Optical Node Unit (ONU) for RFoG networks


About the Product

The Light Link® DPON-SD2 is the Optical Node Unit (ONU) for new “RFoG” (RF over Glass) Fibre-to-the-Home (FTTH) architecture, and is optimized to work over PON standards-compliant FTTH networks. The Society of Cable Telecommunications Engineers has issued their standard document IPS SP 910 to cover the subject and set implementation guidelines.

Rolling out RFoG makes it possible for a cable operator to continue the deployment of DOCSIS-compliant cable modems for Internet and Telephony delivery, together with Video on Demand systems which need an RF return path to operate. The DPON-SD2 optical node looks just like an HFC network for all of the traditional customer premises equipment.

The DPON-SD2 is designed for 1550 nm forward-path RF signals, with return-path RF signals converted to optical at either 1310 nm or 1610 nm in a 1x32 split FTTH network topology.

The DPON-SD2 incorporates an isolated DFB optical laser to modulate the return-path signal from DOCSIS modem onto the fiber. The photodiode featured on the duplex model provides a 1550 nm CATV receiver with a forward path frequency response up to 1003 MHz.

An optional CWDM combines these forward and return-path signals across a 1310/1490 nm EPON/GPON network, offering a transitional platform to migrate existing HFC two-way STB and DOCSIS modem technology to PON FTTH.

Employing leading edge system design, the DPON-SD2 is a must-have in any FTTx/CATV solution. The power of having a Passive Optical Network (PON), but still allowing an RF overlay, offers a multi-functional PON delivering more services over the same infrastructure.

  • Suitable for transmission of PAL and NTSC analog TV channels as well as DVB-C and DVB-T digital television standards
  • Active Carrier Suppression (ACS) to allow up to 32 units to function within a PON HFC network compatible with DOCSIS 1, 2 or 3 standards, and with SCTE-standards SCTE-174-2010 for RFoG
  • Support 10G xPON with build-in optical filter
  • Powered directly using the power socket or via the F-type connectors
  • The compact and sturdy enclosure fits easily in wiring closets or network termination boxes
  • Specifically designed to be SCTE-174-2010 standards compliant
Forward Path Optical
Wavelength  1540~1565nm
Pass-through 1270/1310/1490/1577 nm
Input level -6 dBm to 0 dBm
Nominal network design input level:
-5 dBm
Optical input return loss > 45 dB
Forward Path RF
RF output level 20 dBmV (1), 36 dBmV
RF bandwidth 70 ~ 1218 MHz
85 ~ 1218 MHz
105 ~ 1218 MHz
204 ~ 1218 MHz
RF flatness ≤ ±1.0 dB
RF slope 4 ±1 dB 
RF output return loss > 16 dB 
RF output test point -20 dB
CNR > 47 dB
CSO < -60 dBc
CTB < -60 dBc
Equivalent input noise
current density(NCD)
< 5 pA/√Hz
Optical ALC range -6 +3 dBm
Optical input indicator
within range green, out of range off
Forward Path CNR (1)

(1) Measured in a typical 1550 nm transmission system with PBN A-FT5S optical transmitter and 5 km of single-mode fiber to the DPON-SD2, aligned for the recommended nominal optical input power of -5 dBm, with 42 Cenelec carriers and 4% OMI.
Relative Noise Bandwidth (RNB) 5 MHz for PAL television channels. CNR performance for NTSC television channels with 4 MHz RNB is 1 dB better.
Through loss for 1310 and 1490 nm is less than 1 dB.

Return Path Optical
Wavelength 1610 nm (Default)
CWDM (2)
Output level 1.5 dBm ±1 dB
3 dBm ±1 dB
5 dBm ±1 dB
Connectors SC/APC
Return loss > 45 dB
Relative intensity noise
< 145 dB/Hz
Return Path RF
RF bandwidth 12 ~ 55 MHz
5 ~ 65 MHz or 12 ~ 65 MHz
5 ~ 85 MHz or 12 ~ 85 MHz
5 ~ 105 MHz or 12 ~ 105 MHz
RF flatness ±1.0 dB
RF input return loss > 16 dB
RF input test point -20 dB
RF input range 10 ~ 40 dBmV (3)
RF threshold for ACS < 15 dBmV
Power at which the
R-ONU must turn on
laser must on: 10 ±2 dBmV
laser must off: -4 ±2 dBmV
External power supply 11 ~ 16 Vdc (4)
450 mA @ 12 Vdc
Optical connectors SC/APC
Power/RF connectors SCTE F-type
Power connector 2.1 mm DC socket
Operating temperature -20 ºC to +55 ºC
Operating humidity 5 % to 95 % (non-condensing)
Dimensions (H x W x D) 115 mm x 163 mm x 38 mm
Unit weight 0.38 kg
Power supply weight 0.22 kg
Shipping carton dimensions (contains 10 units) 170 mm x 530 mm x 380 mm
Shipping carton weight (contains 10 units) 7.7 kg (5)

(2) With Active Carrier Suppression enabled, laser optical power level is < -15 dBm when no RF input signal is applied.

