Thorlabs' FSL1550 High-Power Erbium-Doped Ultrafast Fiber Laser is a turnkey source that offers ultra-short pulses (<40 fs) in the 1550 nm wavelength band. This laser provides high peak power (estimated >60 kW) with >500 mW average power at the fundamental oscillator repetition rate of 100 MHz. The combination of a short pulse width and a high peak power make the FSL1550 ultrafast fiber laser an ideal source for nonlinear optics applications such as supercontinuum generation and terahertz generation, while the high repetition rate makes it compatible with Fourier-Transform Infrared (FTIR) spectrometers. This laser features an all-PM-fiber design with no free-space or moving parts to maximize environmental stability.


  • Ultrashort Pulses: <40 fs (Typical)
  • 1560 nm ± 30 nm Center Wavelength
  • >500 mW Average Output Power, >5 nJ Pulse Energy, and 100 MHz Repetition Rate
  • Free-Space, Collimated Output Beam (2 mm Nominal Beam Diameter)
  • Air-Cooled Housing with Integrated Controller


  • Supercontinuum Generation
  • Terahertz Generation
  • Ultrafast Spectroscopy
  • Multiphoton Imaging

The ultra-short pulse width of the laser is achieved through nonlinear pulse compression and by managing the effects of dispersion and nonlinearity in the fiber. Due to this design, the output pulse width is a function of the output power level. This ultrafast fiber laser is designed for optimal pulse compression conditions (FWHM <40 fs) at a power level greater than 500 mW. All systems are shipped with a data sheet showing the measured pulse intensity profile at the optimal power level, as well as a few lower power set-points. A typical intensity profile of the output pulse as retrieved by frequency-resolved optical gating (FROG) measurement and a typical optical spectrum of the output pulses can be found on the Graphs tab.

The controller of the FSL1550 ultrafast fiber laser is fully integrated with the laser head inside a benchtop enclosure, making the source compact and easy to use. The laser platform includes standard Ø1" pedestal legs, which can be secured to the optical table using the four included CF175 clamping forks for added beam stability. The output of the laser is a collimated beam with a nominal diameter of 2 mm, which is accessible through a front panel aperture that sits 3.00" (76.2 mm) above the optical table. An electrically-controlled shutter is used to control access to the laser emission. The housing also features a vibration isolation mechanism to reduce the impact of the cooling fan vibration on the output beam stability, as well as on the optical table.

User control functions, such as laser enable, shutter control, and output power adjustment, are accessible through an intuitive front panel. Green indicator LEDs are included to show when the shutter is open and the laser emission turned on; note that the laser emission LED will blink rapidly for three seconds while the laser turns on. This ultrafast fiber laser also features a front-panel display (shown to the right) that shows the pump level and status indicators of the system, including the temperature and emission status. For additional safety, the user may connect an interlock circuit to the BNC connector on the rear panel. See the Front & Back Panels tab for more details.

This ultrafast fiber laser uses a universal power supply allowing operation over 100 - 240 VAC without the need to select the line voltage. A region-specific power cord is included.

Thorlabs also offers additional fiber lasers, including the FSL1950F 2 µm Femtosecond Fiber Laser and the SC4500 Mid-IR Supercontinuum Source. The 2 µm femtosecond laser produces ultrashort pulses (<80 fs) with a >500 mW average output power, while the supercontinuum source emits over a wavelength range from approximately 1.3 μm to 4.5 μm& with >300 mW of average output power in a collimated beam. See their respective web presentations for full performance details.

Specifications FSL1550
Center Wavelength 1560 nm ± 30 nm
Pulse Width (FWHM) <40 fs (Typical)
<50 fs (Max)
Peak Powera >60 kW
Ouput Powerb >500 mW (Average)
Repetition Rate 100 MHz (Nominal)
Pulse Energy >5 nJ
Polarization Extinction Ratio >15 dB
Beam Size Ø2 mm (Nominal)
Output Power Stabilityc <0.4% / °C
Dimensions (L x W x H) 403.6 mm x 432.0 mm x 147.3 mm
(15.89" x 17.01" x 5.80")

Lasers & other Sources