Fig. 1: All system
The femtosecond laser system consists of four different lasers, namely Millennia, Tsunami, Empower, and Spitfire, as called by the manufacturer. The technical specifications for each are listed below:
- continuous laser,
- emission at 532 nm,
- gives up to 5 W optical power.
- No active component in this laser.
- Power is supplied optically through an umbilical connected to its power supply where 40 W laser diodes are located emitting at ~800nm.
- In normal operating conditions, ~ 26 W of continuous optical power is exposed to Millennia from this umbilical where there is a Vanadate (Nd: YVO4) crystal lasing at 1064 nm in its cavity.
- The emission is frequency doubled by a temperature tuned LBO crystal resulting in radiation at 532 nm.
- In our system, Millennia is used to pump the femtosecond oscillator –Tsunami‐ with a continuous optical power of 4.5 W at 532 nm wavelength.
Fig. 2: Milennia
- mode‐locked femtosecond oscillator
- emission from 690 to 1080 nm
- pulse durations from 80 ps to 50 fs
- repetition rate of ~80 MHz
- The maximum average power that can provide is ~1W yielding energy per pulse of ~12.5 nJ/pulse and peak power of ~125 kW.
- Femtosecond operation is provided by passively mode‐locking the emission from Ti: Sapphire crystal inside its cavity which is pumped by Millennia at 532 nm wavelength.
- Tsunami is optimally operated for our system if it provides ~100 fs laser pulses with 80 MHz repetition rate at 800 nm wavelength with an average power of 800 mW or higher.
Fig. 3: Tsunami
- Q‐switched laser
- emission at 527 nm
- ~10 ns pulse duration
- 20 W of maximum average power.
- The laser emission is provided by optically pumping an Nd: YLF crystal, strongly absorbing at ~792 nm and emitting ~1053 nm, with diode lasers.
- The gain medium and pump lasers are enclosed inside the laser head and co‐located in a directly water cooled resonant cavity.
- Q‐switching is provided via acousto‐optic modulators and the infrared emission at 1053 nm was frequency doubled by an intracavity LBO crystal which is on top of an oven for tuning the temperature to correct wavelength.
- The repetition rate of the laser can be externally controlled between 500 Hz and 10 kHz.
- As far as our system is concerned this laser works optimally at 527 nm wavelength with 1 kHz repetition rate and 15 W of average power for the purpose of pumping the Spitfire amplifier.
Fig. 4: Empower
- Q‐switched, cavity dumped, Ti: Sapphire, regenerative femtosecond laser amplifier
- Operation at 800 nm wavelength,
- ~120 fs pulse duration,
- 1 KHz repetition rate.
- Regenerative amplification is provided by circulating a seed laser in the active medium until gain saturation occurs.
- Ti: Sapphire gain medium is optically pumped by Empower laser at 527 nm wavelength with 15 W of average power resulting in emission at 800 nm wavelength.
- This laser works at 800 nm wavelength with 120 fs pulse duration, 1 kHz repetition rate and 3 W of average power resulting in an energy of 3 mJ for each individual pulse.
Fig. 5: Spitfire