Fibre Optic Patch Cords Explained: OS2 vs OM3/OM4, UPC vs APC, and How to Choose (Pakistan Guide)
Choosing the right fibre optic patch cord looks simple until you face a shelf of yellow and aqua cables with blue and green connectors. Pick the wrong one and your link will not light up, or it will run with high loss. This guide explains OS2 vs OM3/OM4, UPC vs APC and the connector types, so engineers, ISPs and network installers in Pakistan can order the right cord the first time.
What is a fibre optic patch cord?
A patch cord (also called a patch cable or jumper) is a short length of fibre cable with a connector fitted at each end. It links equipment such as switches, routers, ONTs, OLTs and media converters to patch panels, ODFs and termination boxes. A patch cord has three parts you need to choose: the fibre type, the connector type and the polish (UPC or APC). You also choose simplex or duplex and the length.
Single-mode OS2 vs multimode OM3 and OM4
OS2 single-mode
OS2 cords use a 9/125 µm single-mode fibre and work at 1310 nm and 1550 nm. Because the core is tiny, light travels in one path, which allows distances of many kilometres. OS2 is the standard for FTTH, GPON, ISP backbones and links between buildings. The jacket is usually yellow.
OM3 and OM4 multimode
OM3 and OM4 use a larger 50/125 µm multimode fibre, optimised for 850 nm lasers. They are used for short links inside data centres and server rooms. For 10G Ethernet (10GBASE-SR), OM3 reaches about 300 m and OM4 about 400 m. The jacket is usually aqua. Multimode transceivers are cheaper, but the distance is limited.
Golden rule: the patch cord must match the fibre type of your network and your transceivers. Never mix single-mode and multimode on the same link.
UPC vs APC polish
The polish describes how the end face of the connector ferrule is finished.
- UPC (Ultra Physical Contact): flat, slightly domed end face. Connector body is usually blue on single-mode cords. Used widely in Ethernet, switches and data networks.
- APC (Angled Physical Contact): the end face is polished at an 8° angle, so reflected light is sent into the cladding instead of back to the source. This gives much lower back reflection. The connector body is green. APC is the usual choice for GPON/FTTH and video (CATV) networks.
An APC connector must only mate with another APC, and UPC with UPC. Joining the two causes high loss and can damage the end faces.
Quick comparison table
| Type | Fibre | Wavelength | Typical colour | Best for |
|---|---|---|---|---|
| OS2 single-mode | 9/125 µm | 1310 / 1550 nm | Yellow jacket | FTTH, GPON, ISP, long links |
| OM3 multimode | 50/125 µm | 850 nm | Aqua jacket | 10G up to ~300 m |
| OM4 multimode | 50/125 µm | 850 nm | Aqua jacket | 10G up to ~400 m, data centres |
| UPC polish | Any | – | Blue connector (SM) | Ethernet, switches, routers |
| APC polish | Single-mode | – | Green connector | GPON, FTTH, CATV |
LC vs SC connectors, simplex vs duplex
Connector types
SC is a larger push-pull square connector, common on ODFs, splitters and GPON equipment. LC is a small form-factor connector, about half the size, used on SFP transceivers and high-density patch panels. If the two ends of your link use different ports, choose a hybrid cord such as LC to SC.
Simplex or duplex
A simplex cord has one fibre, used for bidirectional (BiDi) optics and GPON ONTs. A duplex cord has two fibres, one to transmit and one to receive, which is what most standard SFP links need.
How to choose the right patch cord: 5 steps
- Check the fibre type printed on your transceiver or existing cable: single-mode (OS2) or multimode (OM3/OM4).
- Check the polish: green connectors mean APC, blue (single-mode) means UPC. Match it exactly.
- Check the connector at each end: LC, SC or a mix.
- Choose simplex or duplex based on your equipment.
- Measure the length and add a little slack for neat cable management.
Litech patch cords: lengths, prices and delivery
Litech stocks OS2 single-mode and OM4 multimode patch cords in LC and SC, UPC and APC, simplex and duplex. Every cord is available in 1, 3, 5, 10 and 20 m. Prices start at Rs 775 for 1 m and add Rs 100 for each extra metre (3 m Rs 975, 5 m Rs 1,175, 10 m Rs 1,675, 20 m Rs 2,675). Prices include 16% tax, and each cord is individually bagged and labelled.
Popular choices:
- SC APC to SC APC Duplex OS2 patch cable for GPON and FTTH
- LC UPC to SC UPC Duplex OS2 patch cable for SFP to ODF links
- LC UPC to LC UPC Duplex OM4 patch cable for data centres
Browse the full range in Fibre Patch Cords and Patch Cables, or download datasheets from our E-Catalog.
Frequently asked questions
Can I connect an APC cord to a UPC port?
No. APC and UPC end faces are different shapes. Mating them causes high insertion loss and can damage the connectors. Always match APC to APC and UPC to UPC.
Which patch cord do I need for GPON or FTTH?
Most GPON and FTTH networks use OS2 single-mode with SC APC (green) connectors. Check the port on your ONT or splitter to confirm.
Can I use OM4 instead of OM3?
Yes. OM4 uses the same 50/125 µm fibre and connectors as OM3 and is backward compatible, with longer reach at high speeds.
How long does delivery take in Pakistan?
Delivery is free across Pakistan in 5–7 working days. Payment is by bank transfer.
Need help choosing?
Not sure which cord fits your equipment? Send us a photo of your port on WhatsApp +92 313 7776766 or email info@litech.com.pk, and our team will recommend the right patch cord. For bulk orders, ask us for a quote.
