Modulight (Finland)

Semiconductor lasers are small and robust devices with low power consumption and good reliability. They can be produced in a wafer scale process yielding up to thousands of devices and a large span of wavelengths can be covered with different structures. Applications, such as Raman spectroscopy with large excitation areas, seed lasers for non-linear frequency conversion and pumping solid state and fiber lasers, require the combination of high output power, narrow emission linewidth operation and good beam quality. The combination of these demanding requirements can be fulfilled using tapered diode lasers with monolithic gratings. Tapered amplifier diodes provide high output powers while maintaining good beam quality. Narrow emission linewidth can be achieved using a wavelength selective distributed Bragg reflector structure (DBR). Using a narrow linewidth DBR laser as a master oscillator (MO) and a tapered amplifier as the power amplifier (PA) enables the combination of high output power, narrow emission linewidth and good beam quality. When these structures are monolithically integrated on a semiconductor chip, the advantages of compact and simple configuration and a scalable process are maintained. The tapered amplifier section amplifies any backward reflected light and couples back to the master oscillator, broadening the emission linewidth. For applications such as atomic physics, this broadening can be eliminated by placing an optical isolator between the master oscillator and power amplifier. In this paper we present key laser characteristics of DBR MOPA lasers produced at Modulight, both as a monolithic structure and as separate components. The fabricated devices operate in the 78xnm region to fit wavelength requirements for Raman spectroscopy (785nm) and rubidium (778nm, 780nm) applications, as well as at 935nm for ytterbium ion repumping. The concept and process can be adapted to the whole emission band available from GaAs based lasers.

The microscopy field has been rapidly developing lately, focusing on enhancing resolution, speed, and versatility within the imaging methods. Among several rapidly developing microscopy techniques is super-resolution microscopy, which enables surpassing of the diffraction limit of light and, thus, gives us access to the details of the biological processes unseen before. Achieving such high resolution requires a laser light engine that meets strict criteria for beam quality, power range, and stability. <br/><br/> This paper focuses on the development of a light engine tailored for super-resolution microscopy, emphasizing its ability to integrate essential specifications for this imaging modality. These include precise center wavelengths with narrow spectral linewidths optimized for specific fluorescent labels. The laser's power output is aimed to be adjustable across a broad dynamic range, from milliwatts to watts, meeting various imaging needs while ensuring sample integrity. Apart from that minimizing laser speckle noise is critical for producing consistent, high-clarity microscope images. <br/><br/> The developed ML6600 microscopy platform has the capability to accommodate up to four wavelengths (355 nm, 405 nm, 488 nm, 532 nm, 561 nm, and 638 nm). The laser light engine is technically characterized to validate its performance in demanding technical application. The characterization of speckle noise demonstrates its effective control to within a few percent, ensuring stable and reliable imaging outcomes. The obtained laser system can be further seamlessly integrated into existing microscopy platforms, advancing capabilities for cutting-edge microscopy imaging.

Advanced-stage ovarian cancer becomes extremely challenging to treat effectively using current surgical and chemotherapy methods due to factors such as peritoneal metastasis, incomplete resection, and drug resistance. While photoimmunotherapy is emerging as a promising option for unresectable metastases, its full potential often goes unrealized due to varying treatment outcomes. This research effort aims to enhance the reliability, safety, and effectiveness of photoimmunotherapy for peritoneal metastases by combining targeted nanotechnology, fluorescence-guided intervention, and a state-of-the-art medical laser system.

Fluorescence-guided intervention can bolster standard therapies by detecting and treating microscopic tumors before lethal recurrence. Tremendous progress in photoimmunotherapy and nanotechnology has been made to treat metastasis. However, many are lost in translation due to heterogeneous treatment effects. Here, we integrate three technological advances in targeted photo-activable multi-agent liposome (TPMAL), fluorescence-guided intervention, and laser endoscopy (ML7710) to improve photoimmunotherapy. TPMAL consists of a nanoliposome chemotherapy labeled with fluorophores for tracking and photosensitizer immunoconjugates for photoimmunotherapy. ML7710 is connected to Modulight Cloud to capture and analyze multispectral emission from TPMAL for fluorescence-guided drug delivery (FGDD) and fluorescence-guided light dosimetry (FGLD) in peritoneal carcinomatosis mouse models. FGDD revealed that TPMAL enhances drug delivery to metastases by 14-fold. ML7710 captured interpatient variability in TPMAL uptake and prompted FGLD in >50% of animals. By combining TPMAL, ML7710, and fluorescence-guided intervention, variation in treatment response was substantially reduced and tumor control improved without side effects.

