Click Fraud
Nov
17
2014
PMMA-SI-POF common characteristics

Most common type of POF is the 980 μm core PMMA-SI-POF. It gets its spread by implementation in video surveillance, car, and home networking systems. Its main advantages are mechanical:

 

 

  • Bending and stressing – material is flexible enough to withstand rough handling (which is useful for brownfield installations);
  • Tolerance – dust on the ends of the fiber is not disturbing signal as much as it does in other fibers;
  • Simple tool tolerance – fiber can be cut with ordinary scissors and polished with sandpaper;
  • Low skill installation/maintenance – since the signal sources are visible, installation is easier for unskilled personnel and/or users, which allows to reduce initial cost. Additionally, it is easier to troubleshoot the signal, when the signal wavelength is visible;
  • Water tolerance – PMMA can be used in salt and non-salt water.

 

All those mechanical advantages are achieved with a price of bandwidth loss and attenuation increase. Bandwidth limitation happens due to core size, while attenuation – due to material. PMMA-SI-POF is positioned as the copper competitor, which can be used in hostile environments.

 

Signal attenuation spectrum suggests three transmission windows:

 

  • 480 nm – blue;
  • 520 nm – green;
  • 650 nm – red.

 

Additional attenuation might appear due to bend. In fact, every 10 mm bend radius gives +0,5dB attenuation, with no extra attenuation after 25 mm.

 

Most common optical source for PMMA-SI-POF is the LED, due to high power output and long lifetime. LEDs are available in all colors, however, red leds have higher bandwidth compared to green ones.

 

Table 1. Sources for 1 mm PMMA-POF
 

Sources Wavelength (nm) Peak Output Power (mW) Numerical Aperture Electrical BW (MHz)
LED Blue

460

5

0.5

10

LED Green

520

3

0.5

10

LED Red

650

1

0.5

100

RCLED

650

0.7

0.35

400

LASER

655

12

0.25

0.1

VCSEL

665

0.3

0.25

0.1

 

Increased bandwidth can be provided by RC-LEDs (Resomant Cavity LEDs). They can offer spectral width of 20 nm at 650 nm. Table 1 provides list of LED sources the can be used for PMMA-SI-POF. Photodiodes can be used instead of LEDs in PMMA-SI-POF. List of available photodiodes can be found in Table 2.

 

Table 2. Photodiodes for 1 mm PMMA-POF
 

Photodiodes

Peak Responsivity Wavelength (at R max) (nm)

Responsivity at

Active Area (mm2)

Electrical BW (MHz)

Peak

Red

Green

APD

920

0.6

0.35

0.2

0.2

500

PIN

820

0.6

0.45

0.3

0.36

125

Ga-As

850

0.6

0.21

1

1500

Testimonials

Lomoveishiy – Finland

I needed those to connect my PC on the third floor to have internet access in that room, and ISP installed their modem on the first floor only. After dropping fiber patch cables, plugged in all cables into these media converters at both sides, and link came up instantly. Was much easier than I thought!

Raymond – USA

Great experience – units worked straight out of the box – just needed plug in cables and we were done. I also like the possibility to enable jumbo frames, while we do not have a need for this feature at the current moment it’s great to have this option.