Switching, amplifying, and chirping diode lasers with current pulses for high bandwidth quantum technologies.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Technology

Background:

• Direct diode laser current modulation lacks precise amplitude and phase control.
• Existing external modulators are often outperformed in key figures of merit for quantum applications.

Purpose of the Study:

• To present simple, low-cost devices for switching, amplifying, and chirping diode lasers.
• To overcome limitations of direct current modulation by exploiting amplifier saturation.
• To develop systems with high power, fast switching, and arbitrary frequency chirps for quantum applications.

Main Methods:

• Utilizing semiconductor optical amplifiers for intensity switching with high ON:OFF ratios (>10^6).
• Employing a tapered amplifier for nanosecond optical pulses with 3W peak power.
• Applying fast RF pulses to laser diodes for frequency shifting (up to 300 MHz) and chirping (150 MHz/ns).

Main Results:

• Achieved ON:OFF ratios >10^6 in 50 ns using optical amplifiers.
• Generated 3W peak power optical pulses with nanosecond durations.
• Demonstrated frequency chirping up to 150 MHz/ns with <2% intensity variation.
• Combined components to produce watt-level optical pulses with arbitrary frequency chirps within 65 ns.

Conclusions:

• Developed novel, low-cost diode laser modulation devices.
• These devices significantly outperform conventional modulators for quantum technological applications.
• The systems are suitable for fast experiments requiring high power and low noise, such as quantum memory experiments.