Watt-level and sub-100-fs self-starting mode-locked 2.4-µm Cr:ZnS oscillator enabled by GaSb-SESAMs


Barh A., Heidrich J., Alaydin B. Ö., Gaulke M., Golling M., Phillips C., ...Daha Fazla

Optics Express, cilt.29, sa.4, ss.5934-5946, 2021 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 29 Sayı: 4
  • Basım Tarihi: 2021
  • Doi Numarası: 10.1364/oe.416894
  • Dergi Adı: Optics Express
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, EMBASE, MEDLINE, Directory of Open Access Journals
  • Sayfa Sayıları: ss.5934-5946
  • Sivas Cumhuriyet Üniversitesi Adresli: Evet

Özet

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing AgreementFemtosecond lasers with high peak power at wavelengths above 2 µm are of high interest for generating mid-infrared (mid-IR) broadband coherent light for spectroscopic applications. Cr2+-doped ZnS/ZnSe solid-state lasers are uniquely suited since they provide an ultra-broad bandwidth in combination with watt-level average power. To date, the semiconductor saturable absorber mirror (SESAM) mode-locked Cr:ZnS(e) lasers have been severely limited in power due to the lack of suitable 2.4-µm SESAMs. For the first time, we develop novel high-performance 2.4-µm type-I and type-II SESAMs, and thereby obtain state-of-the-art mode-locking performance. The type-I InGaSb/GaSb SESAM demonstrates a low non-saturable loss (0.8%) and an ultrafast recovery time (1.9 ps). By incorporating this SESAM in a 250-MHz Cr:ZnS laser cavity, we demonstrate fundamental mode-locking at 2.37 µm with 0.8 W average power and 79-fs pulse duration. This corresponds to a peak power of 39 kW, which is the highest so far for any saturable absorber mode-locked Cr:ZnS(e) oscillator. In the same laser cavity, we could also generate 120-fs pulses at a record high average power of 1 W. A comparable laser performance is achieved using type-II InAs/GaSb SESAM as well. These results pave the way towards a new class of high-power femtosecond SESAM mode-locked oscillators operating directly above 2-µm wavelength.