Solutions Category: Free Space Solutions

Free Space Solutions

Posted on December 12, 2025 by -

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Free Space Up-Conversion

Highly efficient second harmonic generation (SHG) and sum frequency generation….

Free Space Down-Conversion

Waveguide chip and bulk crystals for down -conversion processes including difference frequency generation (DFG), spontaneous parametric down-conversion (SPDC), and optical parametric oscillation/generation/amplification (OPO/OPG/OPA)….

Free Space Up-Conversion

AdvR’s MgO:PPLN, PPLN, and PPKTP waveguide and bulk-crystal free-space up-conversion solutions provide high-efficiency SHG and SFG. A broad range of materials, waveguide types, and custom crystal options enables optimal performance for specific interaction wavelengths and power requirements. These free space solutions ensure reliable, versatile frequency conversion for research and OEM applications.

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Free Space Down-Conversion

AdvR’s MgO:PPLN, PPLN, and PPKTP bulk-crystal and waveguide chip free-space solutions deliver high efficiency wavelength conversion for DFG, OPO/OPG/OPA, and SPDC. With custom grating options and a wide range of materials and waveguide types, these modules provide reliable performance across a broad wavelength range. Available in both in-stock and fully customized configurations.

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Explore our free-space conversion solutions for high-efficiency up-conversion and down-conversion. Get in touch to speak to an expert.

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Relevant Resources

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TECHNICAL GUIDE: Frequency Doubling Femtosecond Fiber Lasers

One of the most common applications of our crystals is for the generation of femtosecond pulses at around 780nm whic……

Technical Guides
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WHITE PAPER: Non-linear Optical Crystals Used for Quantum Te…

Quantum Technology Quantum Technology (QT) is an exciting area of science which is already making a difference to……

Whitepapers
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WHITE PAPER: Wavelength Engineering Using Non-Linear Optical…

Non-linear optical crystals Non-linear optical (NLO) crystals provide an enormously flexible solution for generat……

Whitepapers
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Welcoming Walter Bevers to the Hawthorn Photonics Group

Posted on July 13, 2026 by -

Walter joins us at an exciting stage in our development as we continue to strengthen collaboration across our three specialist businesses, Covesion in the UK, AdvR in the United States and Radiantis in Spain. His appointment marks an important step in bringing our commercial teams together, allowing us to offer customers a connected and coordinated experience while building on the technical expertise that has made each company successful.

As Vice President of Sales, Walter will lead our global sales organization, developing a unified commercial strategy across the Hawthorn Photonics group. He will oversee sales activities across our established markets, including defense, aerospace and scientific instrumentation, while helping us expand our presence in emerging areas such as quantum technologies.

Working closely with our engineering, scientific and marketing teams, Walter will ensure we continue to provide customers with photonics solutions that meet increasingly complex technical requirements. He will also lead the development of common sales processes, reporting systems and commercial best practice to support the group’s continued growth.

Walter brings more than 30 years of experience in the photonics and laser industry. Most recently, he served as Senior Director of International Sales at MKS Instruments, where he was responsible for the global distribution channel for the Newport and Spectra-Physics brands and led direct sales teams across Europe. In addition, he held senior leadership positions at Newport Corporation and Spectra-Physics, building extensive experience in international sales, business development and team leadership. Earlier in his career, he worked in engineering and operations with Philips Lighting and Etap Lighting, giving him a strong technical foundation alongside his commercial expertise. Walter holds a Master’s degree in Physics from the University of Antwerp and a Bachelor’s degree in Business Management from Katholieke Hogeschool Leuven.

Commenting on Walter’s appointment, Mike Day, President of Hawthorn Photonics, said: “Walter has spent his career helping customers solve complex technical challenges and leading international sales organizations in our industry. He understands both the science

behind our technologies and the commercial realities of the markets we serve. As we continue to bring Covesion, AdvR and Radiantis closer together as one group, his experience, leadership and collaborative approach will be instrumental in strengthening our global sales organization and supporting the next phase of our growth. We are delighted to welcome Walter to the Hawthorn Photonics team.”

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AdvR Announces Launch of New Website

Posted on January 23, 2026 by -

We are proud to announce the launch of our new website, www.advr-inc.com. This exciting development reflects our ongoing commitment to enhancing customer engagement and delivering an exceptional online user experience.

