Ultra-stable clock laser system development towards space applications.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Space Science and Technology

Background:

• Optical lattice clocks are advancing for space applications, necessitating development of space-compatible components.
• Key requirements for space-based optical clocks include power efficiency, radiation hardening, reduced size, lower weight, and enhanced mechanical stability.

Purpose of the Study:

• To develop a space-compatible interrogation laser system for a strontium lattice clock within the Space Optical Clock (SOC2) project.
• Focus on enhancing mechanical rigidity and minimizing the physical size of the laser system.

Main Methods:

• Utilized a single extended cavity diode laser for sufficient power for atomic interrogation, frequency comb comparison, and diagnostics.
• Implemented fiber link stabilization to connect to the atomic package and frequency comb.
• Designed a compact optics module (60x45x8 cm³) and an ultra-stable reference cavity with vacuum system (30x30x30 cm³).

Main Results:

• Achieved a fractional frequency instability of 7.9 × 10⁻¹⁶ at 300 ms averaging time.
• The laser system provides adequate power for clock operation and diagnostics.
• Measured low acceleration sensitivities of the reference cavity: 3.6 × 10⁻¹⁰/g, 5.8 × 10⁻¹⁰/g, and 3.1 × 10⁻¹⁰/g.

Conclusions:

• The developed laser system meets critical requirements for space-based strontium lattice clocks, particularly in terms of mechanical stability and size.
• This system is a significant step towards realizing high-performance atomic clocks in space environments.
• The achieved performance and compact design pave the way for future space missions utilizing optical clock technology.