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Fiber Optic Attenuator

Fixed fiber optic attenuators in LC, SC, FC, ST and MU — UPC or APC polish, single-mode or multimode, 1 dB to 25 dB (up to 30 dB on request). Built with metal-ion doped attenuating fiber for stable, wavelength-independent loss.

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Fixed Fiber Optic Attenuators 1~30dB

 

Fiber Optic Attenuators

What is a fiber optic attenuator?

A fiber optic attenuator is a passive device that reduces the power level of an optical signal by a controlled amount, measured in decibels (dB). It does the opposite of most fiber components: instead of minimizing loss, it deliberately adds a precise, repeatable amount of loss.

This matters because too much light is a problem. Every optical receiver has a working range — a minimum sensitivity and a maximum input power. Push the signal above that ceiling and the receiver saturates, producing distorted data, bit errors, and in extreme cases permanent damage to the photodetector. It happens on short links between high-power transmitters and sensitive receivers: data-center patch panels only metres apart, FTTH drops where the ONT sits close to the splitter, or a long-reach module pressed into service over a short jumper.

Fiber optic attenuators are used in two main ways — permanently installed in a link to match transmitter output to receiver input and protect the receiver for the life of the connection, or added temporarily for power-level testing, where a calibrated amount of loss measures a system's power margin. In multi-wavelength systems an attenuator also equalizes channel power, pulling stronger channels down to match weaker ones so the whole band stays balanced.

 

FOCC-fiber optic attenuator

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Fiber optic attenuator specifications

Real specifications for FOCC's two core fixed-attenuator families.

Parameter Male-to-Female · Plug-in type Female-to-Female · Flanged / adapter type
Connector LC, SC, FC, ST, MU LC, SC, FC, ST
Connector gender Fixed male-to-female Fixed female-to-female
Fiber mode Single-mode / Multimode Single-mode (multimode optional)
Attenuation value 1–25 dB (up to 30 dB optional) 1–25 dB, 1 dB increments
Polish type UPC / APC (PC optional) UPC / APC
Operating wavelength 1260–1620 nm (SM); 850 / 1310 nm (MM) 1260–1620 nm (SM)
Attenuation accuracy 1–9 dB ±0.5 dB; 10–25 dB ±10% 1–5 dB ±0.5 dB; 6–10 dB ±0.7 dB; >10 dB ±1.0 dB
Return loss UPC ≥55 dB / APC ≥60 dB UPC ≥65 dB / APC ≥60 dB
Polarization dependent loss ≤0.2 dB ≤0.2 dB
Max optical input power 200 mW 200 mW
Operating temperature −40 °C to +80 °C −40 °C to +75 °C
Storage temperature −40 °C to +85 °C −40 °C to +80 °C
Humidity ≤95% RH ≤95% RH
Attenuating element Metal-ion doped fiber Metal-ion doped fiber
Test report Optional, per unit on request Included with shipment

 

How to choose the right attenuator

 

Four factors to consider: decibel level, interface type, polishing level, and whether it's a fixed or variable type. The decibel level is the most critical—too low and the receiver will still overload, too high and the signal reception will be insufficient.

 

Step 1 — Calculate the attenuation value

The simplest field method uses an optical power meter:

Field method

Required attenuation = Measured received power − Target receiver input

 

Example. You measure −5 dBm at the receiver and it works best around −15 dBm → you need about 10 dB, so a 10 dB fixed attenuator is the right choice.

Link-budget method

Required attenuation = Tx output − Link loss − Target Rx input − Safety margin

Always leave a few dB of margin — real-world loss drifts with temperature and ageing. A common mistake is fitting a 10 dB part where 5 dB was needed, then watching the link drop once environmental losses creep up.

Full walk-through: how to choose the right fiber optic attenuator.

 

 

Fixed vs variable

Fixed attenuators carry a preset value and you install them once — ideal for most production links. Variable optical attenuators are adjustable and indispensable for test and measurement, but cost more and need periodic calibration checks.

Type Best for Advantages Typical applications
Fixed attenuator Stable, permanent links Compact, low cost, set-and-forget FTTH, CATV, telecom, receiver protection
Variable / tunable Adjustable test setups Tunable range, fine resolution Lab testing, BER testing, margin simulation
Male-to-female (plug-in) Direct port connection Plugs into a connector or adapter Transceiver ports, patch panels
Female-to-female (adapter) Adapter-style mounting Works like an attenuating coupler ODF, fiber distribution frames
Inline (patch-cord) Built into a cable assembly Flexible, no extra mating point Testing, temporary deployment

FOCC's standard catalog focuses on fixed attenuators; tunable and inline types are made to order. 

 

UPC or APC — which polish do I need?

