Thorlabs' Optical Spectrum Analyzers (OSAs) perform highly accurate spectral measurements. Compatible with fiber-coupled and free-space light sources, these benchtop instruments suit a wide variety of applications, such as analyzing the spectrum of a telecom signal, resolving the Fabry-Perot modes of a gain chip, and identifying gas absorption lines. We offer two instrument types: the general-purpose OSA20xC instruments, which have a high update rate and moderate resolution, and the high-performance Redstone® OSA30x instruments, which have a high dynamic range and high resolution.

  • Dual-Function Broadband Spectrometer and Wavelength Meter
  • 1.9 GHz or 7.5 GHz Resolution Models
  • Seven Models Available for Wavelengths from 250 nm to 12.0 µm
  • FC/PC Fiber Connector and Free-Space Optical Inputs

Features

  • General-Purpose (OSA20xC) and High-Performance (Redstone® OSA30x) Instruments Available
  • Spectrometer Mode Resolution
  • OSA20xC: 7.5 GHz (0.25 cm-1)
  • OSA30x: 1.9 GHz (0.063 cm-1)
  • Wavelength Meter Mode Resolution: 0.1 ppm (Only for <10 GHz Linewidth Sources)
  • Spectrum Obtained Using Michelson Interferometer and Fourier Transform
  • Free-Space (with Cage Compatibility) and FC/PC Fiber-Coupled Inputs
  • Operated by Included Windows® Laptop with Pre-Installed Software
  • Straightforward, Intuitive, and Responsive Interface
  • Real-Time Math Operations and Statistical Analysis

Our optical spectrum analyzers acquire the spectrum via Fourier transform, using a scanning Michelson interferometer. This approach enables a high-precision Wavelength Meter mode with seven significant figures and ±1 part-per-million (ppm) spectral precision, allows robust statistical analysis of the acquired spectra, and provides broadband spectral measurements with every scan. A frequency-stabilized 632.9918 nm HeNe alignment laser is included in each OSA20xC unit, which is used to ensure a spectral accuracy of ±2 ppm. Each Redstone OSA includes a frequency-locked 1532.8323 nm reference laser, resulting in a spectral accuracy down to ±0.2 ppm.

Thorlabs' OSA20xC spectrum analyzers are optimized to cover five different spectral ranges with a spectral resolution of 7.5 GHz (0.25 cm-1) and a 30 dB optical rejection ratio. Designed for applications that require higher optical resolutions or sensitivities, the Redstone OSAs feature two detectors, which allow for measurements over a wide wavelength range with a 1.9 GHz (0.063 cm-1) spectral resolution, as well as a noise floor with a 40 dB optical rejection ratio. For additional details on the interferometer design, please see the Design tab.

These instruments are designed to measure CW light sources. They also work in some applications where a pulsed light source is used; details may be found on the Pulsed Sources tab. Similarly, our OSA instruments are not designed for applications where it is necessary to recover small signals, including fluorescence detection and Raman spectroscopy. If your application would benefit from increased detection sensitivity, please refer to the Custom OSAs tab for some of our capabilities.

Optical Inputs
All of Thorlabs' OSAs accept FC/PC-terminated fiber patch cables and collimated free-space beams up to Ø6 mm (OSA20xC) or Ø10 mm (Redstone OSA30x). Details on compatibility are in the Specs and Free-Space Coupling tabs. For wavelengths from 2 µm to 5.5 µm, we offer fluoride single mode and fluoride multimode fiber patch cables. Optical Spectrum Analyzers with other fiber input receptacles are available by contacting Tech Support.

Software
Each Optical Spectrum Analyzer includes a Windows® laptop with our OSA software suite pre-installed. This software includes built-in tools for simple and complex analysis, controls for adjusting sensitivity and resolution, a wavelength meter tool for narrowband sources, and a coherence length tool for broadband sources. Also available are apodization functions, which are used to account for the finite path length over which the interferogram is measured. This software also includes built-in support for the HITRAN reference database for spectroscopic analysis. For additional details on software capabilities, please see the Software tab.

Application Note

Due to its broad wavelength responsivity, the OSA207C's noise floor is higher than that of our other Optical Spectrum Analyzers, which achieve lower noise floors at the expense of having narrower wavelength ranges. This OSA will easily detect lasers and other narrowband sources, but many broadband sources will not have sufficient power spectral density to be detected. This plot compares the OSA207C's noise floor in Power Density mode to an ideal 1900 K black body and Thorlabs' SLS202La Stabilized Broadband Light Source (which was measured with an OSA205C).

