More Like this

1. Spin detection with a micromechanical trampoline: towards magnetic resonance microscopy harnessing cavity optomechanics

   https://doi.org/10.1088/1367-2630/ab117a  

   Fischer, R.; McNally, D. P.; Reetz, C.; Assumpção, G. G. T.; Knief, T.; Lin, Y.; Regal, C. A. (April 2019, New Journal of Physics)

   Abstract We explore the prospects and benefits of combining the techniques of cavity optomechanics with efforts to image spins using magnetic resonance force microscopy (MRFM). In particular, we focus on a common mechanical resonator used in cavity optomechanics—high-stress stoichiometric silicon nitride (Si₃N₄) membranes. We present experimental work with a ‘trampoline’ membrane resonator that has a quality factor above 10⁶and an order of magnitude lower mass than a comparable standard membrane resonators. Such high-stress resonators are on a trajectory to reach 0.1 $\mathrm{aN}/\sqrt{\mathrm{Hz}}$force sensitivities at MHz frequencies by using techniques such as soft clamping and phononic-crystal control of acoustic radiation in combination with cryogenic cooling. We present a demonstration of force-detected electron spin resonance of an ensemble at room temperature using the trampoline resonators functionalized with a magnetic grain. We discuss prospects for combining such a resonator with an integrated Fabry–Perot cavity readout at cryogenic temperatures, and provide ideas for future impacts of membrane cavity optomechanical devices on MRFM of nuclear spins. 

   more » « less
2. Deciphering between enhanced light emission and absorption in multi-mode porphyrin cavity polariton samples

   https://doi.org/10.1515/nanoph-2023-0748  

   Odewale, Elizabeth O; Avramenko, Aleksandr G; Rury, Aaron S (March 2024, Nanophotonics)

   It remains unclear how the collective strong coupling of cavity-confined photons to the electronic transitions of molecular chromophore leverages the distinct properties of the polaritonic constituents for future technologies. In this study, we design, fabricate, and characterize multiple types of Fabry-Pérot (FP) mirco-resonators containing copper(II) tetraphenyl porphyrin (CuTPP) to show how cavity polariton formation affects radiative relaxation processes in the presence of substantial non-Condon vibronic coupling between two of this molecule’s excited electronic states. Unlike the prototypical enhancement of Q state radiative relaxation of CuTPP in a FP resonator incapable of forming polaritons, we find the light emission processes in multimode cavity polariton samples become enhanced for cavity-exciton energy differences near those of vibrations known to mediate non-Condon vibronic coupling. We propose the value of this detuning is consistent with radiative relaxation of Herzberg-Teller polaritons into collective molecular states coupled to the cavity photon coherently. We contrast the feature stemming from light emission from the HT polariton state with those that occur due to polariton-enhanced light absorption. Our results demonstrate the landscape of molecular and photonic interactions enabled by cavity polariton formation using complex chromophores and how researchers can design resonators to leverage these interactions to characterize and control polaritonic properties. 

   more » « less
3. Ultracompact 4H-silicon carbide optomechanical resonator with f _m  ·  Q _m exceeding 10 ¹³   Hz

   https://doi.org/10.1364/PRJ.567674  

   Liu, Yuncong; Sun, Wenhan; Abiri, Hamed; Feng, Philip_X-L; Li, Qing (August 2025, Photonics Research)

   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 frequencyf_mof 0.95×10⁹  Hz, a mechanical quality factorQ_mof 1.92×10⁴, and a footprint of <1×10⁻⁵  mm². The correspondingf_m·Q_mproduct 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
4. Effective quality factor tuning mechanisms in micromechanical resonators

   https://doi.org/10.1063/1.5027850  

   Miller, James_M_Lehto; Ansari, Azadeh; Heinz, David_B; Chen, Yunhan; Flader, Ian_B; Shin, Dongsuk_D; Villanueva, L_Guillermo; Kenny, Thomas_W (December 2018, Applied Physics Reviews)

   Quality factor (Q) is an important property of micro- and nano-electromechanical (MEM/NEM) resonators that underlie timing references, frequency sources, atomic force microscopes, gyroscopes, and mass sensors. Various methods have been utilized to tune the effective quality factor of MEM/NEM resonators, including external proportional feedback control, optical pumping, mechanical pumping, thermal-piezoresistive pumping, and parametric pumping. This work reviews these mechanisms and compares the effective Q tuning using a position-proportional and a velocity-proportional force expression. We further clarify the relationship between the mechanical Q, the effective Q, and the thermomechanical noise of a resonator. We finally show that parametric pumping and thermal-piezoresistive pumping enhance the effective Q of a micromechanical resonator by experimentally studying the thermomechanical noise spectrum of a device subjected to both techniques. 

   more » « less
5. High Q‐Factor Polymer Microring Resonators Realized by Versatile Damascene Soft Nanoimprinting Lithography

   https://doi.org/10.1002/adfm.202312229  

   Lin, Wei‐Kuan; Liu, Shuai; Lee, Sungho; Zhang, Zhesheng; Wang, Xueding; Xu, Guan; Guo, L_Jay (January 2024, Advanced Functional Materials)

   Abstract High‐quality‐factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100‐nm critical feature size in the coupling region. In this work, a new method “damascene soft nanoimprinting lithography” is demonstrated that can create high‐fidelity waveguide by simply backfilling an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q‐factor polymer microring resonators (e.g., ≈5 × 10⁵around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q‐factors can be attributed to the residual layer‐free feature and controllable meniscus cross‐section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator. 

   more » « less