RESUMO
We report the first fast switchable multiwavelength optical parametric oscillator based on aperiodic optical superlattice technology. The constructed aperiodically poled lithium niobate (APPLN) integrates the functionalities of two quasi-phase-matching devices on a chip to work simultaneously as an electro-optic (EO) switchable notch-like filter and a multiline optical parametric downconverter. When such an APPLN is built in a 1064-nm-pumped optical resonator system, we achieve the oscillation of dual signals at 1540 and 1550 nm, for a single signal at 1540 nm, and a single signal at 1550 nm in the system when the 3-cm-long APPLN is driven by 0 V, 354 V, and 805 V, respectively. The switching among the three signal spectra is operationally simple and electro-optically fast. The electro-optically switched signals also feature enhanced power spectral density due to the unique EO gain-spectrum filtering mechanism employed in this work.
RESUMO
We report a unique spectral narrowing and manipulation technique in an optical parametric oscillator (OPO) realized by an integrated periodically poled lithium niobate comprising an optical parametric gain medium sandwiched by two electro-optic polarization-mode converters (EO PMCs). We achieved a manipulation of the gain spectrum of the OPO via EO and/or temperature control of the EO PMCs, in which we obtained single to multiple signal spectral peaks from the OPO with a spectral width reduced by up to 10 times and peak intensity increased by up to 6 times in comparison with the original signal. Fast EO tuning of the narrowed signal spectral peak has also been demonstrated.
RESUMO
All-optical physiology (AOP) manipulates and reports neuronal activities with light, allowing for interrogation of neuronal functional connections with high spatiotemporal resolution. However, contemporary high-speed AOP platforms are limited to single-depth or discrete multi-plane recordings that are not suitable for studying functional connections among densely packed small neurons, such as neurons in Drosophila brains. Here, we constructed a 3D AOP platform by incorporating single-photon point stimulation and two-photon high-speed volumetric recordings with a tunable acoustic gradient-index (TAG) lens. We demonstrated the platform effectiveness by studying the anterior visual pathway (AVP) of Drosophila. We achieved functional observation of spatiotemporal coding and the strengths of calcium-sensitive connections between anterior optic tubercle (AOTU) sub-compartments and >70 tightly assembled 2-µm bulb (BU) microglomeruli in 3D coordinates with a single trial. Our work aids the establishment of in vivo 3D functional connectomes in neuron-dense brain areas.
RESUMO
Optical super-resolution microscopy allows nanoscale imaging of protein molecules in intact biological tissues. However, it is still challenging to perform large volume super-resolution imaging for entire animal organs. Here we develop a single-wavelength Bessel lightsheet method, optimized for refractive-index matching with clarified specimens to overcome the aberrations encountered in imaging thick tissues. Using spontaneous blinking fluorophores to label proteins of interest, we resolve the morphology of most, if not all, dopaminergic neurons in the whole adult brain (3.64 × 107 µm3) of Drosophila melanogaster at the nanometer scale with high imaging speed (436 µm3 per second) for localization. Quantitative single-molecule localization reveals the subcellular distribution of a monoamine transporter protein in the axons of a single, identified serotonergic Dorsal Paired Medial (DPM) neuron. Large datasets are obtained from imaging one brain per day to provide a robust statistical analysis of these imaging data.