An official website of the United States government
Silicon carbide (SiC) has great potential for optomechanical applications due to its outstanding optical and mechanical properties. However, challenges associated with SiC nanofabrication have constrained its adoption in optomechanical devices, as embodied by the considerable optical loss or lack of integrated optical access in existing mechanical resonators. In this work, we overcome such challenges and demonstrate a low-loss, ultracompact optomechanical resonator in an integrated 4H-SiC-on-insulator (4H-SiCOI) photonic platform for the first time, to our knowledge. Based on a suspended 4.3-μm-radius microdisk, the SiC optomechanical resonator features low optical loss (<1 dB/cm), a high mechanical frequencyfmof 0.95×109 Hz, a mechanical quality factorQmof 1.92×104, and a footprint of <1×10−5 mm2. The correspondingfm·Qmproduct is estimated to be 1.82×1013 Hz, which is among the highest reported values of optomechanical cavities tested in ambient environment at room temperature. In addition, the strong optomechanical coupling in the SiC microdisk enables coherent regenerative optomechanical oscillations at a threshold optical dropped power of 14 μW, which also supports efficient harmonic generation at increased power levels. With such competitive performance, we envision a range of chip-scale optomechanical applications to be enabled by the low-loss 4H-SiCOI platform.
more »
« less
Investigation of the electro-optic effect in high-Q 4H-SiC microresonators
Silicon carbide (SiC) recently emerged as a promising photonic and quantum material owing to its unique material properties. In this work, we carried out an exploratory investigation of the Pockels effect in high-quality-factor (high-Q) 4H-SiC microresonators and demonstrated gigahertz-level electro-optic modulation for the first time. The extracted Pockels coefficients show certain variations among 4H-SiC wafers from different manufacturers, with the magnitudes ofr13andr33estimated to be in the range of (0.3–0.7) pm/V and (0–0.03) pm/V, respectively.
more »
« less
- Award ID(s):
- 2127499
- PAR ID:
- 10400974
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 48
- Issue:
- 6
- ISSN:
- 0146-9592; OPLEDP
- Format(s):
- Medium: X Size: Article No. 1482
- Size(s):
- Article No. 1482
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Superior infrared nonlinear optical (NLO) crystals are in urgent demand in the development of lasers and optical technologies for communications and computing. The critical challenge is to find a crystal with large non‐resonant phase‐matchable NLO coefficients and high laser damage threshold (LDTs) simultaneously, which however scale inversely. This work reports such a material, MgSiP2,that exhibits a large second harmonic generation (SHG) coefficient ofd14≈d36= 89 ± 5 pm V−1at 1550 nm fundamental wavelength, surpassing the commercial NLO crystals AgGaS2, AgGaSe2, and ZnGeP2. First principles theory reveals the polarizability and geometric arrangement of the [SiP4] tetrahedral units as the origin of this large nonlinear response. Remarkably, it also exhibits a high LDT value of 684 GW cm−2, which is six times larger than ZnGeP2and three times larger than CdSiP2. It has a wide transparency window of 0.53–10.35 µm, allowing broadband tunability. Further, it is Type I and Type II phase‐matchable with large effective SHG coefficients ofdeff,I≈80.2 pm V−1anddeff,II≈73.4 pm V−1. The outstanding properties of MgSiP2make it a highly attractive candidate for optical frequency conversion in the infrared.more » « less
-
Hexagonal semiconductors such as GaN and SiC have important power applications at radio and millimeter-wave (mmW) frequencies. They are characterized by both ordinary and extraordinary permittivities, parallel and perpendicular to the densest packed c plane, respectively. However, due to the challenges of high-frequency measurements, little reliable data exist for these permittivities especially at mmW frequencies. Recently, for the first time, we reported the extraordinary permittivity of 4H SiC at mmW frequencies using substrateintegrated waveguides. We now report the ordinary permittivity of the same material using several Fabry-Perot resonators to cover most mmW frequencies. The resulted relative ordinary permittivity of 9.76 ± 0.01 exhibits little dispersion and is significantly lower than the previously reported extraordinary permittivity of 10.2 ± 0.1. This confirms that both ordinary and extraordinary permittivities are needed for accurate design and model of devices fabricated on 4H SiC. By contrast, the measured loss tangent increases linearly from 3 10−5 to 1.6 10−4 from 55 GHz to 330 GHz and can be fitted with (4.9 ± 0.1) 10−16 f, where f is the frequency in Hz. In fact, 4H SiC is the lowest-loss solid we have ever measured. The present approaches for permittivity characterization can be extended to other solids.more » « less
-
Hexagonal semiconductors such as 4H SiC have important high-frequency, high-power, and high-temperature applications. The applications require accurate knowledge of both ordinary and extraordinary relative permittivities, ε and ε||, perpendicular and parallel, respectively, to the c axis of these semiconductors. However, due to challenges for suitable test setups and precision high-frequency measurements, little reliable data exists for these semiconductors especially at millimeter-wave frequencies. Recently, we reported ε|| of 4H SiC from 110 to 170 GHz. This paper expands on the previous report to include both ε and ε|| of the same material from 55 to 330 GHz, as well as their temperature and humidity dependence enabled by improving the measurement precision to two decimal points. For example, at room temperature, real ε and ε|| are constant at 9.77 ± 0.01 and 10.20 ± 0.05, respectively. By contrast, the ordinary loss tangent increases linearly with the frequency f in the form of (4.9 ± 0.1) 10−16 f. The loss tangent, less than 1 10−4 over most millimeter-wave frequencies, is significantly lower than that of sapphire, our previous low-loss standard. Finally, both ε and ε|| have weak temperature coefficients on the order of 10−4 /°C. The knowledge reported here is especially critical to millimeter-wave applications of 4H SiC, not only for solid-state devices and circuits, but also as windows for high-power vacuum electronics.more » « less
-
For millimeter-wave power applications, GaN high-electron mobility transistors (HEMTs) are often grown epitaxially on a high-purity semi-insulating c-axis 4H-SiC substrate. For these anisotropic hexagonal materials, the design and modeling of microstrip and coplanar interconnects require detailed knowledge of both the ordinary permittivity ε⊥ and the extraordinary permittivity εǁ perpendicular and parallel, respectively, to the c-axis. However, conventional dielectric characterization techniques make it difficult to measure εǁ alone or to separate εǁ from ε⊥. As a result, there is little data for εǁ, especially at millimeter-wave frequencies. This work demonstrates techniques for characterizing εǁ of 4H SiC using substrate-integrated waveguides (SIWs) or SIW resonators. The measured εǁ on seven SIWs and eleven resonators from 110 to 170 GHz is within ±1% of 10.2. Because the SIWs and resonators can be fabricated on the same SiC substrate together with HEMTs and other devices, they can be conveniently measured on-wafer for precise material-device correlation. Such permittivity characterization techniques can be extended to other frequencies, materials, and orientations.more » « less