Fourier Transform Optical Spectrum Analyzers, 7.5 GHz Resolution

Five Models Optimized for Different Spectral Ranges

  • OSA201C: 350 - 1100 nm
  • OSA202C: 600 - 1700 nm
  • OSA203C: 1.0 - 2.6 µm (10 000 - 3846 cm-1)
  • OSA205C: 1.0 - 5.6 µm (10 000 - 1786 cm-1)
  • OSA207C: 1.0 - 12.0 µm (10 000 - 833 cm-1)
  • Two Optical Input Ports
  • FC/PC Fiber-Coupled Input
  • Free-Space Input with Four 4-40 Taps for 30 mm Cage System Compatibility
  • Built-In Hose Connections for Optional Purging
  • Includes Windows® Laptop and Items Shown in Shipping List Tab 
  • Demo Units Available by Contacting Tech Support

Thorlabs' OSAs measure the optical power of both narrowband and broadband sources as a function of wavelength. The maximum spectral resolution of 7.5 GHz (0.25 cm-1) is set by the maximum optical path length difference of ±4 cm, as explained in the Design tab, while the high spectral accuracy of ±2 ppm (parts per million) is ensured by simultaneously measuring the interferogram of a stabilized 632.9918 nm HeNe laser. For sources with linewidth <10 GHz, the Wavelength Meter mode provides center wavelength measurements with 0.1 ppm resolution and ±1 ppm accuracy.

Fourier Transform Optical Spectrum Analyzers, 1.9 GHz Resolution

Multi-Detector Configuration for Broad Operation Range

  • OSA302: 250 nm - 2.5 µm (40 000 - 4000 cm-1)
  • OSA305: 1.0 - 5.6 µm (10 000 - 1786 cm-1)
  • Four Resolution Settings and Three Sensitivity Levels 
  • Front Panel Access to Frequency-Locked Laser for Wavelength Calibration
  • Two Optical Input Ports
  • FC/PC Fiber-Coupled Input
  • Free-Space Input with Four 4-40 Taps for 60 mm Cage System Compatibility
  • Trigger Input for External Synchronization
  • Built-In Hose Connections for Optional Purging
  • Includes Windows® Laptop and Items Shown in Shipping List Tab 
  • Demo Units Available by Contacting Tech Support

Thorlabs' Redstone® OSA302 and OSA305 Optical Spectrum Analyzers (OSA) measure the optical power of both narrowband and broadband sources as a function of wavelength with higher resolution and a lower noise floor compared to the OSAs sold above. The maximum spectral resolution of 1.9 GHz (0.063 cm-1) is set by the maximum optical path length difference of 16 cm, as explained in the Design tab, while the high spectral accuracy reaching down to ±0.2 ppm (parts per million) is ensured by simultaneously measuring the interferogram of a frequency-locked 1532.8323 nm alignment laser. For sources with linewidths <10 GHz, the Wavelength Meter mode provides center wavelength measurements with 0.1 ppm resolution and ±0.5 ppm accuracy.

To meet the needs of your specific application, customization options are available for the Redstone OSAs; please contact Tech Support for assistance. Common specials for this device include alternative input receptacles, small adjustments to the wavelength range, extra test protocols, and shipping without a laptop.

Resolution and Sensitivity
These high-performance OSAs offer four resolution settings that can resolve spectral features 4.0, 1.0, 0.25, or 0.063 cm-1 apart. Three sensitivity levels are also available, which control the acquisition speed and available gain levels. For detailed specifications on the acquisition update frequency for each sensitivity and resolution setting, please see the Specs tab. 

Calibration Laser
For the Redstone OSAs, the internal frequency-locked calibration laser is accessible through the FC/APC fiber output located above the power switch on the front panel. This can be used for wavelength calibration by connecting the front-panel output to the FC/PC fiber input using the included single mode patch cable. During calibration, the software compares the measured wavelength to the reference and performs a calibration if necessary.

Interferogram Averaging
An integrated internal broadband reference source allows the Redstone OSAs to accurately determine the location of zero path difference (ZPD) between the two optical branches. The ZPD can be used to average interferograms, which reduces the signal-to-noise ratio. The beam profile overlap between the two branches is optimized using piezoelectric actuators.

For further details, please click here

Quick Comparison
Item # OSA20xC Redstone® OSA30x
Spectral Resolution 7.5 GHz (0.25 cm-1) 1.9 GHz (0.063 cm-1)
Spectral Accuracy ±2 ppm ±0.2 ppm
Wavelength Meter Accuracy ±1 ppm ±0.5 ppm
Power Level Accuracy ±1 dB ±0.4 dB
Optical Rejection Ratio 30 dB 40 dB
Polarization Dependence ±1 dB ±0.2 dB (OSA302)
±0.1 dB (OSA305)
Free-Space Input
(Collimated Beams)
≤Ø6 mm ≤Ø10 mm
Input Fiber Compatibility FC/PC Connectors as Standard
Dimensions 320.3 mm x 149.2 mm x 474.7 mm
(12.61" x 5.88" x 18.69")
541.0 mm x 224.1 mm x 532.6 mm
(21.30" x 8.82" x 20.97")
Weight 20 lbs (10 kg) 58.4 lbs (26.5 kg)
  • See the Specs tab for details on all available models.
  • Absolute Power mode is recommended for narrowband sources, while Power Density mode is recommended for broadband sources.
  • This is the resolution in spectrometer mode, and details for this calculation can be found on the Design tab.