What is the difference between GPON and EPON?

GPON offers higher downstream bandwidth and better QoS. EPON provides symmetric bandwidth at lower cost. GPON supports split ratios up to 1:128 for wider coverage.

Which ONU/ONT is compatible with my OLT?

Our L880G and L801 series ONUs support XPON dual-mode and work with Huawei, ZTE, FiberHome and other major OLT brands. Contact support to confirm compatibility.

What is the difference between SC/APC and SC/UPC connectors?

SC/APC (Angled Physical Contact) and SC/UPC (Ultra Physical Contact) are two common fiber optic connector polish types. The key difference is the end-face angle.SC/UPC: Flat end-face with slight curve, return loss ≥50dB. Used for general-purpose data transmission. Blue color.SC/APC: 8° angled end-face, return loss ≥60dB. Used for RF video transmission (CATV) and PON networks. Green color.They are NOT interchangeable — mixing them can damage the connector end-face.

How do I choose the right fiber optic splitter for my network?

Choosing the right fiber optic splitter depends on several factors:Type: PLC splitters offer better performance for FTTx; FBT splitters suit smaller setupsRatio: Common ratios: 1×2, 1×4, 1×8, 1×16, 1×32, 1×64Package: ABS box (indoor), Mini steel tube (tight spaces), LGX cassette (rack mount)Connector: SC/APC for CATV, SC/UPC for dataFor GPON/EPON FTTH deployments, a 1×8 or 1×16 PLC splitter with SC/APC connectors is recommended.

What is the maximum distance for fiber optic transmission?

Fiber optic transmission distance depends on fiber type and equipment:Single-mode fiber (OS2): Up to 40km+ without amplificationMulti-mode fiber (OM1-OM5): 300m to 550m at 10GbpsGPON: Typically 20km reachEPON: Typically 20kmXGS-PON: Up to 40km1550nm wavelength has lower attenuation (≈0.2dB/km) vs 1310nm (≈0.35dB/km). For standard GPON FTTH, 20km is typical from OLT to ONU.

How do I configure an ONU/ONT for my fiber network?

Configuring an ONU/ONT involves these steps:Connect: Plug fiber cable into PON port, Ethernet to your router/PCPower on: Wait for PON LED to turn solid (optical signal received)Access web: Set PC to same subnet (192.168.1.x), open ONU IP (usually 192.168.1.1)Configure WAN: Set connection type (PPPoE, DHCP, or Static IP) per ISP requirementsRegister: Some ISPs require registration via serial number, LOID password, or MAC address

What is XGS-PON and how is it different from GPON?

XGS-PON (10 Gigabit Symmetric PON) is the next-generation PON technology offering 10Gbps symmetric bandwidth. Key differences from GPON:Speed: GPON = 2.5Gbps down / 1.25Gbps up. XGS-PON = 10Gbps both directionsWavelength: XGS-PON uses 1577nm down / 1270nm up (different from GPON's 1490nm/1310nm)Coexistence: XGS-PON can share the same fiber with GPON via WDMXGS-PON ONUs work with dual-mode OLTs but need an XGS-PON port for 10G speeds. Ideal for 4K/8K streaming, cloud computing, and enterprise use.

How Many Homes Can One OLT Port Serve?

In GPON networks, one OLT port typically serves 32 to 128 homes, depending on the split ratio. A 1:32 splitter is most common for FTTH deployments. With XGS-PON, one port can serve 256+ subscribers. Actual capacity depends on bandwidth per user — if each user needs 100Mbps, a GPON port (2.5Gbps down) handles ~25 users at peak. For our 2-port EPON OLT (L202), each port supports up to 64 ONUs, giving a total of 128 homes per device.

How Is GPON Data Secured on Fiber Optic Networks?

GPON uses AES-128 encryption to secure downstream data. Each ONU receives only its own data — the OLT encrypts traffic with a unique key per ONU. Upstream data is inherently secure because each ONU transmits in its assigned time slot. AES encryption is enabled by default in most OLTs like our EPON/GPON models. For additional security, MAC address filtering and ONU authentication are supported.

Is Fiber Optic Cheaper Than Copper in the Long Run?

Yes. While fiber optic cabling costs 20-30% more upfront, its total cost of ownership (TCO) over 10 years is 40-60% lower than copper. Fiber supports 40Gbps+ bandwidth vs copper's 10Gbps limit, has 25+ year lifespan (copper: 5-10 years), and needs no signal repeaters for up to 40km. For ISPs, the breakeven point is typically 2-3 years. Our single-mode fiber patch cables and splitters provide reliable long-term infrastructure.

APC vs UPC Fiber Connector Guide: Differences & Selection

APC vs UPC Fiber Connector: Complete Guide to End Face Differences and Selection

29/04/2026 Langzhi Technology

A complete guide to APC and UPC fiber connector end face differences. Compare polish angles, return loss, insertion loss, applications, and learn why GPON/FTTH networks use APC while data centers use UPC.

What is a Fiber Connector End Face?

The fiber connector end face is the physical contact surface at the tip of the ferrule. Its polish shape and angle directly affect signal transmission quality. The two most common end face types are UPC (Ultra Physical Contact) and APC (Angled Physical Contact).

Understanding the difference between APC and UPC is essential for selecting the right fiber components and ensuring network performance.

UPC End Face Explained

UPC uses a micro-dome polish that creates a tight physical contact between fiber cores, minimizing air gaps and signal reflection.

Shape: Micro-dome (convex spherical)
Angle: 0° (perpendicular to fiber axis)
Return Loss: ≥50dB
Insertion Loss: ≤0.3dB
Color Code: Blue (typical)

Best for: Data centers, enterprise networks, high-speed Ethernet (10G/25G/40G/100G), SFP/SFP+ modules.

APC End Face Explained

APC uses an 8° angled polish. When two APC fibers connect, reflected light is directed into the fiber cladding rather than returning along the core, dramatically reducing return loss.

Shape: 8° angled
Angle: 8° (relative to fiber axis)
Return Loss: ≥60dB
Insertion Loss: ≤0.3dB
Color Code: Green (typical)

Best for: GPON/EPON FTTH networks, CATV, RF video, high-precision test equipment.

APC vs UPC: Key Parameter Comparison

Parameter	UPC	APC
Polish Angle	0° (micro-dome)	8° angled
Return Loss	≥50dB	≥60dB
Insertion Loss	≤0.3dB	≤0.3dB
Color Code	Blue	Green
Primary Use	Data centers, Ethernet	GPON/FTTH, CATV, RF
PC Compatible	Yes	No
Cost	Lower	Slightly higher

Why APC and UPC Cannot Be Mixed

NEVER directly connect APC and UPC connectors! The 8° angled APC surface cannot form proper physical contact with the 0° UPC dome, creating an air gap that causes high insertion loss, severe return loss reduction, and potential physical damage to the end faces.

If you must connect APC and UPC devices, use a hybrid adapter or a conversion patch cable.

How to Choose: APC vs UPC

Choose UPC For:

Data center cabling
Enterprise LAN
High-speed Ethernet
SFP/SFP+ transceivers

Choose APC For:

GPON/EPON FTTH networks
CATV networks
RF over Glass (RFoG)
OTDR and test equipment

Conclusion

APC and UPC are both excellent connector end face types, each optimized for different applications. UPC is ideal for data centers and enterprise networks, while APC is the industry standard for GPON/FTTH and CATV. Always use the same end face type throughout your network and NEVER mix APC and UPC. Langzhi Technology offers a full range of SC/APC, SC/UPC, FC/APC, and LC/UPC fiber patch cables and adapters.