Characterisation of periodically poled materials using nonlinear microscopy

Abstract

Periodically poled crystalline materials are extremely attractive for processes such as second harmonic generation and optical parametric generation due to their very high conversion efficiency. For optimal performance, fabrication of poled regions with sub-micron tolerance is required. In this paper we introduce multi-photon laser scanning luminescence microscopy as a powerful minimally-invasive measurement technique which provides information about internal device structure with high spatial resolution that cannot be easily obtained with existing methods. A comparative study of confocal and multi-photon imaging of periodically poled crystalline materials is also performed.

Three-dimensional ferroelectric domain visualization by Čerenkov-type second harmonic generation

“…The details about when, where and how these processes occur are largely unexplored as this requires accurate three-dimensional (3D) visualization of the inverted domains. So far, only few techniques have been used for 3D observations [20,21,22,23,24,25], and their application was determined by the type of the media [21,22], the thickness of the sample [21], and the presence of the reference plate [25]. Moreover, as all the existing studies were limited to 1D NPS, even less is known about internal domain structure in NPS with 2D periodicity, thus preventing further optimization of the fabrication process, designing more complex structures for advanced applications and finally understanding the origin of defect formation.…”

Optical studies of ferroelectric and ferroelastic domain walls

“…magnesium which reduces optical damage upon high power laser irradiation. Multiphoton laser scanning luminescence microscopy measurements in 5% magnesium-doped LiNbO 3 reveal a clear contrast at domain walls [139], tentatively attributed to higher dopant concentrations [139], based on the fact that, in this regime, the luminescence intensity scales with magnesium concentration [140,141]. However, internal field variations and local changes in strain could also play a role [140,141].…”

Observation of spontaneous polarization misalignments in periodically poled crystals using second-harmonic generation microscopy

“…But these techniques lack three-dimensional resolution and provide little information of internal structures. More recently, 3D microscopy techniques, such as refractive coupling method [18,19], confocal laser scanning microscopy [20], twophoton luminescence microscopy [21], SHG microscopy/interferometry [22][23][24][25][26], and very recently, optical coherence tomography [27] were adopted to study PPC. Sub-μm resolution of 3D domain structures has been achieved with these scanning microscopies.…”