Ondax Low-Frequency / THz-Raman™
Determining Layer Properties in 2D Materials
This high‑throughput screening application note presents Ondax’s THz‑Raman™ spectroscopy for determining layer properties in 2D materials, specifically transition metal dichalcogenides (TMDs) like MoSe₂. By accessing low‑frequency/THz Raman peaks associated with inter‑layer shear modes around 18–18.9 cm⁻¹, the technique enables quantitative analysis of layer number, orientation, defects and dopants beyond the reach of conventional Raman and slower AFM/STM methods. Attalon’s compact, plug‑and‑play THz‑Raman™ systems extend traditional Raman into the THz regime, delivering simultaneous chemical and structural characterization, fast non‑destructive measurements and flexible excitation wavelengths for advanced 2D materials characterization and rapid prototyping.
Crystallization Kinetics in Intact Tablets: Transmission-THz-Raman™
This Crystallization Kinetics in Intact Tablets: Transmission‑THz‑Raman™ high‑throughput screening application note presents Ondax’s Transmission Sampling Accessory for the TR‑Probe THz‑Raman™ platform, enabling transmission Raman analysis of coated pharmaceutical tablets. By probing low‑frequency lattice modes (5–200 cm⁻¹), the method tracks fast polymorphic transformations of APIs like ibuprofen in Advil, revealing conversion from amorphous to crystalline forms that is invisible in standard backscatter Raman and undetectable in real time by XRPD or ssNMR. THz‑Raman™ simultaneously provides structural and chemical fingerprint data and distinguishes carbamazepine polymorphs, delivering rapid, non‑destructive polymorphism and crystallization kinetics monitoring.
Quantifying Degree of Crystallinity
This Quantifying Degree of Crystallinity high‑throughput screening application note showcases Ondax’s THz‑Raman™ spectroscopy for measuring residual crystallinity in pharmaceutical formulations. By extending traditional Raman into the THz/low‑frequency regime, crystal lattice modes of acetaminophen in lactose
(1–20% w/w) are detected with a limit of detection of ~1% w/w, outperforming XRPD sensitivity. THz‑Raman™ offers non‑destructive, no sample‑prep analysis, short acquisition times and low instrumentation cost compared with XRPD and ss‑NMR, making it ideal for process development, formulation, stability testing and material characterization. Compact THz‑Raman™ systems and probe accessories enable rapid, routine crystallinity quantification in any lab or process environment.
Structural Change in Polymers
This Structural Changes in Polymers high‑throughput screening application note showcases Ondax's THz‑Raman™ spectroscopy for monitoring High‑Density Polyethylene (HDPE) lamellar thickness and crystallinity. Conventional Raman spectra (200–2000 cm⁻¹) show minimal contrast between annealed HDPE samples, but complete THz‑Raman spectra (−200 to +200 cm⁻¹) reveal clear shifts in longitudinal acoustic modes (LAM) below 150 cm⁻¹ that correlate with long‑range order and mechanical performance. Using a TR‑Micro‑785 THz‑Raman system and versatile TR‑PROBE accessories, the same setup delivers low‑frequency “structural fingerprint” and standard chemical fingerprint measurements for real‑time, non‑destructive polymer process monitoring and HDPE structural analysis.
How THz and THz-Raman Spectroscopy Are Used in Drug Safety, Farming, and Mining
This article reviews how Terahertz (THz) and low-wavenumber Raman (THz‑Raman) spectroscopy support non-destructive analysis in pharmaceuticals, agriculture, and mining. In drug safety, these techniques identify polymorphs, structural changes, isomers, enantiomers, conformers, and glassy states, improving formulation quality and stability. In farming, they measure water content, nutrients, plant stress, disease, and soil quality for precision agriculture and sustainable crop management. In mining, THz methods characterize crystalline and amorphous minerals while assessing composition, refractive index, and permittivity. THz‑Raman™ spectroscopy extends Raman analysis to frequencies near 5 cm⁻¹, enabling molecular and structural insights across diverse field applications with rapid, portable, cost-effective screening.
