Misalignment-free, Kerr-lens-modelocked Yb:Y₂O₃ 2.2-GHz oscillator, amplified by a semiconductor optical amplifier

Current laser systems often require complex alignment and suffer from sensitivity to environmental changes. Prior research has shown that Kerr-lens modelocking can produce ultrafast pulses, but maintaining stability remains a challenge. No prior work had resolved the issue of misalignment in high-repetition-rate oscillators. This gap motivated the development of a misalignment-free design. The need for compact and robust laser sources is well established in industrial and scientific applications. Existing systems often require manual adjustments to maintain performance. Environmental factors like temperature can disrupt pulse characteristics. A self-starting, stable laser would address these limitations.

The goal was to create a laser system that eliminates the need for realignments during operation. The researchers aimed to produce ultrafast pulses with high repetition rates. They focused on a design that would remain stable under varying conditions. The motivation was to simplify laser operation for practical use. They also wanted to demonstrate amplification without compromising pulse quality. The study tested a fully bonded cavity to achieve this. They evaluated the system's noise and tuning range. The design needed to support both modelocking and amplification.

The team used a diode-pumped Yb:Y2O3 ceramic oscillator. The cavity was fully bonded to prevent misalignment. They implemented Kerr-lens modelocking for pulse generation. The system operated in a ring configuration for stability. A semiconductor optical amplifier was used for amplification. They measured output power and pulse characteristics. Temperature changes were applied to test tuning range. Noise levels were analyzed over a 1 Hz to 1 MHz range.

The oscillator produced 190-fs pulses at 2.185 GHz repetition rate. Output power ranged from 14 to 30 mW with pump powers of 380 to 670 mW. The system achieved self-starting modelocking from both cavity outputs. Relative intensity noise was measured at 0.025%. Pulse repetition rate tuning reached 120 kHz with 2°C temperature change. Amplification increased average power to 69 mW. Pulse energy rose from 2.5 pJ to 32 pJ. Peak power increased from 12 W to 71 W.

The authors demonstrated a misalignment-free laser with stable modelocking. The fully bonded design enabled turnkey operation. The system showed low noise and high tuning flexibility. Amplification with a semiconductor optical amplifier was effective. The temperature sensitivity allowed for controlled repetition rate changes. The results suggest practical use in applications requiring stability. The design reduces the need for manual adjustments. The study supports the feasibility of compact ultrafast laser systems.