Superluminescent Diodes for OCT


Superluminescent Diode (SLD) Light Source for OCT Systems

  • 1325 nm SLD, Bandwidth > 100 nm
  • Fiber-Coupled Power > 10 mW
  • SM Fiber Pigtail with FC/APC Connector
  • Integrated Optical Isolator, Thermistor, and TEC Element

SLDs are the light source of choice in Spectral Domain Optical Coherence Tomography (SD-OCT) imaging because the emission spectrum is broad and the emitted light has a short coherence length. In addition to SLD1325, Thorlabs offers an extended broadband SLD light source for OCT applications.


  • Integrated Optical Isolator for Enhanced Output Stability
  • FC/APC Terminated Fiber Pigtail Minimizes Optical Feedback
  • Integrated TEC and Thermistor for Temperature Control
  • Hermetically Sealed 14-Pin Butterfly Package


SLD Specifications

Note, these specifications are given as guidelines. The characterization sheet shipped with each SLD provides the min, max and recommended operating parameters and specifications specific to that device. All devices will exceed the bandwidth and power specifications listed below.

Item #SLD1325
Central Wavelength 1325 nm
Bandwidth (FWHM) >100 nm
Fiber-Coupled Power > 10 mW
Maximum SLD Injection Current 780 mA
Maximum Voltage 4 V
Operating Temperature Range 0 - 40 °C

Additional Specifications

Item #SLD1325
Isolation of Integrated Isolator >30 dB
Fiber Pigtail SMF-28e+
Fiber Length ~1 m
Fiber Connector FC/APC
Return Loss of FC/APC Connector >50 dB
Max Thermoelectric Cooler Current 4 A
Max Thermoelectric Cooler Voltage 4 V
Thermistor Resistancea 10 kΩ
  • Steinhart - Hart Coefficients: C1 = 1.1291x10-3,
    C2 = 2.3413x10-4, and C3 = 0.8767x10-7

As with most active semiconductor devices, standard anti-static handling procedures must be adhered to in order to prevent an electrical discharge that could destroy the device.

When the limits on current, temperature, and output power are adhered to, the lifetime of the SLD1325 will exceed 5000 hours. We strongly recommend adherence to the operating conditions marked on each package. While optimal performance is achieved by utilizing the recommended settings, we recognize users can adjust the spectral characteristics of the SLD by deviating from these recommended settings. For instance, operating at lower temperatures will cause a shift of the central wavelength to shorter wavelengths. It is imperative, however, that as the temperature is reduced, the injection current is also reduced so as not to exceed the recommended output power as noted on the package.

Operation and Warranty

The SLD should be operated in a constant current constant temperature mode, which is relatively simple with the proper SLD mount and drivers. Thorlabs recommends the following equipment for use with the SLD1325:

  • LM14S2 – Butterfly Laser Diode Mount (see SLD Mount tab)
  • ITC4001 – Combination Laser Diode and TEC Controller (see SLD Driver tab)

When purchased alone, the SLD1325 comes with a standard 1 year warranty. If purchased with the LM14S2 Butterfly Mount and ITC4001 Combination Laser Diode and TEC Controller, Thorlabs provides a 2 year warranty for the SLD1325.



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