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