ThorLabs SA200-12A – 1250 – 1400 nm, Scanning Fabry-Perot Interferometer

The Thorlabs SA200-12A is a scanning Fabry-Perot interferometer engineered for high-resolution spectral analysis in the 1250–1400 nm infrared band. It employs a confocal cavity with high-reflectivity mirrors and a piezoelectric transducer to vary mirror separation, functioning as a tunable narrow band-pass filter for examining fine spectral structures of continuous-wave lasers. The cavity is constructed from low thermal expansion Invar® material and housed in black anodized aluminum, ensuring thermal stability across extended measurement sessions.

Technical Specifications

• Wavelength Range: 1250–1400 nm


• Free Spectral Range (FSR): 1.5 GHz


• Minimum Finesse: >200


• Resolution: 7.5 MHz


• Cavity Configuration: Confocal with Invar® construction


• Mirror Coatings: High-reflectivity (HR) on inner surfaces; anti-reflection (AR) on outer surfaces


• Maximum PZT Input Voltage: 150 V


• Flange Diameter: Ø 2"


• Total Length: 5.85"


• Apparent Beam Size: Approximately 4 mm


• Outer Housing: Black anodized aluminum

Key Features

• Lever-actuated iris diaphragms at entrance and exit for alignment and beam control


• Piezoelectric transducer enables continuous wavelength scanning with sub-GHz resolution


• Compact kinematic-mount compatible design (Ø2" flange)


• Low thermal drift from Invar® cavity material

Typical Applications

• Spectral characterization of CW lasers in the 1250–1400 nm band


• Fine-structure analysis of narrowband optical sources


• Wavelength verification and tuning of infrared laser systems

Compatibility & Integration The SA200-12A operates with the Thorlabs SA201B controller, which supplies the scanning voltage ramp (0–20 V) and enables offset and zoom control (1X to 100X resolution magnification). Signal input accepts triangle or sawtooth waveforms at 5–50 Hz frequency with 15–40 V amplitude. Spectral data is output via SMA or BNC connector to an oscilloscope or amplifier; a 5 kΩ terminator is recommended when direct detector connection is used. Mounting in a compatible kinematic mirror mount (such as Thorlabs KM200) is recommended.