I do the same project like you.
I searched a tons of webpages for the Fiber-ethernet converter ideas. The answer is: YES, you can, BUT (always a "but" there) beware.
Not only Visette, other company offer you a way to design the converter module, here is some link: Avago products:
www.avagotech.com/docs/AV02-2989EN
Idea here is : You get a Transceiver that give you an output for Ethernet standard, use an PHY chip to execute the information and transfer it to RJ-45 port. transceiver here is : AFBR-5972Z. PHY chip is : IP113A-LF Good: you can make for your demo Bad : it only transmit in the range from 50m to maximum 70m
same with Texas Instrument, T.I also support the schematic design for converter board with TI PHY chip and fiber Transceiver from Avago. But, this board can support you to transmit over 2km
Some company have the final board for you to combine with your system such as: MPL company with board TX2FX
www.mpl.ch/DOCs/MPLdoc_00000370.pdf
Vitesse can help you too, it easier than above cause it connected directly with SFP cage.
BUT, the problem is: Transceiver module is very expensive compare to the final products from other company. Actually, the module cost you about 20 - 45$, and the PHY chip cost you about 5 - 10$. At, final board, you will cost about 60 - 75$. In fact, some fiber-ethernet converter box can be bought with only 16$ (included shipping cost)
But, wait a second. There is a hope for you. Some guys use Avago HFBR-14xxZ and HFBR-24xxZ to be a fiber transceiver to embedded into board with PHY chip. (i'm sorry cant post ), it cheaper than above, but at my point of view, it's still expensive.
www.avagotech.com/docs/AV02-0176EN
If you must defense your project, you should take your point of view about the process to make the board, cost, and the flexibility.
Wish you have a good luck.