 

UPC · Most telecom & datacom

Flat, ultra-physical-contact end face. The default for digital telecom and data links. Pairs with the blue connectors you already have in the rack.

 

Return loss ≥ 55 dB · up to ≥ 65 dB (adapter type)

APC · Analog video, CATV & RFoG

8° angled end face. Required wherever return loss must be better than 60 dB, including analog/CATV and RF-over-glass systems.

 

Return loss ≥ 60 dB · 8° angled ferrule

Never mate APC to UPC. The angle mismatch causes high loss and reflection. Unsure on fiber type? See single-mode vs multimode fiber.

 

Fiber optic attenuator applications

 

Receiver overload protection

On short or high-power single-mode links, a fixed attenuator brings received power back inside the transceiver's input range and prevents saturation.

CWDM & DWDM power balancing

Equalize channel power across the CWDM/DWDM mux — commonly paired with our DWDM and CWDM modules.

FTTH & PON networks

Match power at the OLT, ODN and ONT, and during commissioning of PON links built around our PLC splitters.

CATV optical networks

In analog and digital video transmission, APC attenuators control receiver input power where high return loss is essential.

Test equipment calibration

Add calibrated loss for power-meter and light-source calibration, BER testing and link-margin work — pairs with our fiber tool kits.

Data center & telecom links

Manage optical power across dense cable assemblies between switches, transceivers, panels and ODFs.

 

Quality & testing

Every FOCC attenuator uses metal-ion doped attenuating fiber rather than air-gap reduction, giving a flat, wavelength-independent response and high power endurance. Our flanged adapter attenuators ship with a test report on every unit, so you can verify optical performance on arrival — and a per-unit report is available for any model on request.

Attenuation-accuracy test

Insertion-loss and return-loss test

End-face inspection

Interchangeability test

Mechanical durability test

Temperature and humidity reliability test

RoHS-compliant materials (optional)

Custom labeling and packaging for bulk orders

 

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Custom fiber optic attenuator-OEM & bulk

As a manufacturer, FOCC supports full customization for OEM and project orders. A female-to-female attenuator behaves like a standard fiber optic adapter but adds a precise, calibrated loss instead of minimizing it — useful when you need attenuation at an existing adapter position. Connector and hybrid options draw on our full connector and adapter ranges.

Request a custom quote

 

Fiber optic attenuator FAQ

Q: What is a fiber optic attenuator used for?

A: It reduces optical power by a set amount so the signal stays within a receiver's working range. That protects receivers from overload, balances channel power in WDM systems, and lets engineers test power margins.

Q: How do I know what dB attenuator I need?

A: Measure the received power with an optical power meter and subtract your receiver's target input. If you read −5 dBm and the receiver works best at −15 dBm, you need about 10 dB. When designing a new link, use Tx output − link loss − target Rx input, and add a few dB of safety margin.

Q: What is the difference between fixed and variable attenuators?

A: A fixed attenuator has one preset value (1–25 dB) and is set-and-forget — ideal for production links. A variable attenuator is adjustable across a range and is used for lab work, testing and receiver characterization.

Q: Should I choose a UPC or APC fiber attenuator?

A: Use UPC for most telecom and datacom links (return loss ≥55 dB). Use APC for analog video, CATV/RFoG, or wherever return loss better than 60 dB is required. Never mate APC to UPC.

Q: Can I use it with LC, SC, FC or ST connectors?

A: Yes. FOCC offers attenuators in LC, SC, FC, ST and MU. Choose the connector and polish that match your equipment so no extra adapter is needed.

Q: Are they mainly for single-mode or multimode fiber?

A: Most are used on single-mode links (telecom, FTTH, WDM). Multimode versions for 850 nm are available when your link requires them.

Q: Where should a fiber optic attenuator be installed?

A: Male-to-female plug-in attenuators go directly on a transceiver port, adapter or the end of a patch cord. Female-to-female adapter types mount in an ODF or distribution frame between two patch cords.

Q: Can FOCC customize value, connector or packaging?

A: Yes. We customize dB value, connector, polish, fiber mode, structure, labeling and packaging, and can provide test reports for bulk orders.

 

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Get fiber attenuators built to your spec

A leading China manufacturer of fiber optic attenuators, FOCC delivers consistent, stable attenuation for WDM, FTTH, CATV, telecom and data-center links — at a competitive price, with customized service and quotation on request.

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Focc Technology is one of the leading China manufacturers and suppliers providing you with fiber optic attenuator. Our factory has applied the most advanced equipment and technology to better serve you. Please be free to buy our fiber optic attenuator products with competitive price. The customized service and the quotation consultation are available.

, Attenuators , Fiber Optical Attenuator , Fiber Attenuators
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