Polarization-dependent noise in photon-number squeezed light generated by quantum-well lasers.

Area of Science:

• Quantum optics
• Semiconductor lasers

Background:

• Nonclassical light generation is crucial for quantum technologies.
• Quantum-well lasers offer a compact source for nonclassical light.
• Characterizing noise in laser output is essential for understanding performance.

Purpose of the Study:

• To analyze amplitude noise spectra from a quantum-well laser.
• To investigate polarization-dependent noise characteristics.
• To demonstrate sub-shot-noise photon-number fluctuations.

Main Methods:

• Injection-locking a low-temperature quantum-well laser.
• Analyzing output along orthogonal polarization axes.
• Employing polarization-preserving balanced homodyne detection.

Main Results:

• Observed correlated polarization-dependent amplitude noise.
• Achieved photon-number fluctuations 4.5 dB below the shot-noise limit.
• Attributed noise to polarization mixing and gain medium correlations.

Conclusions:

• Balanced homodyne detection effectively suppresses polarization effects.
• Correlated fluctuations in the gain medium are a significant noise source.
• Demonstrated a practical method for generating squeezed light from quantum-well lasers.