From my research, I have been having a tough time finding and specifying a fiber optic selector switch or multiplexer. Do fiber optic selector switches exist?

Background - Simple

I have an application with a not-cheap sensor that does the following:

  1. Sensor emits light
  2. Light travels and hits an object
  3. The object absorbs some of the light, and also reflects some back
  4. Sensor receives returned light
  5. Sensor processes the change and reports a sensed value

You can have the object be far away from the sensor via the use of a fiber optic cable. I do so, and it works great.

As a cost savings, I would like to have one sensor be able to senses from multiple different objects. This can be done using a bunch of fiber optic cables and a fiber optic selector switch or a multiplexer.

Background - Detailed

To be more detailed:

  • Sensor is a pH sensor, EOM-pH-mini.
  • Object is a small pH sensor spot, SP-HP5
  • Fiber optic cable is polymer, POF

Diagram of Fiber Optics


Does anyone here have experience in this area? In case you can't tell, I have none. Can you please provide insight into:

  • Suggestions of fiber optic selector switches
  • Important parameters in specifying the switch
  • If this is even possible?

Thank you in advance for your help!

  • \$\begingroup\$ perhaps you can build one ... small box containing a rotating mirror ... the mirror is mounted on a servo motor shaft .... or a sliding carriage that holds the end of a fiberoptic cable ... leadscrew moves the carriage and aligns the fiber with one of the other fibers .... you can actually test the concept by using a cardboard box and some foam blocks .... you could combine the sliding and rotating concepts into one ... google railway roundhouse \$\endgroup\$ – jsotola Jul 13 at 23:16
  • \$\begingroup\$ This seems like a great idea but the optical losses (in practice) in the switch make potential reduction in cost by saving fibre impractical. The cost of the fibre is usually much, much less than the cost of the lost photons. \$\endgroup\$ – D Duck Jul 13 at 23:26
  • \$\begingroup\$ If they do exist, they will probably be more than 1k$ as the fiber com muxes start at 1-2k$. Most fiber muxes are for a specific com wavelength and not for the wavelength of your PH sensor. Your probably better off with multiple sensors. \$\endgroup\$ – Voltage Spike Jul 13 at 23:33
  • \$\begingroup\$ @jsotola actually your comment on the sliding carriage with the lead screw idea is what we do. We actually currently have the sensor mounted on a linear rail, and move it between optic cables. However, this is sort of added complexity/footprint/time to move the rail between optic cables. In my opinion, a switch would be smaller footprint, easier to control, and generally cleaner. \$\endgroup\$ – Intrastellar Explorer Jul 13 at 23:39
  • \$\begingroup\$ @DDuck thank you for the warning, I don't have much experience in fiber optics. I wasn't aware that a switch could have this problem. \$\endgroup\$ – Intrastellar Explorer Jul 13 at 23:40

Yes, this product exists.

It can be made using MEMS technology, as an electromechanical device (a relay with a fiber attached to the armature), or motorized (and probably other technologies).

Important characteristics are

  • fiber type compatibility (single-mode or multi-mode, and what core diameter)

  • insertion loss

  • return loss

  • wavelength compatibility

  • number of inputs and outputs

  • switching cycle durability

  • power consumption

  • switching speed

  • control interface

  • ...

There are numerous vendors for these products. You can start searching them by looking in trade magazines like Laser Focus World and Photonics Spectra, or from exhibitor lists at trade shows like OFC (Optical Fiber Conference) and Photonics West.

  • \$\begingroup\$ Can you suggest any model, PN's, or manufacturers that might be a good starting point in a search @ThePhoton? Also, I will do some more searching based on the information you provided! \$\endgroup\$ – Intrastellar Explorer Jul 13 at 23:57
  • 1
    \$\begingroup\$ @IntrastellarExplorer, Sorry, product recommendations are off topic. Also, I don't work with POF, so I don't know which vendors might have this product for POF. \$\endgroup\$ – The Photon Jul 14 at 0:00
  • \$\begingroup\$ Considering OP only incurs 6dB of attenuation that way and doesn't seem to care about polarization, why not simply split into four and add LCD-based attenuators that "blacken out" three out of four? \$\endgroup\$ – Marcus Müller Jul 14 at 10:16
  • \$\begingroup\$ It looks like it's a reflective sensor, so you would take the loss hit on both passes. A perfect 1:4 split would cost 6dB in each direction, double that is 12dB, which might be too much. \$\endgroup\$ – alex.forencich Jul 14 at 19:22
  • \$\begingroup\$ @MarcusMüller what is OP? Also, I like the idea, not bad thinking!! I am also not sure how it would work with 6dB or 12dB loss. Could be worth a shot! \$\endgroup\$ – Intrastellar Explorer Jul 14 at 21:32

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