Detail Project and Funding

Abstract: In this project we plan to develop and experimentally realize methods for efficient conversion of near-IR frequency combs into the mid IR, and to explore methods in which the nonlinear crystal can also provide spectral and temporal shaping for the converted comb. Our emphasis is on generating combs at the 3.5-4.5 μm region. The nonlinear conversion will be based on MgO:CLN crystals, which have relatively low absorption in this range as well as high nonlinear coefficient. The adiabatic conversion and the spectral shaping will be achieved by designing suitable nonlinear modulation patterns, followed by electric field poling of the nonlinear crystals. The special design of the nonlinear crystal ensures high conversion efficiency and a reduced dependence of the conversion efficiency on operating conditions (e.g. pump wavelength, crystal temperature, tilt angle, etc.). This wide tuning capability represents the main advantage of this approach, allowing the simultaneous generation of a broad spectrum of radiation with significant power. In addition, the introduction of spectral shaping capabilities, which will be experimentally studied for the first time with ultrashort pulses, will enable to selectively convert light into spectral region of interest.
Both the Italian and Israeli partners have world-wide recognised leadership in the scientific fields of the project. In particular, the Israeli partner is leader in the design and development of nonlinear devices for multifunctional purposes. Among the main scientific results we find the first nonlinear generation of accelerating Airy beams, generation and all-optical manipulation of beam parameters such as acceleration and topological charge, development of nonlinear computer generated holograms for shaping beams in the spatial and spectral domains, etc. As mentioned above, the Israeli team participated in the development and first experimental realizations of the concept of adiabatic frequency conversion, and recently introduced the concept of nonlinear spectral holography. The Italian partner has recognised competences in the use and development of optical frequency combs for precision spectroscopy and metrology, in nonlinear frequency conversion, in the implementation of high-sensitivity spectroscopic techniques as cavity-enhanced or cavity ring-down spectroscopy, Doppler-free detection, frequency modulation.
The two groups, which have successfully collaborated in a number of projects in the past, provide synergetic expertise: the Israeli group in the field of nonlinear conversion and spectral shaping, the Italian team in the fields of frequency combs and laser spectroscopy.
In particular, the objectives of the proposed research project include:

Design and optimization of nonlinear crystals for adiabatic nonlinear frequency mixing of a near-IR fs laser and near-IR pump laser for the generation of a mid-IR (3.5-4.5 μm) frequency comb;
Fabrication and characterization of the designed crystals: operating conditions, bandwidth;
Generation and characterization of the mid-IR comb: spectral broadening, average power, stability;
Design and optimization of nonlinear crystals for spectral shaping of the mid-IR light (based on mixing a near-IR ultrashort pulse and a near IR pump laser).
Fabrication and characterization of the designed crystals;
Generation and characterization of the generated mid-IR signal: power and spectral shape.

Given the broad spectrum of possible applications of both the developed crystals and the generated optical sources, the project will serve as the starting point of additional future projects and collaborations. We expect that the incoming results will form the basis for future joint proposals by the partners involved in the project.

INO’s Experiments/Theoretical Study correlated:
Optical frequency comb generation in the mid IR