Personalized medicine is one of the main directions in current cancer care. To support this trend, Modulight has designed a laser illumination platform with real-time spectral monitoring to adjust treatments based on each patient’s optical properties of the tissue, providing more personalization to light-based treatments. The laser has been designed to illuminate and retrieve spectral data from the tumor tissue simultaneously from up to eight different locations. The medical laser is cloud-connected, and all diagnostic data is downloaded in real time into the analytics server to assist in the personalized treatment decisions. This enables machine learning and AI-based data analytics to process recorded data to make more informed treatment decisions and deliver the best treatment outcomes to patients. The laser with this optical monitoring feature is currently being evaluated in glioblastoma trials where illumination can be tailored through spectral monitoring of the fluorescent drug and optical properties of the treated tissue.

Here we present novel cloud-connected theranostic medical laser platform specifically designed for activating and simultaneously monitoring multi-component oncological treatment processes. It may incorporate multiple wavelengths for inducing therapeutic effect or monitoring treatment in real-time. The same low-invasive optical probers can be used for treatment and monitoring. We believe that this theranostic laser platform will allow clinicians to develop improved treatment outcomes for cancer patients that may be based on machine learning and AI in the future.

Vertical-cavity surface-emitting lasers (VCSELs) have recently paved their way into the 3D sensing market, specifically in mobile device applications. Vertical emission of VCSELs enables arranging single emitters into high-power 2D arrays. Thus, VCSEL arrays require efficient heat management which can be implemented by the means of packaging, both to improve thermal conductivity and to keep VCSEL chips intact. This becomes particularly important when considering also very high-density laser arrays and 2D matrices for quantum computing targeting a larger number of parallel outputs. Despite VCSELs decreased temperature sensitivity, their internal efficiency strongly depends on the internal temperature rise, which is defined by the dissipated power and thermal impedance of the laser assembly. Thermal impedance effect is more notable in the proximity to the gain medium, resulting into a drastic temperature gradient due to relatively thick substrate and its poor thermal conductivity. This prevents efficient heat dissipation in the gain media and creates a need for additional heat sinking. In this work, the improved heat sinking is implemented by packaging VCSEL arrays onto AIN sub mounts and subsequently encapsulating them into a thermally conductive and optically transparent epoxy. Thus, the closest proximity of the gain media to the heat sink is established, leading to an enhanced heat flow. Quantitative evaluation of the heat flow is performed by determining thermal resistance, defined as a ratio of the shift rates in the emission spectrum produced by varying pumping current and the heat sink temperature. The evaluation of thermal resistance of the devices with and without epoxy, not reported earlier, is performed to quantitively demonstrate the obtained improvements in the heat flow, efficiency, and output power.

LiDAR sensors have gathered lot of interest in the field of autonomous driving. Still, the offering of mass-produced, small form-factor all-solid-state LiDAR sensors remain scarce. Furthermore, most of the sensor applications are currently designed for short-range (&lt;50 feet) and medium-range (50-300 feet) applications. There’s a requirement for an efficient solution for long range LiDAR sensor that can be used to monitor the road in front of the vehicle. It must be powerful enough to cover long ranges (300 –800 feet) with high enough refresh rate and minimize detection noise while maintaining eye-safety. For these requirements a flash type LiDAR illuminator would be ideal for fast data collection and minimizing the power density. We propose a novel solution for long-range all-solid-state LiDAR application by using a segmented flash illumination and readout concept utilizing state-of-the-art laser diode technology and CMOS imaging at &lt;1μm wavelength. Employing a stack of individually addressable high-power nanostack arrays as the illumination source allows to produce series of 3D flashes, which significantly improves the transverse resolution of the LiDAR, while at the same time mitigating the requirements for the smallest detector pixel size. The design makes it possible to achieve eye-safety even when targeting long ranges with silicon-based detectors. With this approach, the high illumination intensity requirements for the long range can be fulfilled while at the same time maintaining eye-safe operation. Additionally, the design allows for higher refresh rates while the heat management and the power consumption of the system can be minimized.

We report on the EC BRIDLE project, which aims to develop a direct diode laser source (with more than 2kW of output power from a 100μm diameter optical fibre and an efficiency of 40%) for industrial sheet metal cutting applications. The project concepts are explored, from novel tailored diode laser mini-bars to advanced beam combining architectures.