Jul. 11, 2024
Tunable Light Sources
The optical domain is defined as the region that can be covered by light generated by the interaction of laser beams with nonlinear crystals and covers the range of 190-20,000 nm. The most groundbreaking studies using these wavelengths are conducted in the time domain using femtosecond pulses. Energetic femtosecond pulses are typically produced with Titanium:Sapphire (Ti:Sa) laser amplifiers at 800 nm and Ytterbium (Yb) amplifiers at 1030 nm. Converting these wavelengths into a broad range of tunable wavelengths can be done either by continuum generation or optical parametric amplification, where the continuum is amplified only at the desired and tunable wavelength. Femtosecond Optical Parametric Amplifiers (OPAs) became commercially available in the early 1990s and they are behind experimental spectroscopy techniques like pump-probe, femtosecond stimulated Raman, 2D electronic and vibrational, sum-frequency generation at interfaces, and others. The closely related technique called Optical Parametric Chirped-Pulse Amplification (OPCPA) combines the OPA concept with the Chirped Pulse Amplification (CPA) and enables energy scaling of OPAs beyond their optical damage threshold. OPCPA devices are typically operated at a fixed wavelength and can provide ultrashort pulse durations and extremely high peak power. Both OPAs and OPCPAs benefit from the availability of higher repetition rates from the Yb-based amplifiers used to pump them.
Key Technologies: Femtosecond lasers, optical parametric amplifiers, optical parametric chirped-pulse amplification, pump-probe, Raman spectroscopy
Silicon Photonics and Biomedical Applications
The integration of optics into biomedical applications has revolutionized various fields such as molecular diagnostics, DNA sequencing, and cellular analysis. Imec, a leading research and innovation hub in nanoelectronics and digital technologies, has been at the forefront of developing chip-level integration of optical functionalities - integrated photonics - to enable higher integration density, allowing for more data per area, per time and thus true innovative biomedical solutions. Also, it allows for cost reduction because of wafer-level production, reduced manual assembly and reduced alignment of discrete optical components. Imec's integration photonics platform encompasses a library of components and even includes integrated III-V light sources. the material platform includes both silicon and silicon nitride photonics, broadening the scope of potential biomedical applications. The capabilities of integrated photonics platforms are illustrated by various pioneering projects spanning cytometry, biosensing, optogenetics, retinal imaging via optical coherence tomography, and photoacoustic imaging. The multidisciplinary approach in these projects underscores the versatility and potential impact of on-chip integrated photonics in advancing biomedical sensing and imaging.
Key Technologies: On-chip, integrated photonics, III-V light sources, silicon, silicon nitride, biosensing, optical coherent tomography, cytometry, photoacoustic imaging
Surface-Enhanced Raman Spectroscopy and Diagnostics
In biology, optical imaging has proven to be a major driver of discovery. Raman spectroscopy excels in this realm, offering multiplexed detection that outperforms common fluorescence methods, particularly in complex biological analysis. Its resistance to photobleaching also affords more reliable quantitative data. However, Raman spectroscopy's broader clinical adoption is hampered by the weak intensity of spontaneous signals. Efforts are being made to develop various strategies to amplify Raman sensitivity. Surface-enhanced Raman spectroscopy (SERS) stands out, where the plasmonic enhancement of signals leads to significantly greater detection capabilities. Despite the strides made, there's a vast innovation potential, especially in optimizing the hotspot density within nanoparticles to further boost SERS sensitivity. The frontier of Raman spectroscopy now moves toward the intelligent design of optical components. In this article, we aim to highlight pioneer platforms that scale from single-cell to tissue-level Raman spectroscopy imaging, pushing the envelope of what's achievable in optical imaging. We will delve into these novel design strategies and their transformative impact on Raman methods, opening new vistas in clinical diagnostics and biological research.
Key Technologies: Raman spectroscopy, Surface-enhanced Raman Spectroscopy
Precision Motion in Biological Applications
Ultra-precision motion plays a critical role in enabling advanced photonic approaches for various applications in genomics, assay automation, novel microscopies, and cell characterization. The use of precise motion control systems allows for the accurate manipulation and positioning of samples, which is essential for achieving reliable and reproducible results. Photonic techniques, such as fluorescence microscopy, Raman spectroscopy, and optical tweezers, rely heavily on precise motion control to enable high-resolution imaging, molecular analysis, and the characterization of cellular properties. Extremely fast and precise focusing is essential in genome sequencing, and novel approaches to provide nanometer precise positioning in milliseconds. Digital pathology makes use of high speed XY scanning motion systems to turn glass slides into useful data. In optical coherence tomography, an interferometric imaging technique based on broad band infrared light, nanopositioning stages are required to scan one of the interferometer arms. In all these examples, motion systems with extraordinary speed and precision are prerequisites for developing and advancing new diagnostic and therapeutic approaches.
Key Technologies: Precision control, fluorescence microscopy, Raman spectroscopy, optical tweezers, optical coherence tomography, genomics
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