Variable Fiber Optical Attenuators, Polarization Maintaining

Polarization-Maintaining, Inline, Variable Fiber Optic Attenuators
Up to 50 dB Attenuation
630, 780, 1064, or 1310/1550 nm Center Wavelength

Adjustment Screw
Located on Top

VOA780PM-FC

VOA50PM-APC

FC/APC

FC/PC

Please Wait

Overview
Attenuation Data
Feedback

Schematic for Operation of a Variable Optical Attenuator

Click to Enlarge

Fiber Optic Attenuator Selection Guide
SM	Electronic VOAs for System Integration
	Digital VOAs
	Tabletop EVOAs with Power Lock
	Manually Variable Attenuators
	Fixed-Value Attenuators
MM	Fixed-Value Attenuators
MM	Manually Variable Attenuators
PM	Electronic VOAs for System Integration
PM	Manually Variable Attenuators

Features

Bi-Directional, Inline, Variable Fiber Optical Attenuators
Collimator-Based Manually Variable Attenuation
1 m Long PM Fiber Pigtail on Each Side

Thorlabs' Polarization-Maintaining Variable Optical Attenuators (PM VOAs) allow the user to manually vary the attenuation of a signal for precise power balancing in fiber circuits or evaluation of the dynamic range of measurement systems. Adjustment of the attenuation is achieved using the thumbscrew on the top of the housing.

The attenuator is comprised of an input fiber, collimating lens, blocking device, focusing lens, and output fiber. By turning the thumbscrew, the blocking device is shifted into the beam path, blocking part of the free-space beam (refer to the schematic to the right). Then, a second lens is used to couple light into the output fiber. Therefore, by turning the screw, one can manually alter the coupling efficiency until the desired attenuation is obtained.

All in-line PM VOAs have fiber pigtails with a Ø900 µm jacket and are available with 2.0 mm narrow key FC/PC- or FC/APC-connectorized fiber pigtails with the key aligned to the slow axis. For other connector styles or custom requests, please contact technical support.

Attenuation Range

Shown below is a sample attenuation curve obtained by testing the VOA780PM-APC. The device was tested with the adjustment screw in the closed position (blocking the light). The screw was then turned counterclockwise in quarter turns until the attenuation specification was met. PM VOAs with other center wavelengths exhibit similar performance. Please note: changes in turning direction may cause a small offset in attenuator position due to backlash.

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Click for Raw Data

Posted Comments:

user (posted 2024-01-22 10:31:41.587)

Hi I would like to use this at high power (1 W). Where does the input power limitation comme from, the input connectors or the optical assembly in the middle? If necessary, I can fuse the input/output fiber to my setup to avoid this limitation. Best regards François

ksosnowski (posted 2024-01-22 12:43:33.0)

Hello François, thanks for reaching out to Thorlabs. Both the connectors and the internal fiber terminations are using similar epoxies and will see similar thermal related limits due to the total power. At some point the epoxy will soften which can lead to drift of alignment, which increases the loss, and results in damage to the device. Unfortunately splicing won't get around this limit.

user (posted 2018-01-30 10:26:40.157)

Please make 980nm version. Thanks!

tcampbell (posted 2018-01-31 08:43:19.0)

Hello, thank you for contacting Thorlabs. I have posted this suggestion in our internal engineering forum. Feel free to email techsupport@thorlabs.com for help in finding a suitable solution for your application.

