OP665 Optical Attenuator

OP665 Optical Attenuator

The Industry’s Fastest & Most Accurate Optical Power Meters

OP665 Optical Attenuator


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 OptoTest OP665 Optical Attenuator is an essential tool for researchers, manufacturers, and calibration labs needing a fast, precise, and repeatable means of controlling transmitted or received power in the lab or on the test bench. 

High resolution and tuning speed, low loss, and excellent wavelength flatness and repeatability ensure consistently accurate measurements and test results. 

Users can save preset attenuation values in memory for later use, simplifying test sequences and reducing operator uncertainty when calibrating optical components, determining receiver sensitivity thresholds, performing Bit Error Rate Testing (BERT), and other applications, such as channel equalization in WDM systems and signal conditioning. 

Housed in a compact and sturdy benchtop case, the OP665 makes manual adjustments quick and easy using its bright, easily readable touchscreen and intuitive user interface. Built-in Ethernet and USB communication enables test automation with minimal setup time using OptoTest software or your own custom applications. The OP665 supports up to 2 attenuator channels and is available in standard single mode 9 μm fiber as well as 50 μm or 62.5 μm multimode fiber.


Stores and Retrieves Preset Attenuation Values

Easily program preset attenuation values into memory and retrieve them for later use to speed up testing time and reduce errors.

Optional Integrated Shutter

Simplifies zeroing and referencing the optical power meter with no setup changes. Protects connected equipment from accidental exposure to excessive power levels.

High Tuning Resolution and Speed

Tuning resolution of 0.01 dB for 30 dB single-mode and multimode versions. Tuning resolution of 0.15 dB for 60 dB single-mode version. Tuning speed of 50 ms min, 1400 ms max for all versions.

Excellent Wavelength Flatness and Repeatability

Flatness of  0.1 dB max for 0 to 30 dB versions (single-mode and multimode),  0.2 dB max for 0 to 60 dB version (single-mode only). Repeatability of  0.01 dB max for 30 dB single-mode version, 0.1 dB max for 60 dB single-mode version and 30 dB multimode version.

Low Excess Loss

Typical excess loss of 0.8 dB for 30 dB single-mode and multimode versions without connectors, 0.6 dB for 60 dB single-mode version without connectors. Maximum excess loss of 1.3 dB for 30 dB single-mode and multimode versions without connectors, 1.5 dB for 60 dB single-mode version without connectors.


We proudly design & manufacture our equipment in California, United States.


Transceiver Manufacturer Testing
Channel Equalization
Bit Error Rate Testing (BERT)
Signal Conditioning

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Automate, customize, and record your tests through software.

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Can be calibrated on-site, in-house or remotely.

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OptoTest offers a three-year full warranty!

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Optical Attenuator 30dB 60dB
Range 0 to 30 dB 0 to 60 dB
Tuning Resolution 0.01 dB 0.15 dB
Tuning Speed 50 ms min, 1400ms max 50 ms min, 1400 ms max
Excess Loss1 0.8 dB Typ, 1.3 dB max 0.6 dB Typ., 1.5 dBmax
PDL32 0.1 dB 0.1 dB (<30 dB), 0.3 dB (>30dB)
Flatness ±0.1 dB max ±0.2 dB max
Available Wavelengths SM 1310/1550 1310/1550
MM (50 & 62.5μm) 850/1300 N/A
Return Loss SM 50 dB max 50 dB max
MM (50 & 62.5μm) 20 dB max N/A
Repeatability SM ±0.01 dB max ±0.1 dB max
MM (50 & 62.5μm) ±0.1 dB NA
Absolute Accuracy3 SM ±0.1 dB ±0.25 dB max
MM (50 & 62.5μm) ±0.2 dB N/A
Optical Power 300 mW 300mW
Operating Temp. 0 °C to 50 °C -20 °C to 50 °C

1: Without connectors. With connectors add 0.15 dB per connector.
2: At calibration wavelengths.
3: Measured at 1550 nm.

Mainframe Benchtop
Dimensions 8.5″ x 3.5″ x 13″
Display 4.3″ Touch Screen
Power Supply Input: 90VAC … 264VAC; 47Hz to 63Hz Output: 18V, 5As
Warm-up Time 5-15 minutes
Operating Temperature 0 °C to 50 °C
Maximum Relative Humidity* 95%
Remote Interface USB/Ethernet

* For temperatures up to 31°C, decreasing linearly to 50% relative humidity at 40°C.


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