Graphene saturable absorber for compact ultrashort pulse lasers


Rusgraphene specialists, together with colleagues from General Physics Institute of Russian Academy of Sciences, Fiber Optics Research Center of  Russian Academy of Sciences, Bauman State University, MEPhI and MIPT, used graphene as an effective saturable absorber for the development of compact ultrashort pulse lasers. The results are published in the journal Quantum Electronics [1], [2].

Laser sources of ultrashort pulses are applicable for processing materials, laser location, gas analysis, high-speed transmission of large amounts of data. They can be used as master oscillators for volume amplifiers and non-linear frequency converters.

Saturated absorbers such as Semiconductor Saturable Absorber Mirror (SESAM) semiconductor structures are traditionally used to operate lasers in passive mode locking. However, the use of graphene provides a number of significant advantages: small thickness, ultrafast (less than 5 ps) relaxation times, constant linear transmittance (~ 2.3%) in the range from UV to IR, and the possibility of applying directly to the active element or mirror of the resonator.

Saturable absorbers based on graphene and single-walled carbon tubes were used in a holmium fiber laser operating in the hybrid mode locking mode. Depending on the type of mode locking, different parameters of laser radiation were obtained: the central radiation wavelength varied from 2040 to 2085 nm, the average output radiation power was from 5 to 15 mW, and the pulse duration was from 0.5 to 1.3 ps. The pulse repetition rate was 20.5 MHz [1].

Based on a waveguide in an Nd: YAG crystal and single-layer CVD graphene manufactured by Rusgrafen, a solid-state picosecond laser with a pulse repetition rate of 9.8 GHz operating at a wavelength of 1061 and 1064 nm was created. The possibility of simultaneous two-wave generation in the mode of passive mode locking using one saturable graphene-based absorber is demonstrated. Such a laser operating mode may be of interest for the generation of terahertz radiation at a difference frequency of the wavelengths 1061.58 and 1064.18 nm (Dn = 0.44 THz) [2].


[1] Spectral and temporal dynamics of ultrashort pulses in a holmium-doped fibre amplifier original paper

[2] GHz Repetition Rate of Picosecond Pulses in a Nd:YAG Waveguide Laser original paper

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