Advances in lithium niobate thin-film lasers and amplifiers: a review

Abstract

.Lithium niobate (LN) thin film has received much attention as an integrated photonic platform, due to its rich and great photoelectric characteristics, based on which various functional photonic devices, such as electro-optic modulators and nonlinear wavelength converters, have been demonstrated with impressive performance. As an important part of the integrated photonic system, the long-awaited laser and amplifier on the LN thin-film platform have made a series of breakthroughs and important progress recently. In this review paper, the research progress of lasers and amplifiers realized on lithium niobate thin film platforms is reviewed comprehensively. Specifically, the research progress on optically pumped lasers and amplifiers based on rare-earth ions doping of LN thin films is introduced. Some important parameters and existing limitations of the current development are discussed. In addition, the implementation scheme and research progress of electrically pumped lasers and amplifiers on LN thin-film platforms are summarized. The advantages and disadvantages of optically and electrically pumped LN thin film light sources are analyzed. Finally, the applications of LN thin film lasers and amplifiers and other on-chip functional devices are envisaged.

Low-Threshold Anti-Stokes Raman Microlaser on Thin-Film Lithium Niobate Chip

“…This on-chip upconverted anti-Stokes Raman laser was attributed to the excitation of strong Raman-gain vibration frequency by aligning the Raman photon to the ultra-high-Q (>4 × 10 6 ) WGMs in the TFLN microdisk fabricated by the femtosecond laser PLACE technique. It is worth noting that the pure TFLN cannot provide optical gain for gain directly, because it is an indirect band-gap material [ 20 ]. When combining this blue-shifted laser with the strong electro-optic, piezoelectric, acousto-optic, and second-order nonlinear properties of the TFLN, there will be great improvement in the performance and functionality in TFLN photonic integration, paving the way for high-speed optical information processing and quantum information processing.…”

“…Compared with silica, thin-film lithium niobate (TFLN) is a much stronger Raman-active medium and is more favored for photonic integrated platforms because of its outstanding properties featuring high second-order nonlinearity, large Pockels electro-optic coefficient, and moderate refractive index [ 17 ]. Numerous photonic devices have been demonstrated on the TFLN platform with high performances, ranging from high-speed electro-optical modulators, efficient nonlinear optical frequency convertors, bright quantum light sources, soliton frequency combs, meter-scale length optical waveguide true delay lines, narrow-linewidth microlasers, high-gain waveguide amplifiers, and large-scale photonic integrated circuits [ 17 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Moreover, SRS microlasers [ 4 , 37 , 38 , 39 ] have also been operated on the TFLN platform with a threshold as low as 0.62 mW [ 39 ], resulting from the fabrication of ultra-high-Q microresonators by femtosecond laser photolithography assisted chemo-mechanical etching (PLACE) [ 37 ] to significantly increase the circulating light intensities.…”

Erbium-ytterbium co-doped lithium niobate single-mode microdisk laser with an ultralow threshold of 1 µW

“…Among these devices, singlemode microlasers have been demonstrated in erbium ion-doped microcavities [29][30][31][32][33][34][39][40][41] , serving as coherent light sources operating in the telecom waveband. A threshold as low as 25 μW has been reported [30,42] , and the highest conversion efficiency reached 1.8 × 10 −3 [33] . However, there is still plenty of room for improvement in the conversion efficiency and threshold of single-mode microlasers.…”

Integrating 2D Materials and Plasmonics on Lithium Niobate Platforms for Pulsed Laser Operation at the Nanoscale

“…[ 1–7 ] Among the available photonic platforms, LiNbO 3 (LN) is undergoing a technological revolution motivated by recent breakthroughs in fabrication techniques which enable the availability of high‐quality CMOS‐compatible LN‐on‐insulator thin films. [ 8–11 ] Due to its ultra‐low‐loss modulation and propagation capabilities, and its excellent nonlinear properties, LN has proven to be an outstanding and highly versatile platform to develop a wide variety of integrated photonic components including high‐performance modulators, [ 12,13 ] ultra‐efficient wavelength converters, [ 14,15 ] on‐chip electro‐optics devices, [ 16 ] broadband frequency combs, [ 17 ] or photon‐pair sources, [ 18,19 ] among others. However, despite these advances, the integration of optically active components on photonic integrated circuits (PICs) is still a challenge.…”