630 nm Polarization-Maintaining Variable Optical Attenuators: In-Line

Item #	Operating Wavelength	Attenuation Range	Attenuation Resolution	% Transmission Range	Return Loss	Max Power	Insertion Loss
VOA630PM-FC	630 ± 20 nm	3.0 - 50 dB	0.15 dB (Typical)	0.001 - 50.1%	>40 dB	300 mW	<3.0 dB
VOA630PM-APC	630 ± 20 nm	3.0 - 50 dB	0.15 dB (Typical)	0.001 - 50.1%	>40 dB	300 mW	<3.0 dB

Item #	Extinction Ratio	Operating Temperature	Storage Temperature	Fiber	Fiber Length	Housing Dimensions
VOA630PM-FC	>16 dB	0 to 70 °C	-40 to 85 °C	SM63-PS-U25D	1 m Per Side	26 mm x 18 mm x 8 mm
VOA630PM-APC	>16 dB	0 to 70 °C	-40 to 85 °C	SM63-PS-U25D	1 m Per Side	26 mm x 18 mm x 8 mm

780 nm Polarization-Maintaining Variable Optical Attenuators: In-Line

Item #	Operating Wavelength	Attenuation Range	Attenuation Resolution	% Transmission Range	Return Loss	Max Power	Insertion Loss
VOA780PM-FC	780 ± 20 nm	2.1 - 50 dB	0.15 dB (Typical)	0.001 - 61.7%	>40 dB	300 mW	<2.1 dB
VOA780PM-APC	780 ± 20 nm	2.1 - 50 dB	0.15 dB (Typical)	0.001 - 61.7%	>40 dB	300 mW	<2.1 dB

Item #	Extinction Ratio	Operating Temperature	Storage Temperature	Fiber	Fiber Length	Housing Dimensions
VOA780PM-FC	>16 dB	0 to 70 °C	-40 to 85 °C	SM85-PS-U25A	1 m Per Side	26 mm x 18 mm x 8 mm
VOA780PM-APC	>16 dB	0 to 70 °C	-40 to 85 °C	SM85-PS-U25A	1 m Per Side	26 mm x 18 mm x 8 mm

1064 nm Polarization-Maintaining Variable Optical Attenuators: In-Line

Item #	Operating Wavelength	Attenuation Range	Attenuation Resolution	% Transmission Range	Return Loss	Max Power	Insertion Loss
VOA1064PM-FC	1064 ± 20 nm	1.3 - 50 dB	0.15 dB (Typical)	0.001 - 74.1%	>45 dB	300 mW	<1.3 dB
VOA1064PM-APC	1064 ± 20 nm	1.3 - 50 dB	0.15 dB (Typical)	0.001 - 74.1%	>45 dB	300 mW	<1.3 dB

Item #	Extinction Ratio	Operating Temperature	Storage Temperature	Fiber	Fiber Length	Housing Dimensions
VOA1064PM-FC	>18 dB	0 to 70 °C	-40 to 85 °C	SM980PS-U25A	1 m Per Side	26 mm x 18 mm x 8 mm
VOA1064PM-APC	>18 dB	0 to 70 °C	-40 to 85 °C	SM980PS-U25A	1 m Per Side	26 mm x 18 mm x 8 mm

Telecom (1310/1550 nm) Polarization-Maintaining, Variable Optical Attenuators: In-Line

Item #	Operating Wavelength	Attenuation Range	Attenuation Resolution	% Transmission Range	Return Loss	Max Power	Insertion Loss
VOA50PM-FC	1310 ± 40 nm and 1550 ± 40 nm	0.9 - 50 dB	0.15 dB (Typical)	0.001 - 81.3%	50 dB	300 mW	<0.9 dB
VOA50PM-APC	1310 ± 40 nm and 1550 ± 40 nm	0.9 - 50 dB	0.15 dB (Typical)	0.001 - 81.3%	50 dB	300 mW	<0.9 dB

Item #	Extinction Ratio	Operating Temperature	Storage Temperature	Fiber	Fiber Length	Housing Dimensions
VOA50PM-FC	>18 dB	-5 to 70 °C	-40 to 85 °C	SM13-PS-U25D	1 m Per Side	26 mm x 18 mm x 8 mm
VOA50PM-APC	>18 dB	-5 to 70 °C	-40 to 85 °C	SM13-PS-U25D	1 m Per Side	26 mm x 18 mm x 8 mm