High sensitive label-free optical sensor based on Goos-Hänchen effect by the single chirped laser pulse

Area of Science:

• Quantum optics
• Molecular spectroscopy
• Nanoscale sensing

Background:

• Four-level molecular systems are crucial for understanding light-matter interactions.
• Goos-Hänchen (GH) shifts are sensitive optical phenomena used in sensing applications.

Purpose of the Study:

• To investigate the Goos-Hänchen (GH) shifts in a four-level molecular system within a cavity.
• To analyze the sensor's performance for detecting biological molecules based on refractive index changes.

Main Methods:

• Modeling a four-level molecular system with two ground and two excited vibrational states in a constant cavity.
• Analyzing reflected and transmitted GH shifts for single-chirped laser pulses (positive and negative).
• Investigating the influence of laser field detuning, intensity, and chirp rate on GH shifts.

Main Results:

• The sensor's sensitivity to the intracavity medium's refractive index is demonstrated.
• Coherent control of the refractive index by medium parameters is achieved.
• The sensor exhibits high sensitivity to low concentrations of biological molecules.

Conclusions:

• A four-level molecular system in a cavity can function as a sensitive biosensor.
• The sensor's effectiveness is particularly pronounced for detecting low concentrations of biological samples.
• Variations in sample concentration significantly impact GH shifts, enabling precise detection.