Robust and broadband frequency conversion in composite crystals with tailored segment widths and χ(2) nonlinearities of alternating signs.

We propose an efficient, robust, and broadband nonlinear optical frequency conversion technique, which uses segmented crystals constructed in analogy with the composite pulses in nuclear magnetic resonance and quantum optics. The composite crystals are made of several macroscopic segments of nonlinear susceptibilities of opposite signs and specific thicknesses, which are determined from the condition to maximize the conversion efficiency with respect to variations in the experimental parameters. These crystals deliver broadband operation for significantly lower pump intensities than single bulk crystals. We demonstrate this technique by numerical simulation of sum-frequency generation in MgO:LiNbO3 crystal.

Highly efficient broadband polarization retarders and tunable polarization filters made of composite stacks of ordinary wave plates.

By using the formal analogy between the evolution of the state vector in quantum mechanics and the Jones vector in polarization optics, we construct and demonstrate experimentally efficient broadband half-wave polarization retarders and tunable narrowband polarization filters. Both the broadband retarders and the filters are constructed by the same set of stacked standard multiorder optical wave plates (WPs) rotated at different angles with respect to their fast polarization axes: for a certain set of angles this device behaves as a broadband polarization retarder, while for another set of angles it turns into a narrowband polarization filter. We demonstrate that the transmission profile of our filter can be centered around any desired wavelength in a certain vicinity of the design wavelength of the WPs solely by selecting appropriate rotation angles.

Efficient broadband composite optical isolator.

A new design of a broadband optical isolator, composed as a sequence of ordinary Faraday rotators and achromatic quarter-wave plates (QWPs), is presented. In particular, we demonstrate that by using four Faraday rotators and six achromatic QWPs, rotated at specific angles, optical isolation better than 15 dB over the range from 700 to 1000 nm can be achieved. The measured transmittance (corrected for absorption and reflection) in the forward direction over the same wavelength range shows broadening of the transmission spectrum compared with the one of a single Faraday rotator.

Coherent excitation of a two-state system by a linearly chirped Gaussian pulse.

This work presents an analytic description of coherent excitation of a two-state quantum system by an external field with a Gaussian temporal shape and a linear frequency sweep. A very accurate analytic approximation to the transition probability in terms of the Lambert function is derived by using the Dykhne-Davis-Pechukas approach. This approximation provides analytic expressions for the frequency and the amplitude of the probability oscillations and for the ranges of interaction parameters where high transition probability is obtained.

Preparation of entangled states by adiabatic passage.

We propose a novel technique for the creation of entangled pairs of two-state systems based upon adiabatic passage induced by a suitably crafted time-dependent external field.

Laser-induced population transfer by adiabatic passage techniques.

We review some basic techniques for laser-induced adiabatic population transfer between discrete quantum states in atoms and molecules.