Laser beam characterization for experiments in quantum optics

Ultrafast laser-based micromanufacturing is essential for fabricating high-precision quantum devices such as quantum gates, photonic circuits, and waveguides. Besides the area of micromachining, recent applications of laser beams also include quantum imaging and sensing. The laser beams have been characterized for their wavelength and pulse durations. The techniques include homemade setups of intensity autocorrelation, frequency-resolved optical gating (FROG), and spectral phase interferometry for direct electric-field reconstruction (SPIDER) besides the commercial spectrographs. Beams obtained from non-collinear optical parametric amplifier (NOPA) capable of delivering tunable ultrafast pulses are also described. The dark core beams through Hermite Gaussian (HG) modes and thermal effects are also generated. All these beams are capable of generating polarization-entangled photons by the nonlinear-optical phenomenon of spontaneous parametric down-conversion (SPDC). After describing the construction of the entangled photon source (EPS), an interferometric setup for imaging based on extracting the phase and intensity of an object is discussed. The application areas of the EPS for quantum imaging, multi-photon applications and adaptive imaging are also highlighted. We propose that quantum imaging can overcome the existing challenges of real-time feedback during micromanufacturing and help prevent the wastage of resources.