[SOLVED] RF over Fiber Optocs

[jay1691]

Hello All.

Can anyone suggest me for any reference design for RF over fiber optics.
I am familiar to Ethernet to Fiber converter and i have designed it, But This one is totally new for me.
Frequency range : 100kHz- 1GHz
Power Level : -80dbm

Thanks in advance.

 

[PlanarMetamaterials]

There's quite a bit of new literature in this field. Search for "microwave photonics".

 

[hagster]

I used these once to create a long delay line. It worked perfectly.

**broken link removed**

You can also roll your own with connectorised laser diode and photo diode receiver. If your not too worried about linearity then its pretty simple to do.

 

[jiripolivka]

I used these once to create a long delay line. It worked perfectly.

**broken link removed**

You can also roll your own with connectorised laser diode and photo diode receiver. If your not too worried about linearity then its pretty simple to do.

Please check KATHREIN of Germany, I think they have a solution for you.

 

[biff44]

- 80 dBm I pretty low. you wil need to RF amplify the signal BEFORE you use it to drive a laser diode, maybe up to the -10 0r 20 dBm level, in order to keep your signal to noise ratio good.

he RF signal is coupled to the laser diode thru a DC blocking capacitor. The laser diode has DC bias applied so that it is on partially, and the AC coupled RF modulates the intensity up and down. If you put too little RF signal on it, your amplitude modulation of the light is very little % wise.

 

[jay1691]

Hi biff44,

Thanks for your response. Can you please suggest any reference schematic or Block diagram that explain how this works ?
And yes after surfing i got that idea that i have to use RF amplifier.

As you said " RF signal is coupled to the laser diode thru a DC blocking capacitor " , But i thought that there is some type of module or PHY needed for this task.

 

[m11vajju]

Hi,

Also go through Emcore Radio over fiber designs.

 

[jay1691]

Hello All,
The hard part is that i have to design that not want to use ready made module

 

[biff44]

do you have a specific phase noise requirement? That will determine what type of laser diode you will need to buy. Laser diodes put out a white noise component (relative intensity noise) that can add to the phase noise of the signal, rendering certain types of modulation un-decypherable.

I HIGHLY suggest you buy a pigtailed laser module, with a fiber connector at the end of the pigtail---fiberoptic assembly is a whole new world.....

- - - Updated - - -

here is a high quality laser diode module that apparently is used in the cable tv industry:

**broken link removed**

DFB means it is distributed feedback type (a purer light spectrum), modified quantum well means it would have lower phase noise. Note that you have to choose a laser color, this one is 1550 nm