Femtosecond (191 fs) NaY(WO_4)_2 Tm,Ho-codoped laser at 2060 nm

Abstract

We report, for the first time to our knowledge, femtosecond-pulse operation of a Tm; Ho:NaYðWO 4 Þ 2 laser at around 2060 nm. Transform-limited 191 fs pulses are produced with an average output power of 82 mW at a 144 MHz pulse repetition frequency. Maximum output power of up to 155 mW is generated with a corresponding pulse duration of 258 fs. An ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror is used for passive mode-locking maintenance.

121 W passively mode-locked Tm:LuAG laser

“…The damage threshold of saturable absorbers is considered as one of the power limiting factors. To date, various saturable absorbers have been successfully utilized in realizing passively mode-locked Tm-doped bulk lasers, such as semiconductor saturable absorber mirrors (SESAMs) [1,[7][8][9][10][11], single-walled carbon nanotubes (SWCNTs) [12,13] and graphene [14][15][16]. Since the SWCNT and graphene could be easily damaged under high pump level [13,14], the obtained 2 μm mode-locking laser powers by using SWCNT saturable absorbers ranged from 35 mW [12] to 240 mW [13], while the achieved output powers from graphene based mode-locked 2 μm lasers were mainly constrained around 100 mW [14][15][16].…”

Broadly tunable femtosecond mode-locking in a Tm:KYW laser near 2 μm

“…By codoping with Tm and Ho, efficient lasers can be configured to provide emission in a slightly longer wavelength range (~2000-2150 nm) where weaker water absorption bands occur, thereby enhancing the prospects for broadband and stable mode-locking. Recently, we have reported the generation of 570-fs pulses from a passively mode-locked Tm,Ho:KY(WO 4 ) 2 laser [13] and pulses as short as 191 fs were produced from Tm,Ho:NaY(WO 4 ) 2 [14], both operating around 2060 nm. It must be recognized though, that Tm-Ho codoped materials can suffer from the presence of increased up-conversion processes [15] compared to single Tmdoping and this in turn can lead to additional thermal loading inside the gain medium, resulting in reduced laser efficiency and limited output powers during continuous wave operation at room temperature.…”

Passively mode locked femtosecond Tm:Sc_2O_3 laser at 21 μm

“…These include a Tm-doped fiber laser that was passively mode locked using an additive-pulse mode-locking technique to produce pulses with energies of up to 4 nJ (167 mW of average power) that were compressed externally to a duration of 173 fs. However, this involved a rather complex configuration that required a combination of fiber and free-space optics as well as an external-cavity pulse compressor.Recently, we have demonstrated the efficient generation of femtosecond pulses directly from Tm-doped and Tm,Ho codoped solid-state crystalline lasers by using a semiconductor saturable absorber mirror (SESAM) for passive mode locking [10][11][12]. In particular, 191 fs pulses were produced from Tm, Ho:NaYWO 4 2 around 2060 nm and a Tm:KYWO 4 2 laser generated 386 fs pulses with an average power of 235 mW at 2029 nm.…”

“…Recently, we have demonstrated the efficient generation of femtosecond pulses directly from Tm-doped and Tm,Ho codoped solid-state crystalline lasers by using a semiconductor saturable absorber mirror (SESAM) for passive mode locking [10][11][12]. In particular, 191 fs pulses were produced from Tm, Ho:NaYWO 4 2 around 2060 nm and a Tm:KYWO 4 2 laser generated 386 fs pulses with an average power of 235 mW at 2029 nm.…”

“…The resonator was designed to operate in the middle of stability zone II to ensure a second mode waist on the saturable absorber element. The SESAM used for passive mode locking initiation and stabilization is based on an ionimplanted InGaAsSb quantum-well structure and characterized by an initial reflection of 99.5%-98.1% in the 2-2.1 μm range [11]. It was mounted on a copper heat sink to ensure efficient heat removal during prolonged laser operation.…”