this two.

 

[stevenb]

i am writing the basic theory for LEDs. and in some article i read that that the effect that occurs to emit light is called "electroluminescence" but in some other articles is called "spontaneous emission" are these two terms the same thing. i did some search and i didnt find anything that relates this two.

They are basically the same thing in this context. Spontaneous emission is a general term for when atoms "naturally" decay from a higher energy level to a lower energy level, with the emission of a photon. The word "naturally" means that it is just a random thing that happens on its own at a certain average rate and with a certain probability. There are many ways for the atom to become excited in the first place, including thermal, phonon, photon and electrical excitation. Electroluminescence is a more specific case where electricity causes the excitation of the atoms, which then decay with the emission of light. I'm not sure that this terminology requires that the optical emission be due to spontaneous emission (as opposed to stimilated emission), but in the case of a standard LED, most optical emission would be spontaneous.

 

[nearxos]

i write the following sentence. does it make any sense or its wring?

"The junction in a LED is forward biased and when electrons cross the junction from the n- to the p-type material, the electron-hole recombination process produces some photons in the IR or visible light this process is called spontaneous emission and produce the effect of electroluminescence. An exposed semiconductor surface can then emit light."