(3) Internal adjustment optioned for installer. Factory set at 10% OMI with a 30 dBmV input.

(4) A universal mains plug-pack is supplied with the DPON unit. The plug-pack is suitable for 95 ~ 265 Vac, 50 ~ 60 Hz and has mains pins for AU/CN/EU/UK/US.

(5) DPON-SD2 optical receivers are supplied in bulk pack cartons of 10 units. Individual pack­aging can be provided on request at additional cost.

A-RRAG-Q-S-20 AIMA Analog Quad Return RX, RFoG, SC/APC.
F-FCHA-4U FIMA 19” Chassis, 4RU, 16 Slots.
F-OSF-1x08-L FIMA 1:8 Way optical splitter.
F-WDMM-08-0-2-xx-S FIMA DWDM MUX, 8 Ports, start ITUxx, 200 GHz, SC/APC.
F-WDMM-16-0-2-xx-L FIMA DWDM MUX, 16 Ports, start ITUxx, 200 GHz, LC/APC.
CWDM19-24RFOG61-LC 1RU CWDM, 24x RFoG/(G/E)PON with 1610 nm RFoG return and 1550 nm CATV overlay filters, LC/APC.
DPON-SD2-[U][VVV]-[WW][X]-[Y]-[ZZ] Optical Node Unit (ONU) for RFoG Network - Single Dwelling Unit (SDU)
0 No optical bypass port
G Optical bypass port for external EPON or GPON ONU on 1310/1490 nm
X Optical bypass port for external EPON, GPON,10G EPON or 10G GPON ONU on 1270/1310/1490/1577 nm
VVV Frequency
0 Forward-path receiver only, no diplexer
42A 5-42 / 54-1218 MHz RF diplexer
65A 5~65 / 85~1218 MHz RF diplexer
85A 5~85 / 105~1218 MHz RF diplexer
24A 5~204 / 258~1218 MHz RF diplexer
55B 12~55 / 70~1218 MHz RF diplexer
65B 12~65 / 85~1218 MHz RF diplexer
85B 12~85 / 105~1218 MHz RF diplexer
24B 12~204 / 258~1218 MHz RF diplexer
WW Return Path Laser Transmitter
0 Forward-path receiver only, no return-path transmitter
29 Isolated DFB laser 1290 nm
33 Isolated DFB laser 1330 nm
35 Isolated DFB laser 1350 nm
37 Isolated DFB laser 1370 nm
39 Isolated DFB laser 1390 nm
41 Isolated DFB laser 1410 nm
43 Isolated DFB laser 1430 nm
45 Isolated DFB laser 1450 nm
47 Isolated DFB laser 1470 nm
51 Isolated DFB laser 1510 nm (1)
53 Isolated DFB laser 1530 nm (1)
59 Isolated DFB laser 1590 nm (1)
61 Isolated DFB laser 1610 nm
X Return Path Optical Power Output
N Forward-path receiver only, no return-path transmitter
1 1.5 dBm ±1 dB
3 3 dBm ±1 dB
5 5 dBm ±1 dB
Y Forward Path RF Output Level
1 20 dBmV at 1218 MHz
2 36 dBmV at 1218 MHz
ZZ Power Supply (2)
C PS121500-CB: With universal 12 Vdc power supply plug-pack with providing power through coaxial cabling, suitable for 95~265 Vac, 50~60 Hz with interchangeable mains pins for AU/CN/EU/UK/US
6C 35-95 Vac to 12 Vdc power supply, coaxial cable in and coaxial cable out
EU 95~265 Vac to 12 Vdc power supply, European adaptor
US 95~265 Vac to 12 Vdc power supply, American adaptor
UK 95~265 Vac to 12 Vdc power supply, United Kingdom adaptor
AU 95~265 Vac to 12 Vdc power supply, Australian adaptor
CN 95~265 Vac to 12 Vdc power supply, Chinese adaptor
CH 95~265 Vac to 12 Vdc power supply, Switzerland adaptor


(1) Will not BOSA laser technology, the price will different with other wavelength.
(2) Additional country-specific adapters are available upon request.

  • DPON