9 research outputs found
Real-time imaging of standing-wave patterns in microresonators
Real-time characterization of microresonator dynamics is important for many applications. In particular, it is critical for near-field sensing and understanding light–matter interactions. Here, we report camera-facilitated imaging and analysis of standing wave patterns in optical ring resonators. The standing wave pattern is generated through bidirectional pumping of a microresonator, and the scattered light from the microresonator is collected by a short-wave infrared (SWIR) camera. The recorded scattering patterns are wavelength dependent, and the scattered intensity exhibits a linear relation with the circulating power within the microresonator. By modulating the relative phase between the two pump waves, we can control the generated standing waves’ movements and characterize the resonator with the SWIR camera. The visualized standing wave enables subwavelength distance measurements of scattering targets with nanometer-level accuracy. This work opens broad avenues for applications in on-chip near-field (bio)sensing, real-time characterization of photonic integrated circuits, and backscattering control in telecom systems
Kerr-Nonlinearity-Induced Mode-Splitting in Optical Microresonators
The Kerr effect in optical microresonators plays an important role for
integrated photonic devices and enables third harmonic generation, four-wave
mixing, and the generation of microresonator-based frequency combs. Here we
experimentally demonstrate that the Kerr nonlinearity can split ultra-high-Q
microresonator resonances for two continuous-wave lasers. The resonance
splitting is induced by self- and cross-phase modulation and
counter-intuitively enables two lasers at different wavelengths to be
simultaneously resonant in the same microresonator mode. We develop a
pump-probe spectroscopy scheme that allows us to measure power dependent
resonance splittings of up to 35 cavity linewidths (corresponding to 52 MHz) at
10 mW of pump power. The required power to split the resonance by one cavity
linewidth is only 286W. In addition, we demonstrate threefold resonance
splitting when taking into account four-wave mixing and two counterpropagating
probe lasers. These Kerr splittings are of interest for applications that
require two resonances at optically controlled offsets, eg. for opto-mechanical
coupling to phonon modes, optical memories, and precisely adjustable spectral
filters