Single-Frequency Fibre Lasers

Choose an FL-SLM-Seed model when the source will drive a separate amplifier, frequency-conversion stage or low-power experiment. The seed ranges provide 1–50 mW across 1014–1120 nm, 1–40 mW across 1525–1596 nm and 1–10 mW across 1800–2000 nm, with M² down to <1.05 and linewidth options down to <5 kHz. They use single-mode PM fibre, FC/APC connectivity and conduction cooling. Amplified FL-SLM models are more suitable when the experiment requires watts of delivered optical power, reaching 70 W at 1064 nm. This distinction affects the electrical supply, cooling, enclosure size and amount of downstream optical amplification required.

Visible and red versions generally use frequency conversion and are available with free-space or fibre-coupled output, while many infrared models can use FC/APC fibre or an optional collimator. The 507–560 nm group offers up to 3 W free-space output at 532 nm, whereas its fibre-coupled options are generally limited to 500 mW or less. Near-infrared amplified models from 1014–1120 nm provide up to 10 W at most wavelengths, with the 1064 nm high-power version extending to 70 W. The 1800–2000 nm seed range provides milliwatt-level output, while FL-1908-SLM reaches 5 W. These differences determine the required beam delivery, thermal design and downstream optics.

Select the narrowest linewidth and lowest RIN grade that the measurement bandwidth and coherence requirement justify. Seed models and amplified 1064 nm or 1550 nm versions can be specified with linewidth below 5 kHz, while many visible and red models operate below 20 kHz. Wider limits apply to particular wavelengths, including <40 kHz at 550 nm, <50 kHz at 852 nm and 1908 nm, <100 kHz at 618 nm and 1120 nm, and <200 kHz at 560 nm. RIN can reach an optional <0.03% on selected seed models or <0.05% on many amplified models. Matching these values to the detector bandwidth avoids paying for tighter performance that the measurement cannot use.

The output interface should be selected according to the required beam path, power level and sensitivity to alignment. Seed models provide single-mode PM fibre through an FC/APC connector, normally with a 1 m fibre and 0.14 NA. Selected visible and red amplified models offer both free-space and fibre-coupled output, with a typical free-space beam diameter of approximately 1 mm and 0.12 NA for the fibre interface. Infrared amplified versions can use FC/APC output or an optional collimator producing a nominal 4 ±1 mm beam. Free-space output simplifies access to bulk optics, while fibre delivery can make routing easier but introduces connector-handling and power-density limits.

The range provides temperature and PZT-based tuning, although the exact travel depends on the wavelength group. Seed models specify more than 0.5 nm of temperature tuning and more than 3 GHz of PZT tuning, while the 507–785 nm amplified groups specify more than 0.2 nm and more than 5 GHz. Infrared amplified models generally provide more than 0.4 nm of temperature tuning and more than 3 GHz of PZT travel; FL-852-SLM specifies more than 0.15 nm. PZT bandwidth is above 5 kHz where stated. For control-loop design, the PZT can handle faster corrections, while temperature tuning is better suited to wider and slower wavelength positioning.

Cooling and power arrangements depend mainly on whether the selected unit is a seed source, standard amplifier or high-power converted laser. Seed models are conduction cooled, state 12 W power dissipation and use a 12 VDC, 11.5 A input, with an optional mains supply. Standard amplified versions use 110/220 VAC and may be air or water cooled. The 3–15 W and 20–40 W 532 nm versions require water cooling, while the 1064 nm high-power model can be air cooled up to 15 W or water cooled across its full power range. All listed versions require an operating environment of 15–30°C, so enclosure ventilation and coolant capacity should be planned before installation.

Yes, provided the chosen wavelength, power, linewidth and noise grade match the transition or measurement method. Available wavelengths include 780 nm for rubidium-related work, 852 nm for caesium-related systems, visible outputs for cooling and trapping, and narrow-linewidth infrared sources for interferometry and optical pumping. Seed versions provide M² below 1.05 and polarisation ratios above 20 dB across the 1014–1596 nm bands, while most amplified models specify M² below 1.1 and polarisation above 15 dB. PZT tuning above 3 GHz or 5 GHz supports frequency positioning and stabilisation. Practical selection should also account for detector bandwidth, optical-isolator requirements, beam delivery and available cooling infrastructure.