Phase measurement in frequency-doubling fibers

Area of Science:

• Nonlinear Optics
• Fiber Optics
• Laser Physics

Background:

• Second-harmonic generation (SHG) is a key nonlinear optical process.
• Controlling phase shifts in SHG is crucial for applications.
• Nd:YAG lasers are commonly used for fundamental light sources.

Purpose of the Study:

• To prepare optical fibers for second-harmonic generation.
• To precisely measure the relative phase shift between seed and second-harmonic light.
• To investigate the physical consequences of a measured phase shift.

Main Methods:

• Injecting a frequency-doubled seed signal with fundamental light from a Nd:YAG laser.
• Utilizing a water cell to sweep the relative phase with interferometric precision.
• Measuring the relative phase shift between seed and generated second-harmonic light.

Main Results:

• The relative phase shift was measured to be approximately 99 +/- 9.2 degrees, close to 90 degrees (pi/2).
• Interferometric precision was achieved using a water cell for phase sweeping.
• The study identified potential physical consequences of this specific phase shift.

Conclusions:

• A precise measurement of a near 90-degree phase shift in SHG within optical fibers was achieved.
• The experimental setup allowed for precise control and measurement of phase shifts.
• The findings contribute to understanding phase-dependent phenomena in nonlinear fiber optics.