Phase sensitive amplification with noise figure below the 3 dB quantum limit using CW pumped PPLN waveguide.

Area of Science:

• Photonics and Optical Engineering
• Quantum Optics

Background:

• Phase sensitive amplifiers (PSAs) are crucial for low-noise signal amplification.
• Achieving noise figures below the 3 dB quantum limit is a significant challenge in optical systems.

Purpose of the Study:

• To evaluate the noise figure (NF) of a phase sensitive amplifier (PSA) in both optical and electrical domains.
• To demonstrate the potential of PSA technology for high-sensitivity signal detection.

Main Methods:

• Phase sensitive amplification was achieved using degenerate parametric amplification in a periodically poled LiNbO3 (PPLN) waveguide.
• Second harmonic pumping of the PPLN waveguide allowed direct observation of intrinsic amplified spontaneous emission (ASE).
• Noise figure was determined by intrinsic ASE measurements and validated by electrical domain noise floor measurements of cascaded amplifiers.

Main Results:

• An intrinsic noise figure below the 3 dB quantum limit was successfully obtained.
• The low noise performance was confirmed through cascaded PSA and erbium-doped fiber amplifier measurements.
• The PSA demonstrated improved sensitivity when used as a preamplifier for a 40 Gbit/s phase shift keying signal.

Conclusions:

• The developed PSA exhibits excellent low-noise characteristics, surpassing the quantum limit.
• Second harmonic pumping is an effective method for characterizing PSA noise performance.
• The PSA shows significant promise for enhancing the sensitivity of high-speed optical communication systems.