Absolute frequency references at 1529 and 1560 nm using modulation transfer spectroscopy.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Spectroscopy
• Metrology

Background:

• Precise optical frequency standards are crucial for advanced applications like optical communications and fundamental physics.
• Existing standards may lack simplicity, robustness, or coverage of specific critical wavelengths.
• Rubidium-87 (87Rb) spectroscopy offers a well-characterized atomic system for frequency stabilization.

Purpose of the Study:

• To demonstrate a dual-band optical frequency reference operating at 1529 nm and 1560 nm within the telecom C-band.
• To utilize 87Rb modulation transfer spectroscopy for high-precision frequency stabilization.
• To analyze the stability and accuracy limitations of the proposed reference system.

Main Methods:

• Employing 87Rb modulation transfer spectroscopy to lock two distinct optical transitions.
• Utilizing a two-level transition (5S(1/2)F=2→5P(3/2)F'=3) and a ladder transition (5S(1/2)F=2→5P(3/2)F'=3→4D(5/2)F''=4).
• Investigating sensitivity to probe power, magnetic field fluctuations, residual amplitude modulation, and gas collisions.

Main Results:

• Successful demonstration of two optical frequency references at 1529 nm and 1560 nm.
• Quantification of frequency shifts due to various environmental factors and technical imperfections.
• Estimation of short-term Allan deviation from the error signal slope.

Conclusions:

• The developed scheme offers a simple and high-performing system for optical frequency references at key telecom wavelengths.
• An absolute accuracy of approximately 1 kHz is deemed realistic for this system.
• This work provides a valuable tool for applications requiring stable and accurate optical frequencies in the C-band.