Femtosecond pulse operation of a Tm,Ho-codoped crystalline laser near 2 μm

Abstract

We demonstrate, for the first time to our knowledge, femtosecond-regime mode locking of a Tm,Ho-codoped crystalline laser operating in the 2 microm spectral region. Transform-limited 570 fs pulses were generated at 2055 nm by a Tm,Ho:KY(WO(4))(2) laser that produced an average output power of 130 mW at a pulse repetition frequency of 118 MHz. Mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror.

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

“…It is well known that OHcontaining liquids are prone to bleaching effects on nanosecond time scales [10] that could initiate undesirable Q-switching instabilities in a solid-state laser system and prevent broadband mode locking. Recently, using a Tm-Ho codoped KYðWO 4 Þ 2 gain medium, we demonstrated the generation of 570 fs pulses in a soliton modelocking regime at 2055 nm, with an average output power of 130 mW [11]. However, the sharpness of the optical absorption and emission bands of Ho 3þ (4f 10 electronic configuration), as in most trivalent lanthanides with 4f N (N<11) electronic configurations, places limits on the pulse durations that can be attained.…”

“…A Ti:sapphire laser producing 1:1 W of output power at 795 nm was used as the pump source and its beam (π polarized) was focused into the gain medium via a 63 mm focal length lens to a spot radius of 29 μm (1=e 2 intensity) measured in air at the location of the input facet of the gain crystal. The SESAM structure used for the initiation and stabilization of passive mode locking was similar to that described in [11], with the difference that ion implantation with 2 MeV N þ ions at a dosage level of 2 × 10 11 ions=cm 2 was applied to reduce the absorber recovery time. This ion-implanted SESAM was characterized to have about 1% of insertion losses compared to 0.8% for the as-grown structure at 2060 nm.…”

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].…”

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.…”