The new website will play a crucial role in delivering valuable resources and support for researchers, industry professionals, and academics alike. AdvR continues to prioritize innovation in photonics and looks forward to leveraging its enhanced digital presence to engage with the global community and drive future success. The platform will also strengthen collaboration with Hawthorn Photonics Group partners Covesion and Radiantis, facilitating cross-selling opportunities and highlighting the combined capabilities of the group to provide comprehensive, integrated photonics solutions worldwide.

As a leading researcher and manufacturer of advanced frequency conversion solutions, we are renowned for delivering exceptional customer support within the photonics industry. This dedication has been further reinforced with the launch of this new site, which features an expanded Knowledge Hub. Visitors can access technical guides, white papers, and the latest academic research in photonics and frequency conversion, staying up to date with industry developments while gaining insight into AdvR technologies and the practical applications of our solutions.

“The launch of our new website reflects AdvR’s dedication to providing innovative photonics solutions and exceptional service to our customers,” said Dr. Anjul Loiacono, CEO of AdvR. “Our broad product portfolio and expertise in frequency conversion allow us to offer highly tailored solutions to meet complex experimental and industrial needs. Our new website showcases these capabilities and provides a platform for enhanced engagement with our customers and partners. As the photonics industry continues to evolve, AdvR remains committed to supporting cutting-edge applications such as quantum sensing, advanced imaging, and precision measurement, while delivering outstanding pre- and post-sales support.”

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Free Space Solutions

MgO:PPLN Waveguide Free Space Solutions

MgO:PPLN waveguides designed for OEMs and researchers who require maximum conversion efficiency from a free space solution. …

Fiber coupled solutions

MgO:PPLN Fiber Coupled Custom Solutions

Designed for both OEMs and researchers who require a fully customizable fiber coupled solution with maximum output power and high conversion efficiency….

Free Space Solutions

MgO:PPLN Bulk Crystal Free Space Solutions

MgO:PPLN crystals for OEMs and researchers who require free space solutions with maximum output power and high conversion efficiency….

Hawthorn Photonics Group – Sales Organisation Update

Posted on January 16, 2026 by -

Hawthorn Photonics Group confirms that the sales function across all Group brands is now fully consolidated at the Hawthorn Photonics Group level. This structure applies to Covesion, Radiantis and AdvR, and is designed to deliver a consistent, coordinated and strategically aligned commercial approach across the Group’s global operations.

Under this model, all customer-facing sales activities are managed centrally by the Hawthorn Photonics Group sales organisation, while each brand continues to operate as a centre of technical excellence within its respective market segment.

This change reinforces the Group’s integrated operating model and provides a single, consistent point of contact for customers and partners across the Hawthorn Photonics portfolio.

Hawthorn Photonics Group remains focused on delivering operational clarity, commercial efficiency and long-term value to its customers through a unified sales organisation and a strong portfolio of differentiated photonics technologies.

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Free Space Solutions

MgO:PPLN Waveguide Free Space Solutions

MgO:PPLN waveguides designed for OEMs and researchers who require maximum conversion efficiency from a free space solution. …

Fiber coupled solutions

MgO:PPLN Fiber Coupled Custom Solutions

Designed for both OEMs and researchers who require a fully customizable fiber coupled solution with maximum output power and high conversion efficiency….

Free Space Solutions

MgO:PPLN Bulk Crystal Free Space Solutions

MgO:PPLN crystals for OEMs and researchers who require free space solutions with maximum output power and high conversion efficiency….

Continuous wave tunable laser from 616 nm to 637 nm

Posted on January 9, 2026 by -

Ruizhe Gu, Dia Darwich, Germain Guiraud, Mathieu Chauvet, Coline Mahob, Christof Janssen, Giorgio Santarelli, and Adèle Hilico

Abstract

We report on a compact sum frequency generation (SFG) setup generating continuously tunable single-frequency visible radiation from 616 nm to 637 nm, starting from two tunable laser sources at 1 µm and 1.5 µm. We compare two types of crystals: periodically poled lithium niobate (PPLN) and periodically poled magnesium oxide-doped lithium niobate (PPMgOLN), both custom-made such that the tunability range is achieved via temperature control only. We achieve a Watt level of power over the entire tunability range in PPMgOLN, with a mode profile enabling 80% coupling efficiency in a single-mode fiber, limited by the IR sources’ tunability, while keeping the system easy to operate.

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Synchronous mode-locking of solid-state lasers

Posted on January 9, 2026 by -

O. B. Jensen, A. K. Hansen, M. Chi, and P. Tidemand-Lichtenberg

Abstract

This Letter introduces a novel, to the best of our knowledge, method for achieving mode-locking and synchronization of mode-locked output pulses from two lasers. The proposed technique leverages parametric gain from difference frequency generation. Specifically, a Nd:YAG laser is mode-locked by single-pass mode-locked pulses from a mode-locked Ti:sapphire laser using an intracavity nonlinear crystal. When the continuous-wave laser is not actively pumped, the system functions as a synchronously pumped optical parametric oscillator. This novel approach has the potential to enable new devices, especially for pump-probe applications or for generation of mode-locked pulses in spectral regions where conventional mode-locked devices are typically not available.

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Unidirectional ring laser operation and tunable single-frequency emission

Posted on January 9, 2026 by -

O. B. Jensen, M. Helmark, A. G. Urskov, and P. Tidemand-Lichtenberg

Abstract

In this Letter, a novel approach for unidirectional operation of a 1064 nm solid-state ring laser is demonstrated based on difference frequency mixing. Unidirectional operation is achieved exploiting the directional parametric gain from a single-pass diode laser, facilitated through a periodically poled LiNbO3 crystal. In addition to achieving unidirectional operation, the nonlinear process further enables the generation of single-frequency mid-infrared light. Using a single-pass tapered diode laser, tunable in the range from 780 to 815 nm, the generated mid-infrared signal covers the 2.9 to 3.5 µm range while optimizing the phase-match condition of the difference frequency generation process.

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Open-path methane sensing via backscattered light

Posted on January 9, 2026 by -

Jinghan Dong, Weijie Nie, Arthur C. Cardoso, Haichen Zhou, Jingrui Zhang, John G. Rarity, Alex S. Clark

Abstract

Nonlinear interferometry has widespread applications in sensing, spectroscopy, and imaging. However, most implementations require highly reflective mirrors and precise optical alignment, drastically reducing their versatility and usability in outdoor applications. This work is based on stimulated parametric downconversion, demonstrating methane absorption spectroscopy in the mid-infrared (MIR) region by detecting near-infrared photons using a silicon-based CMOS camera. The MIR light, used to probe methane, is diffusely backscattered from a Lambertian surface, experiencing significant transmission loss. We implement a single-mode confocal illumination and collection scheme, using a two-lens system to mode-match the interfering beams to achieve background methane detection at a distance of 4.6 m under a 57 dB loss. Our method is also extended to real-world surfaces, such as glass, brushed metal, and a leaf, showing robust background methane sensing with various target materials.

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Spectral characterization of SPDC-based single-photon sources for quantum key distribution

Posted on December 8, 2025 by -

Sabine Euler, Erik Fitzke, Oleg Nikiforov, Daniel Hofmann, Till Dolejsky & Thomas Walther

Abstract

In our laboratory, we employ two biphoton sources for quantum key distribution. The first is based on cw parametric down-conversion of photons at 404 nm in PPKTP waveguide chips, while the second is based on the pulsed parametric down-conversion of 775 nm photons in PPLN waveguides. The spectral characterization is important for the determination of certain side-channel attacks. A Hong-Ou-Mandel experiment employing the first photon source revealed a complex structure of the common Hong-Ou-Mandel dip. By measuring the spectra of the single photons at 808 nm, we were able to associate these structures to the superposition of different transverse modes of the pump photons in our waveguide chips. The pulsed source was characterized by means of single-photon spectra measured by a sensitive spectrum analyzer as well as dispersion-based measurements. Finally, we also describe Hong-Ou-Mandel experiments using the photons from the second source.

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Photon Pair Source based on PPLN-Waveguides for Entangled Two-Photon Absorption

Posted on December 8, 2025 by -

Tobias Bernd Gäbler, Patrick Hendra, Nitish Jain, Markus Gräfe

Abstract

Fluorescence excitation by absorption of entangled photon pairs offers benefits compared to classical imaging techniques, such as the attainment of higher signal levels at low excitation power while simultaneously mitigating phototoxicity. However, current entangled photon pair sources are unreliable for fluorescence detection. In order to address this limitation, there is a need for ultra-bright entangled photon pair sources. Among the potential solutions, sources utilizing nonlinear waveguides emerge as promising candidates to facilitate fluorescence excitation through entangled photons. In this paper, a source consisting of a periodically poled lithium niobate waveguide is developed and its key characteristics are analyzed. To demonstrate its suitability as key component for imaging experiments, the entangled two-photon absorption behavior of Cadmium Selenide Zinc Sulfide quantum dot solutions is experimentally investigated.

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