Photonic Laser Integration for Metrology and Quantum Systems

Introduction

In LASIQ I will develop, for the first time, an on-chip titanium-sapphire mode-locked laser capable of generating low-noise optical frequency combs in the 650-1100 nm wavelength range.

Optical Frequency Comb Generators

Optical frequency comb generators are light sources capable of generating a spectrum of millions of equally spaced laser lines. Such light sources allow for:

1. Down-converting optical frequencies (THz) to the microwave domain (GHz).
2. Enabling precision laser spectroscopy.
3. Constructing optical atomic clocks.

Theodor Hänsch and John Hall were awarded the Nobel Prize in Physics in 2005 for developing the optical frequency comb in recognition of its impact on quantum metrology, timekeeping, and fundamental physics. Since their initial development, they have revolutionized several other fields such as:

• LIDAR (light detection and ranging)
• Molecular spectroscopy
• Astronomic spectroscopy for exoplanet identification
• Ultra-low-noise microwave generation

Challenges with Current Systems

However, high-performance optical frequency combs are mostly based on expensive (>100 kEUR) and bulky (> 900 cm³) free-space or fiber-based mode-locked laser systems, which strongly limits their use in real-world applications. This has spurred an enormous research effort towards developing on-chip optical frequency comb generators.

Currently, a large variety of integrated optical comb generators have been demonstrated, ranging from soliton microcombs to semiconductor mode-locked lasers. However, so far integrated optical comb generators cannot rival the performance of their table-top counterparts, severely limiting their application.

Project Goals

In LASIQ, I will address this need by demonstrating titanium-sapphire mode-locked lasers on a millimeter-sized chip with a performance similar to that of the incumbent free-space solution.

Potential Applications

The realization of an on-chip titanium-sapphire mode-locked laser will enable:

• Chip-scale supercontinuum sources
• Integrated optical coherence tomography systems
• On-chip optical atomic clocks
• Dual-comb metrology