No light detected from 1310 nm IR optical transceiver AFBR-5813TQZ

Question

I am trying to build a test application circuit for an AFBR-5813TQZ IR (1300 nm) optical transceiver. For now, I am only trying to verify that the transmitter works, so I have breadboarded the recommended application circuit from the datasheet, fed 3.3V into Vcc from one power supply, and fed 1V across TD+ and TD- from another power supply with separate grounding via a twisted cable (LVDS). The voltage values were obtained from the recommended operating conditions section of the datasheet.

I am detecting light power output with a lab bench power meter and a short plastic optical fiber cable. However, I do not detect anything when the circuit is powered. I am reasonably sure that the detector and connecting fiber is not at fault because I successfully detect the output of a similar setup with a AFBR-5972EZ (650 nm) optical transceiver and the appropriate settings.

I have verified and remade my breadboard circuit connections multiple times now, so I am reasonably sure I have built the recommended application circuit as specified. Probing the pins of the transceiver also yields voltages I would expect, about 3.3V on Vcc, +0.5V on TD+, and -0.5V on TD-, with respect to the ground of the Vcc power supply. I have multiple copies of the transceiver component as well, so I do not think it is a faulty component causing the issue.

I have frankly never used optical transceivers before, so I am not sure how to proceed. Unfortunately, I do not have another IR source at my disposal to test the detector. I would appreciate any suggestions or advice and can provide more information on my setup if requested. Thanks!

EDIT: I am editing my post to provide more information on my light detection. I am using a 1936-R Newport Optical Power Meter. I used a 400-1100 nm detector to detect the 650 nm light and a 780-1800 nm detector to detect the IR light. For both optical connections, I use the same 1m optical patch cable from Fibertronics. From the datasheet, it uses Corning SMF28 fiber, which seems to be rated for IR wavelengths.

Answer 1

Welcome to EE.SE.

You've given us specifications for three different types of fibre optic cable; only one of which is likely to work properly.

In the body of your question you mention plastic fibre. This will generally only work at visible wavelengths (1, 2, 3) so will be no good at 1310 nm.

You also mention Corning SMF-28 optical fibre. This is single mode fibre with a core diameter of 9 μm at 1310 nm λ. Your Broadcom transceiver is intended to work with 50-μm or 62.5-μm core multimode fiber so you'll only couple a small amount of light into a single core fibre. However your detector seems sensitive enough to cope with this (sensitivity of 5 nW or -53 dBm).

The patch cord you linked to, item no: PC-SS6D30V01M, has a data sheet that covers a whole range of different cable types. If you actually have the Corning InfiniCor OM1 62.5/125μm multimode fibre corresponding to that item number it should be fine for 1310 nm.

So what cable do you actually have? Is there a type number printed on the fibre jacket that you can check? If not you might be better off getting a glass fibre patch cord with the correct wavelength range.

Also note the warning in the datasheet of your IR transceiver that:

The input of the transmitter sections is internally
AC-coupled and terminated. If a DC signal is received, there
is no light output.

You'll need to provide a data signal (or a pulse train looking sufficiently like a data signal) to get any IR light out of your transceiver. I note you've been able to get the visible light transceiver to work. However this has a different pinout and signals so making this work doesn't necessarily mean the IR version will work with your supporting circuitry.