Low frequency (THz) Raman Spectroscopy - A green and versatile method to probe polymorphism, isomerism and solvent-induced dynamics in Fe-based metal-organic frameworks
Kristina Gjorgjevikj, Esengül Çiftçi, Dominik Blaimer, Timo Manitz, Kerstin Leopold, Simon Krause
DOI: 10.26434/chemrxiv.15000723/v1
This study demonstrates low-frequency (THz-Raman) spectroscopy as a green, versatile method to probe polymorphism, isomerism and solvent‑induced dynamics in Fe‑based metal‑organic frameworks (MOFs). By analysing lattice vibrational modes, the technique distinguishes polymorphs, isoreticular structures and framework isomers, and tracks solvent‑driven structural changes without extensive sample preparation. The work positions THz‑Raman spectroscopy as a powerful, non‑destructive tool for MOF characterization, solid‑state polymorph screening, mechanochemical synthesis monitoring, and structure–dynamics studies in porous materials and functional Fe‑MOF systems.
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The Impact of Terahertz Spectroscopy and Low-Wavenumber Raman Spectroscopy on Pharmaceuticals, Agriculture, and Minerals
This Spectroscopy Online article reviews how terahertz (THz) spectroscopy and low‑wavenumber Raman (THz‑Raman) spectroscopy are transforming the pharmaceutical, agriculture and mineral industries. In pharmaceuticals, these techniques enable multi‑parameter sensing of polymorphs, structural changes and glassy states for robust drug safety and formulation quality control. In agriculture, they support precision farming by assessing soil nutrients, water content, plant stress and crop quality. In minerals, THz and THz‑Raman provide molecular‑level insights for mineral identification, exploration, extraction and processing, driving more efficient, sustainable resource utilization and advanced materials characterization across these sectors.
Wavelength Stabilized Lasers
SureLock™ Single Frequency Stabilized Lasers: Taking Your Lab into the Field
This SureLock™ Single Frequency Stabilized Lasers white paper explains how Ondax’s Volume Holographic Grating (VHG)‑stabilized lasers transform lab‑grade metrology, spectroscopy and bio‑instrumentation into portable, field‑ready systems. PowerLocker® VHGs narrow the laser linewidth to <50 MHz, lock the wavelength within ~0.1 nm and provide passive stabilization over ~60 °C, all in compact TO‑can packages with low power consumption. The paper highlights applications in Raman spectroscopy, portable material and narcotics screening, gesture recognition, robotic navigation and blood‑flow imaging, and compares SureLock™ lasers favorably against dispersive ECL, DFB/DBR and VCSEL technologies for wavelength‑stabilized single‑frequency laser sources.
Volume Holographic Gratings (VHG)
This SureLock™ Single Frequency Stabilized Lasers white paper explains how Ondax’s Volume Holographic Grating (VHG)‑stabilized lasers transform lab‑grade metrology, spectroscopy and bio‑instrumentation into portable, field‑ready systems. PowerLocker® VHGs narrow the laser linewidth to <50 MHz, lock the wavelength within ~0.1 nm and provide passive stabilization over ~60 °C, all in compact TO‑can packages with low power consumption. The paper highlights applications in Raman spectroscopy, portable material and narcotics screening, gesture recognition, robotic navigation and blood‑flow imaging, and compares SureLock™ lasers favorably against dispersive ECL, DFB/DBR and VCSEL technologies for wavelength‑stabilized single‑frequency laser sources.
