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Fiber optic Power/Link tester

One tester for determination optical signal speed, wavelength and power.

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4 in 1 Uuups ! It's now 5 in 1!
Only one device for fiber optic power measuring, 1310/1550 wavelenght detecting, 100/1000 Mbps signal speed detecting, link tester and laser source.

Working as Fiber optic technician for about 10 years in telecomunications I every day use Power meter as first test in fiber optics (FO). Depending on it's displayed values I decide what next I will do, or just test the link, or I'll connect Light source (LS) or Visible light sourse (VLS). Or the last step I'll use OTDR (optical time domain reflectometer), but this is absolutley another story of troubleshooting, which I will not describe here (but if someone is interested I can share my experience) :)))

What is this for device?
How does it works?
Which specifications it can support?
Why I (and others) need it?
What else I want to integrate in?

P.S. Also thanks for @oakkar7 with his project #Optical Power Meter (with SFP and DDM protocol) for some inspiration and some docume

Before all are safety! - Laser safety

  • What is this for device? 

This test device is for the first in field test.

It can fast detect: optical power, 

detect wavelenght (1310nm or 1550nm), 

test link (if other side connected to SFP or media converter (MC)) 100/1000Mbps for one or two fibers link,

work as callibrated light source CW (continuous wave) or modulated.

  • How does it works? 

The thest decice have 3 optical ports,

First port for optical power, wavelenght and link tester

Connected optical power goes through PLC splitter (Planar Lightwave Circuit) 1/2 with 50/50% insertion loss (what is approximately ≤4.0dB) to FWDM (Filter Wavelength Division Multiplexer) and to the 1x4 opto-mechanical switch (next OMswitch). By default OMswitch switched to the port which is not connected, to prevent SFP failure if obtained hight optical power. FWDM splits signals to 1310nm and 1550nm and each splitted signal connected to the InGaAs photodiode. Each photodiode connected to microcontroller throught OpAmps. 

So when microcontroller detects signal from one of photodiodes and if this signal will not be higher as -2dBm, microcontroller will switch OMswitch to defined SFP 1310 or 1550 or 2fiber (if detected signal will be from 1550nm photodiode - will be switched to 1550 SFP, if detected from 1310nm - will be switched first to the 1310 or to 2 fiber SFP). 

Next step is detecting link speed (if other side connected to SFP or to MC). This stage are realised throught integrated into SFP DDM (Digital Diagnostic Monitoring). DDM can show us not only tranceiver temperature, supply voltage, laser bias current, transmited average optical power, recieved optical modulation amplitude (OMA) or Average Optical Power, but also by received code detect link speed and identificate SFP or MC connected at the other end of the fiber.

Second port, tx port

This port is for 2 fibers SFP tx link testing. On display will be showed when received signal is 1310nm and microcontroller through 1310 SFP DDM will receiv identification information what other side SFP or MC use 2 fiber link, microcontroller will switch OMswitch to it's 5-th port and wait for connectind second (TX) optical fiber for link testing.

Third port, optical laser source

Wery often need to determinate/identificate correct fiber port in ODF (optical distribution frame). The laser source can work in 1310/1550nm and can be switched to CW or as modulated with different modulation frequency.

  • Which specifications it can support? 

The Device can messure high optical power from -50 up to ~+26dBm (Safety Class 1M)

Display resolution 0.01dB

Frequency Indentification Range <10KHz

Stabilized laser source 1310/1550nm (switchable) with output Power -7dBm to 0dBm (Safety Class 1)

Modulation Frequency: CW / 270Hz / 1KHz / 2KHz

USB connectivity

Memory

  • Why I (and others) need it? 

This Power Meter can help to fiber optic technicians and other persons who working with fiber optics links, to identificate fiber, test links and determinate configurated link speed, identificate other side installed transcievers...

  • What else I want to integrate in?

Else in my "every day working" I'm using VLS for fiber identification and fault location.

And I'm thinking about module which can determinate CATV 1310/1550nm signals.


Ideas and commensts are welcome ;)

Adobe Portable Document Format - 186.63 kB - 04/16/2018 at 15:07

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Mechanical switches.jpg

Opto-Mechanical switches

JPEG Image - 88.66 kB - 04/16/2018 at 11:27

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SFF-8472-(Diagnostic Monitoring Interface).pdf

SFF-8472 Specification for Diagnostic Monitoring Interface for Optical Transceivers

Adobe Portable Document Format - 170.48 kB - 04/16/2018 at 11:26

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an-2030_ddmi_for_sfp_rev_e2-20140404_updated.pdf

Application Note AN-2030 for Digital Diagnostic Monitoring Interface for SFP and SFP+ Optical Transceivers

Adobe Portable Document Format - 300.83 kB - 04/16/2018 at 11:25

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AiO Power meter.pdf

Structured scheme of universal All in One Fiber optic power meter

Adobe Portable Document Format - 36.10 kB - 04/13/2018 at 14:05

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  • Counting needed pins on MCU

    Alex04/23/2018 at 09:39 0 comments

    It's time to count all pins to select MCU.

    For every SFP DDM needed 3 pins, summary it's 9 pins. 

    InGaAs photodiode needs 2 pins, summary 4 pins. 

    Laser diode driver needs 1 pin. 

    Two Opto-Mechanical switch needs 8 pins each.

    Control buttons - 4 pins. 

    Display spi - 5 pins. 

    So summary I need from MCU minimum 40 pins.

    For making economy on MCU pinnouts, I think to use multiplexors for SFP and for switches. 

    Working now on mux selection... 

  • Opto-mechanical switch selection

    Alex04/19/2018 at 13:01 0 comments

    Opto-mechanical switch 1x4

    Buying 1x4 is much more expensive as buy one 1x2 plus one D2x2

    The price difference is aproximately twice! That's why for the first prototype I'll select second switching variant. And taking into account the simultaneous switching, switching time will be the same as at only one switch.

  • Passive component selection

    Alex04/18/2018 at 13:16 0 comments

    1. 1x2 PLC Fiber Splitter (from FS.COM)

    Short description:

    • Fiber type - singlemode G.657A1;
    • Insertion Loss - ≤4.0dB;
    • Return Loss - ≥50dB;
    • Temperature Dependent Loss - ≤0.5dB;
    • Operating Bandwidth - 1260~1650nm.

    2. FWDM Filter Wavelength Division Multiplexer FTTH/FTTX 1310/1550/1490nm (from FS.COM)

    Short description:

    • Fiber type - singlemode;
    • Return Loss - > 45dB;
    • Passband Ripple - < 0.3dB;
    • Operating Bandwidth - 1310/1550nm.

    3. InGaAs PIN Photodiode for Optical Power Meter (from oemarket.com)

    Short description:

    4. Dual Wavelength Laser Combiner Module

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