Freely designable optical frequency conversion in Raman-resonant four-wave-mixing process

Abstract

Nonlinear optical processes are governed by the relative-phase relationships among the relevant electromagnetic fields in these processes. In this Report, we describe the physics of arbitrary manipulation of Raman-resonant four-wave-mixing process by artificial control of relative phases. As a typical example, we show freely designable optical-frequency conversions to extreme spectral regions, mid-infrared and vacuum-ultraviolet, with near-unity quantum efficiencies. Furthermore, we show that such optical-frequency conversions can be realized by using a surprisingly simple technology where transparent plates are placed in a nonlinear optical medium and their positions and thicknesses are adjusted precisely. In a numerical simulation assuming practically applicable parameters in detail, we demonstrate a single-frequency tunable laser that covers the whole vacuum-ultraviolet spectral range of 120 to 200 nm.

Tailored Raman-resonant four-wave-mixing processes

“…This experimental demonstration is regarded as a proof of principle for the study on tailoring high-order Raman-resonant four-wave-mixing processes which was investigated on the basis of numerical calculations in Ref. 1. The conceptual idea can be applied to a variety of nonlinear optical processes [25].…”

“…Energy flows among such electromagnetic fields (energy flow from one mode in the electromagnetic fields to another) occur via this nonlinear polarization, P NL , and these energy flows are strongly dominated by the phase relationships among the relevant electromagnetic fields, a, b, etc., including the phase of nonlinear polarization, . This suggests that if it is possible to freely manipulate these phase relationships at various interaction lengths, we should be able to tailor this nonlinear optical process in a variety of ways [1]. This idea itself is general, and thereby it is possible in principle to apply this conceptual idea to a variety of nonlinear optical processes.…”

“…In the present study, we apply this conceptual idea to a Raman-resonant four-wave-mixing process and investigate it both theoretically and experimentally. Zheng and Katsuragawa Recently, it has been shown that incident electromagnetic field energy can be converted with near-unity quantum efficiency to an intended high-order anti-Stokes or Stokes mode by implementing these relative-phase manipulations in the Raman-resonant four-wave-mixing process in gaseous para-hydrogen [1]. In the same study, they also showed the potential to realize a single-frequency tunable laser that can cover an entire ultra-broad spectral region from 120 nm in the vacuum ultraviolet to the mid infrared.…”

10 W injection-locked single-frequency continuous-wave titanium:sapphire laser

“…Injection-locked Ti:sapphire lasers [7] have the advantage that their spectrum and power can be independently controlled. Dual-wavelength injection locking of Ti:sapphire lasers [8,9] has also been demonstrated and applied to Ramanresonant four-wave-mixing [10]. Since injection-locking makes it possible to omit wavelengthselective elements inside laser cavities, the laser efficiency can also be improved.…”

Enhancement of the phase conjugation degenerate four-wave mixing using the Bessel beam

“…Four-wave mixing (FWM) is a kind of third-order nonlinear process in which three beams interact with the nonlinear medium and a fourth beam (FWM signal) is generated when the phase-matching condition is satisfied. FWM has a variety of applications, such as squeezed states of light [15], wavelength conversion [16], isotope selective analysis and determination [17,18], and image reconstruction [19,20]. In particular, degenerate FWM (DFWM) is a superb method to generate a phase-conjugate beam, in which a probe beam intersects two counter-propagating pump beams, and the DFWM signal is generated in the opposite direction of the probe beam.…”