Femtosecond pulse generation with voltage-controlled graphene saturable absorber.

Area of Science:

• Optoelectronics
• Materials Science
• Laser Physics

Background:

• Mode-locked lasers are crucial for generating ultrashort optical pulses.
• Saturable absorbers are key components for initiating and stabilizing mode-locking.
• Graphene's unique electronic properties offer potential for novel optical device applications.

Purpose of the Study:

• To demonstrate a graphene supercapacitor as a voltage-controlled saturable absorber.
• To investigate its application in femtosecond pulse generation from a solid-state laser.
• To explore the tunable nonlinear optical response of the graphene device.

Main Methods:

• Fabrication and characterization of a graphene supercapacitor.
• Integration of the device into a multipass-cavity Cr(4+):forsterite laser.
• Utilizing pump-probe spectroscopy to analyze nonlinear optical properties.
• Operating the laser system at specific bias voltages (0.5-1V).

Main Results:

• Successful demonstration of the graphene supercapacitor as a voltage-controlled saturable absorber.
• Generation of sub-100 femtosecond (fs) pulses.
• Achieved a pulse repetition rate of 4.51 MHz.
• Observed tunable insertion loss by adjusting the applied bias voltage.

Conclusions:

• Graphene supercapacitors can effectively function as voltage-controlled saturable absorbers.
• This technology enables precise control over laser pulse characteristics.
• The findings open new avenues for ultrafast laser development and applications.