Aluminum nitride as a new material for chip-scale optomechanics and nonlinear optics

Abstract

Silicon photonics has offered a versatile platform for the recent development of integrated optomechanical circuits. However, silicon is limited to wavelengths above 1.1 µm and does not allow device operation in the visible spectrum range where low-noise lasers are conveniently available. The narrow bandgap of silicon also makes silicon optomechanical devices susceptible to strong two-photon absorption and free carrier absorption, which often introduce strong thermal effects that limit the devices' stability and cooling performance. Further, silicon also does not provide the desired lowest order optical nonlinearity for interfacing with other active electrical components on a chip. On the other hand, aluminum nitride (AlN) is a wide-band semiconductor widely used in micromechanical resonators due to its low mechanical loss and high electromechanical coupling strength. In this paper, we report the development of AlN-on-silicon platform for low loss, wide-band optical guiding, as well as its use for achieving simultaneously high-optical-qualityfactor and high-mechanical-quality-factor optomechanical devices. Exploiting AlN's inherent second-order nonlinearity we further demonstrate electro-optic modulation and efficient second harmonic generation in AlN photonic circuits. 2Our results suggest that low-cost AlN-on-silicon photonic circuits are excellent substitutes for complementary metal-oxide-semiconductor-compatible photonic circuits for building new functional optomechanical devices that are free from carrier effects. Contents

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…[292] Combined with its potential for lasers and detectors, AlN may someday enable photonic integrated circuit platforms for quantum information processing, including those involving trapped ions. [293] …”

On-Chip Strong Coupling and Efficient Frequency Conversion between Telecom and Visible Optical Modes

“…In this Letter, we demonstrate coherent interaction between photons of different colors on a scalable aluminum nitride-on-insulator [12] chip based on χ (2) optical nonlinearity. The nonlinear optic induced transparency (NOIT), as an analogue to electromagnetically induced transparency resulting from coherent photon-atom [5] or photon-phonon interactions [17][18][19][20], is reported.…”

“…Second order optical nonlinearity (χ (2) ) is one of the most widely explored properties in photonics, utilizing various nonlinear materials [8][9][10][11][12][13]. χ (2) nonlinearity enables the coupling between photons with very different colors, acting as the basis for many important applications such as second harmonic generation, spontaneous parametric down conversion, optical parametric amplification and oscillation.…”

Time-reversal symmetry breaking with acoustic pumping of nanophotonic circuits

“…This selection of materials ensures CMOS compatibility [28]. Here, the AlN supports the optical modes due to its high transparency in the telecom band [28,29] and additionally functions as an excellent acoustic material on which phonons can be piezoelectrically driven (Fig. 2c,d) [30][31][32].…”