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VBG
High-performance Wavelength-locked Diode Lasers
Paul Leisher, Kirk Price, Scott Karlsen, David Balsley, Doug Newman, Rob Martinsen and Steve Patterson
Proceedings of SPIE - Proceedings Volume 7198 - 2009 Feb 24
DOI: 10.1117/12.813528
This article presents high‑performance wavelength‑locked diode lasers that use external volumetric Bragg grating (VBG/VHG) optics to deliver narrow linewidth, wavelength‑stable pump sources for Nd:YAG and Er:YAG solid‑state and fiber lasers. The wavelength‑locked diode laser architecture is wavelength‑agnostic (630–2100 nm) and maintains high optical power and conversion efficiency compared with free‑running semiconductor diode lasers. Experimental results for 885 nm microchannel‑cooled bars and 1532 nm Pearl fiber‑coupled modules show <1 nm and <0.2 nm spectral width, respectively, with minimal power penalty, making these diode laser pumps ideal for industrial, medical and scientific high‑brightness laser systems.
Narrow Line Diode Laser Stacks for DPAL Pumping
Tobias Koenning, David Irwin, Dean Stapleton, Rajiv Pandey, Tina Guiney and Steve Patterson
Proceedings of SPIE - Proceedings Volume 8962 - 2014 Feb 25
DOI: 10.1117/12.2044723
This article presents narrow‑line diode laser stacks for DPAL pumping, achieving high‑power, wavelength‑locked operation for rubidium vapor lasers near 780 nm. Using custom volume Bragg gratings (VBG/VHG) and resistive heaters on each bar, the high power diode laser stack reaches 1 kW optical output with 46% electrical‑to‑optical efficiency and a 3 dB spectral width of 0.072 nm at 600 W and 0.083 nm at 1 kW. The design offers precise wavelength tuning over 0.155 nm to match alkali absorption lines, making these high power diode lasers ideal DPAL pump sources for defence and other directed‑energy applications.
Progress in Commercial Wavelength-Stabilized High Brightness Diode Sources Suitable for Pumping Yb-Doped Fiber Lasers
Aaron Brown, Paul Leisher, Geoff Fanning, Scott Lerner, Zhigang Chen, Ling Bao, Mike Grimshaw, Mark DeVito, Kirk Price, Keith Kennedy, Shelly Lin, Mitchell Reynolds, Scott Karlsen, Jay Small, Robert Martinsen, and Jim Haden
Proceedings of SPIE - Proceedings Volume 8039 - 2011 May 26
DOI: 10.1117/12.883194
This article describes commercial wavelength‑stabilized high‑brightness diode sources for pumping Yb‑doped fiber lasers at 976 nm. nLIGHT’s 100 W, 105 µm, 0.17 NA fiber‑coupled Pearl module uses external volume Bragg gratings (VBG/VHG) to achieve a narrow 0.2 nm linewidth and an ultra‑low wavelength‑temperature coefficient below 0.01 nm/°C. The high‑power single‑emitter architecture delivers >90% fiber‑coupling efficiency and ~50% wall‑plug efficiency, the highest reported for a wavelength‑stabilized 100 W / 105 µm diode pump module. These high‑brightness diode laser pumps combine reliability, spectral stability and compact fiber‑coupled packaging, enabling efficient Yb‑fiber laser power scaling and reduced nonlinearities.
Wavelength Locking of High-Power Diode Laser Bars by Volume Bragg Gratings
Yufeng Li, Viorel Negoita, Tobias Barnowski, Stephan Strohmaier, and Georg Treusch
IEEE Photonics Society Summer Topical Meeting Series - 2012 Aug 27
This article investigates wavelength locking of high‑power diode laser bars by volume Bragg gratings (VBGs) through theoretical modeling and experiments. The authors derive a locking condition that links VBG feedback, facet reflectivity and diode material gain, showing how bar smile and emitter alignment impact effective VBG coupling. Experimental results for an 8‑emitter bar around 938–940 nm demonstrate narrow‑band, wavelength‑locked operation with up to 90% of optical power within a 0.3 nm bandwidth, but also reveal reduced output power and lifetime at high VBG reflectivity. The work guides design of wavelength‑stabilized high‑power diode laser bars for multi‑kW pump and direct applications.
