Author Topic: bidirectional fibre tranceivers  (Read 429 times)

0 Members and 1 Guest are viewing this topic.

Offline Tangent_Tracker

  • Contributor
  • Posts: 26
bidirectional fibre tranceivers
« on: October 21, 2021, 10:47:24 am »
Hi folks, so we use small PCB mount ST fibre transmitters/recievers (Broadcom/Avago) at work for fibre connections of about 200m. We are a bit low on fibres at the moment and so I started looking for bidirectional devices. You can get these as complete units that will plug directly into network cards/switches etc, but what I would like is a unit that I can mount to a PCB (or with a standard connector) that simply has a UART port or even direct laser access as in the above modules.

Short of hacking one of these commercial offerings, does anyone know of any units available with a much-simplified interface, as I cannot find anything!
 

Offline PartialDischarge

  • Super Contributor
  • ***
  • Posts: 1334
  • Country: 00
Re: bidirectional fibre tranceivers
« Reply #1 on: October 21, 2021, 10:58:54 am »
I guess you mean bidirectional modules but not over the same fiber cable.
Is it 1mm plastic fiber you are using?
What speed ? Does it need to be full duplex or can it be half duplex?
 

Offline Tangent_Tracker

  • Contributor
  • Posts: 26
Re: bidirectional fibre tranceivers
« Reply #2 on: October 21, 2021, 11:12:47 am »
No, same fibre. The modules I have seen use two different wavelength lasers and obviously have internal beam splitters etc...

Just surprised the modules are not available to interface to directly for OEM use!

https://www.google.com/search?q=Bidirectional+SFP+Transceiver&rlz=1C1CHBD_en-GBGB795GB795&oq=Bidirectional+SFP+Transceiver&aqs=chrome..69i57j69i61l3&sourceid=chrome&ie=UTF-8
 

Offline mikerj

  • Super Contributor
  • ***
  • Posts: 2907
  • Country: gb
Re: bidirectional fibre tranceivers
« Reply #3 on: October 21, 2021, 01:07:11 pm »
The keyword you are looking for is "BOSA" Bi-directional Optical Sub-Assembly.  I very much doubt you are going to find one with a UART output though.

http://www.eoptolink.com/product-solutions/osa/bosa
 

Offline jeremy

  • Super Contributor
  • ***
  • Posts: 1071
  • Country: au
Re: bidirectional fibre tranceivers
« Reply #4 on: October 21, 2021, 01:10:06 pm »
Yes, you can buy these at the local computer supply store now, even TP-Link make them.

I don’t know of any that are non-SFP unfortunately, but I would like to know if anyone finds them. Usually SFP modules I have played with (dual fibre) can be used way below their rated data rate though, so it may work for you; for example, a 4Gbps module from Finisar worked fine with a 10MHz square wave.
 

Offline NiHaoMike

  • Super Contributor
  • ***
  • Posts: 8079
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: bidirectional fibre tranceivers
« Reply #5 on: October 21, 2021, 01:11:33 pm »
Have you considered multiplexing multiple links into a single higher bandwidth link? Ethernet switches with VLAN would be one way, but if the application is really latency sensitive, a pair of small FPGA boards could also work.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline Renate

  • Super Contributor
  • ***
  • Posts: 1462
  • Country: us
Re: bidirectional fibre tranceivers
« Reply #6 on: October 21, 2021, 08:17:53 pm »
Hey! I was wondering the same thing, but not full duplex, only half duplex.
I thought a drop-in RS-485 would be cool. I was originally thinking that 1mm plastic fiber for short distances.
Still, even a one way transmitter or receiver costs $10!
 

Offline daddario

  • Regular Contributor
  • *
  • Posts: 59
  • Country: ee
Re: bidirectional fibre tranceivers
« Reply #7 on: October 21, 2021, 08:33:28 pm »
In networking gear how it's done is using different wavelengths - be it bidirectional, or BIDI as it's called in the trade, using two wavelengths from the 1310~1550nm range (on one side it'll have, for example, a 1310nm transmitter, a 1490nm receiver and vice-versa on the other side) optically coupled together. Or CWDM/WDWM technology that uses tens of different wavelengths on a single fibre and (de)multiplexed together in an external optics units - in all those cases the active parts themselves have their unique WL. If your product is low-volume the cheapest option would be to buy CWDM SFP modules and rip the optics and transducers out.
Mind you that technology is intended for single-mode fibre (9/125um), but for very short distances any ol' plastic straw will do.
My competence in HF electronics over 30MHz rolls off 3dB/oct.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf