Development of diode-pumped high average power continuous-wave and ultrashort pulse Yb:KGW lasers for nonlinear microscopy

Abstract

We report on the development of diode-pumped high power continuous-wave (CW) and ultrashort pulse Yb:KGW lasers for applications in nonlinear multimodal microscopy. In the CW regime we generated 5W of average output power from a simple three-mirror cavity, with 22% of optical-to-optical conversion efficiency. The CW laser was used as a platform for development of a high power mode-locked oscillator. We achieved 2.3W of average output power in the mode-locked regime with ~210 fs duration pulses centered around 1047 nm at a repetition rate of 97 MHz. This corresponds to 24 nJ of energy per pulse and 114 kW of peak power. The demonstrated laser will be used in second-and third-harmonic generation microscopy of biological samples.

High power Nd:YVO-KGW conical refraction laser

“…The CR crystal was an 18 mm-long anti-reflection coated KGW crystal which was cut along its optical axis. KGW crystals are wellknown for the CR effect [38][39][40][41][42], have good optical quality [11] and are typically used as host for Nd-and Yb-ion lasers [43][44][45][46][47][48][49][50][51][52][53]. A photograph of the developed laser is shown in Fig.…”

Diode-pumped Yb:CALGO laser with conical refraction output

“…Also, since the quantum defect (the difference between the pump and laser photon energies) is low this makes Yb-ion crystals attractive for high power laser operation [24][25][26][27][28][29][30][31]. Considering these important characteristics, Yb-ion lasers are becoming reliable in applications such as micromachining [32], optical communication [33], multiphoton microscopy [34][35][36][37][38][39] and nonlinear optics [40][41][42][43]. There are different types of Yb laser crystals available but Yb:CALGO is the most popular one because of its high thermal conductivity (6.5 W/m/K) with a 50 nm broad emission spectrum which makes it suitable for high power laser operation [44][45][46][47][48][49][50][51][52][53][54][55].…”

Efficient continuous-wave self-Raman Yb:KGW laser with a shift of 89 cm^−1

“…The emission spectrum of the Yb:KGW crystal is shown in Fig. 1(a) which is re-plotted from [15]. Due to the quasi-three-level nature of the Yb:KGW crystal, the absorption and emission spectra are overlapping and the laser action can only be observed in the wavelength range from 1025 nm to 1090 nm [15] when the reabsorption loss is taken into consideration.…”

“…1(a) which is re-plotted from [15]. Due to the quasi-three-level nature of the Yb:KGW crystal, the absorption and emission spectra are overlapping and the laser action can only be observed in the wavelength range from 1025 nm to 1090 nm [15] when the reabsorption loss is taken into consideration. The Raman spectrum of KGW as the Raman material measured by Kasprowicz et al [16] is re-plotted in Fig.…”