CEO stabilized frequency comb from a 1-μm Kerr-lens mode-locked bulk Yb:CYA laser

Abstract

We report the first Kerr-lens mode-locked (KLM) bulk frequency comb in the 1-μm spectral regime. The fundamental KLM Yb:CYA laser is pumped by a low-noise, high-bright 976-nm fiber laser and typically provides 250-mW output power and 57-fs pulse duration. Only 58-mW output pulses were launched into a 1.3-m photonic crystal fiber (PCF) for one octave-spanning supercontinuum generation. Using a simplified collinear f-2f interferometer, the free-running carrier-envelope offset (CEO) frequency was measured to be 42-dB signal-to-noise ratio (SNR) for a 100-kHz resolution and 9.6-kHz full width at half maximum (FWHM) under a 100-Hz resolution. A long-term CEO control at 23 MHz was ultimately realized by feeding the phase error signal to the pump power of the oscillator. The integrated phase noise (IPN) of the locked CEO was measured to be 316 mrad with an integrated range from 1 Hz to 10 MHz. The standard deviation and Allan deviation for more than 4-hour recording are 1.6 mHz and 5.6 × 10(-18) (for 1-s gate time), respectively. This is, to the best of our knowledge, the best stability achieved among the 1-μm solid-state frequency combs.

Carrier-envelope offset frequency stabilization of a thin-disk laser oscillator operating in the strongly self-phase modulation broadened regime

“…In the bulk geometry, f CEO -stabilized Yb:CALGO oscillators delivered pulses as short as 64 fs at an average power level of 2 W [12,13]. A shorter pulse duration of 57 fs has been achieved from a f CEO -stabilized Yb:CYA oscillator but at a lower average power of 250 mW [14]. In the thin-disk geometry, f CEO -stabilization has been realized with an Yb:CALGO thin-disk laser (TDL) oscillator delivering 77 fs pulses at 2.1 W average power [15,16].…”

“…Overview of f CEO -stabilized Yb-DPSSL oscillators delivering sub-100-fs pulses without external pulse compression. So far, they have relied exclusively on broadband gain materials (bulk [12][13][14], thin-disk laser (TDL) [15,16]). Our Yb:Lu 2 O 3 TDL oscillator operates in the strongly self-phase modulation (SPM) broadened regime and is highlighted with a green star symbol.…”

Diode-pumped power scalable Kerr-lens mode-locked Yb:CYA laser

“…One usually employs a tight focusing cavity to enhance the Kerr-lens effect for generating ultrashort pulses, which is incompatible with the large pump spot of a multimode LD, resulting in not only bad mode matching as well as low efficiency but also multimode operation. An effective way we propose here is to separate the gain medium and Kerr medium in a double confocal cavity, which has been confirmed in a Kerr-lens mode-locked Yb:YAG thin disk laser [21]. By doing so, we can release the restrain imposed on the laser crystal, which usually acts in the double role of gain medium and Kerr medium.…”

“…On the other hand, employing a single-mode fiber laser, which has high brightness as well as excellent linear-polarization property, is an alternative way to cope with this issue. Yu et al implemented a fiber-laser-pumped KLM Yb:CYA laser providing 250 mW output power and 57 fs pulse duration, which was used to develop an optical frequency comb [21]. However, the singlemode fiber laser is costlier and has lower power than the commonly used multimode LDs.…”

Sub-40-fs high-power Yb:CALYO laser pumped by single-mode fiber laser

“…demonstrated a single-mode fiber-laser-pumped pure KLM Yb:CALGO oscillator, delivering 40-fs pulses with 1.1-W average power [3] . However, preliminary results of only 250-mW output power and 57-fs pulse duration were generated from a single-mode fiber-laser-pumped Yb:CALYO laser [20] , which is far away from the expectation of generating much higher output power with shorter pulse duration considering the good optical and thermal properties of the Yb:CALYO crystal.…”