Fabrication of ridge waveguides in zinc-substituted lithium niobate by means of ion-beam enhanced etching

Abstract

We present results on the fabrication and characterization of ridge waveguides in zinc-substituted lithium niobate. High-quality waveguides were fabricated by a combination of liquid-phase epitaxy and multiple applications of ion-beam enhanced etching. The two major demands on ridge waveguides, a very low side-wall roughness and a rectangle shape with side-wall angles close to 90 degrees , were realized simultaneously by using this technique. Single-mode waveguiding at a wavelength of 1064 nm was demonstrated with attenuation values of 0.9 dB/cm.

Characterization of selective etching and patterning by sequential light- and heavy-ion irradiation of LiNbO3

“…One approach to mitigate such an undercut feature is to use multiple Ar + irradiation cycles [6]. In particular, if the sample is exposed to multiple irradiation steps, each having different Ar + energies, a more uniformly-distributed amorphous layer extending from the surface to the ion stopping range should be formed in the unmasked region.…”

“…For example, it was found [5] that the etching rate in 5-MeV-Si-irradiated X-cut LiNbO 3 was $100 nm/min. This radiation-enabled selective etching thus has the potential for fabricating nano-or micro-structured photonic devices, such as ridge or one-dimensional (1D) photonic crystal waveguides [6][7][8]. This heavy-ion-enabled research demonstrates the potential of this etching method.…”

Deep anisotropic LiNbO3 etching with SF6/Ar inductively coupled plasmas

“…Wet etching, combined with a variety of methods, including proton exchange, 7 ion implantation, 8,9 metal deposition, 10,11 and domain inversion 12 has been reported to fabricate ridge LiNbO 3 waveguides in recent decades. Wet etching, based on a mixture of HF and HNO 3 , is a simple process for etching LiNbO 3 .…”

Effect of 120MeV Ag9+ ion irradiation of YCOB single crystals

“…As a consequence, the damaged regions are etched in hydrofluoric solution (HF) without affecting the non irradiated crystal [8][9][10][11]. In combination with selective ion irradiation using standard masking technologies the fabrication of high quality micro-and nano-structures in LiNbO 3 is achieved [12,13].…”