SFP Module Selection Guide
SL Optic uses two SFP slots — SFP 1/2 and SFP 3/4 — each covering two optical channels. SFP modules are not included and must be ordered separately.
This page explains how to choose the right module type. For the list of tested and compatible modules, see Supported SFP Modules.
Why Standard Network SFPs Will Not Work
This is the most common mistake when sourcing modules for SL Optic. A standard 1G or 10G network SFP looks identical but fails for two fundamental reasons:
1. Data Rate
SDI video operates at much higher bitrates than standard networking SFPs support:
| SDI Standard | Bitrate | Typical Network SFP Max |
|---|---|---|
| SD-SDI | 270 Mbit/s | ✓ In range |
| HD-SDI | 1.485 Gbit/s | ✓ May work |
| 3G-SDI | 2.97 Gbit/s | ✗ Exceeds 1G SFP limit |
| 6G-SDI | 5.94 Gbit/s | ✗ Far exceeds |
| 12G-SDI | 11.88 Gbit/s | ✗ Far exceeds |
A standard 1.25G Gigabit Ethernet SFP cannot handle 3G-SDI or higher. Even if it physically fits and links up, the signal will not pass correctly. You need modules explicitly rated for SDI video — look for the labels "3G-SDI", "12G-SDI", or "SDI Video SFP" in the product name.
2. Optical Port Configuration
Each SFP slot in SL Optic carries two independent SDI channels. A standard duplex LC SFP has one TX and one RX port — this means it can only handle one bidirectional link, not two independent channels.
For SL Optic you need dual-channel video SFP modules — modules with two independent optical ports in a single SFP housing. There are three types, and the correct one depends on the direction of the two channels in that slot:
| Type | Ports | Use when... |
|---|---|---|
| Dual transmitter (2O) | 2× TX, no RX | Both channels in the slot send SDI → optical |
| Dual receiver (2I) | 2× RX, no TX | Both channels in the slot receive optical → SDI |
| Bidirectional (IO) | 1× TX + 1× RX | One channel sends, one receives in the same slot |
Display Screen 2 shows which type is recommended for each slot based on the current DIP switch settings (2O, 2I, or IO).
Each SFP slot handles 2 channels, so 2 modules cover all 4 channels of the device.
Choosing the Right Module
Step 1 — Determine channel directions
Check your DIP switch configuration. Display Screen 2 shows the recommended module type (IO, 2I, 2O) for each slot based on the current settings.
| DIP switch state | SFP slot needed |
|---|---|
| Both channels In (SDI→optical) | Dual transmitter (2O) |
| Both channels Out (optical→SDI) | Dual receiver (2I) |
| One In, one Out (mixed) | Bidirectional (IO) |
Step 2 — Determine fiber type and distance
| Distance | Fiber | Wavelength range |
|---|---|---|
| Up to 300 m | Multi-mode (OM3/OM4) | 850 nm |
| Up to 10 km | Single-mode (OS2) | 1310 nm |
| Up to 20–40 km | Single-mode (OS2) | 1310 nm / 1550 nm |
| Up to 60 km | Single-mode (OS2) | 1550 nm |
For nearly all broadcast infrastructure deployments, single-mode fiber at 1310 nm is the standard choice.
Step 3 — Decide on CWDM (optional)
If you want to carry multiple SDI channels over a single fiber strand, use CWDM modules with a matching MUX/DEMUX at each end. CWDM wavelengths are spaced 20 nm apart (1271–1611 nm), allowing up to 8 channels per fiber pair.
See SFP Modules — CWDM for a diagram and explanation.
CWDM — Multiple Channels Over One Fiber
SL Optic supports CWDM SFP modules, allowing multiple SDI channels to share a single fiber strand.
Each SFP is assigned a distinct wavelength. A CWDM MUX/DEMUX at each end of the fiber combines and separates the wavelengths. CWDM wavelengths used for SDI video are typically in the 1271–1611 nm range.
CWDM requires matching equipment at both ends
CWDM modules only work when paired with a CWDM MUX/DEMUX whose channel plan matches the wavelengths of your SFP modules. Contact Stream Labs or your fiber infrastructure supplier for planning assistance.
DDMI Support
Modules with DDMI (Digital Diagnostics Monitoring Interface, also called DOM) report optical TX and RX power levels to the device. These values appear on display Screens 3 and 4, making it easy to verify link health without external test equipment.
Modules without DDMI still pass signals correctly but show 00001 for power readings on the affected ports.
Inserting and Removing Modules
Modules are hot-swappable. To insert, slide the module into the SFP slot until it clicks. To remove, release the latch mechanism and slide the module out.
Warning
Always fit the dust cap to any SFP port or module when no fiber is connected, to protect the optical surfaces.