Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

Abstract

Lithium niobate on insulator (LNOI) technology is revolutionizing the lithium niobate industry, enabling higher performance, lower cost and entirely new devices and applications. The availability of LNOI wafers has sparked significant interest in the platform for integrated optical applications, as LNOI offers the attractive material properties of lithium niobate, while also offering the stronger optical confinement and a high optical element integration density that has driven the success of more mature silicon and silicon nitride (SiN) photonics platforms. Due to some similarities between LNOI and SiN, established techniques and standards can readily be adapted to the LNOI platform including a significant array of interface approaches, device designs and also heterogeneous integration techniques for laser sources and photodetectors. In this contribution, we review the latest developments in this platform, examine where further development is necessary to achieve more functionalities in LNOI integrated optical circuits and make a few suggestions of interesting applications that could be realized in this platform.

Opportunities for photonic integrated circuits in optical gas sensors

“…The supported wavelength region of several waveguide materials in the visible range, up to the mid-infrared region, is shown in figure 10. Current research includes the use of lithium niobate (LiNbO 3 ), which is transparent at the VIS and mid-infrared wavelength regime [62,63]. However, Si 3 N 4 platforms are the only ones currently available for multi-project wafer (MPW) runs, supporting VIS waveguides.…”

Research of selective etching in LiNbO3 using proton-exchanged wet etching technique

“…Lithium niobate (LN), known as the optical silicon in the current optoelectronics age, is one of the most widelyused materials for the fabrication of integrated optical devices because of its commercial availability and multifunctional properties [1], such as the excellent transparency from visible to infrared light, high nonlinearity and large electro-optical coefficient [2]. During the past decades, LN material has drawn great attentions in realizing high-density integrated photonic/optical circuits due to its high performance [3], especially with the occurrence of a newly-arisen optical material, namely, lithium niobate-on-insulator (LNOI). However, the LN material is chemically inert, as a result, it can hardly be etched without any pre-treatments.…”

“…For LNOI platform, high difference of refractive index contrast of the fabricated channel waveguides is obtained due to its unique structure, leading to a better optical confinement in a much smaller volume. To realize the ultra-compact integrated photonic circuits, several kinds of etching methods have been reported to fabricate high refractive index difference waveguides based on the LN material, such as reactive ion beam etching (RIE), inductively coupled plasma etching (ICP-RIE), focused ion milling (FIB), and wet etching and so on [3][4][5]. Nevertheless, some inevitable problems exist in these etching methods.…”

Lithium Niobate Metasurfaces

“…Just like silicon as the backbone of electronic industry, LN acts as a multipurpose material platform for photonics and optoelectronic systems . During the past decades, most of the attention was drawn to realize high‐density integrated photonic/optical circuits using LN . But LN is chemically inert, so it cannot be chemically etched.…”

“…[6] During the past decades, most of the attention was drawn to realize high-density integrated photonic/optical circuits using LN. [7,8] But LN is chemically inert, so it cannot develop the next generation of metasurfaces based on various ferroelectric crystals.…”