Several promising, growing cancer therapies are phototherapies, where lasers play central role. Examples of such phototherapies where Modulight has invested over many years are photoimmunotherapy (PIT) and photodynamic therapy (PDT). In these therapies, non-thermal lasers are used to activate photosensitive drug precisely in the tumor, causing very few side effects thanks to improved spatio-temporal control of treatment compared to mainstream systemic cancer treatments. However, the field is highly regulated and requires multi-disciplinary, collaborative environment for successful clinical implementation. Laser therapies offer clear set of advantages in both curative and palliative cancer treatments, and some examples will be shown in this presentation. The utilization of clinical laser therapies is growing and about to realize their vast potential in standard cancer care.
The demand for fiber lasers has increased due to widening of application areas and higher power levels. As fiber lasers have become the main workhorse for high power material processing applications and competition among fiber laser manufacturers have become more evident, the laser manufacturers are in the process to find ways to lower overall cost of ownership to become more competitive. Key areas to look at are the efficiency of the fiber laser, especially the efficiency of the diode pump modules, and the higher reliability of its’ components. There is increasing demand for high power, high brightness, and higher efficiency laser diodes for kW-level fiber laser pumping. We present high-efficiency and high brightness laser diode optimized for lowered operating voltage while maintaining high power conversion efficiency of 60%. The laser diode design is a single quantum-well InGaAs/AlGaAs structure with graded index profile and large optical cavity design. The laser is fabricated into 4 mm long chips with a 94 μm emitter stripe indented for standard 105/125 μm core fiber laser pumping. The chips are mounted on AlN carrier and characterized as chip-on-submount. The laser produces 12.6 W optical power at 13 A and 1.62 V, reaching 60% conversion efficiency at operating point. The beam divergence angles are 8.5° horizontal and 34° vertical enabling high brightness and efficient fiber coupling. Furthermore, the lasers are reliability tested where they show outstanding reliability without sudden failures and ware-out rate less than 1% per 1000 hour over several thousand hours of testing.
Visible vertical-cavity surface-emitting lasers (VCSELs) are potential light sources for polymer optical fibre (POF) data transmission systems. Minimum attenuation of light in standard PMMA-POFs occurs at about 650 nm. For POFs of a few tens of meters in length VCSELs at slightly longer wavelengths (670 - 690 nm) are also acceptable. So far, the visible VCSELs have been grown by metal organic chemical vapour deposition (MOCVD). They may also be grown by a novel variant of molecular beam epitaxy (MBE), a so-called all-solid-source MBE or SSMBE. In this paper, we describe growth of the first visible-light VCSELs by SSMBE and present the main results obtained. In particular, we have achieved lasing action at a sub-milliamp cw drive current for a VCSEL having the emission window of 8um in diameter, while a 10um device exhibited an external quantum efficiency of 6.65% in CW operation at room temperature. The lasing action up to temperature of 45°C has been demonstrated.
Monolithic top-emitting resonant cavity light-emitting diodes (RCLEDs) have been fabricated by solid-source MBE. The RCLEDs in the 650-nm range, with modulation bandwidths exceeding 180 MHz, are possible low-cost transmitter candidates for systems using plastic optical fibers (POFs), such as IEEE-1394 at 100 Mb/s and 200 Mb/s and ATM at 155 Mb/s. Modulation bandwidth of greater than 120 MHz and light power of 2 mW (cw) have been achieved for (phi )84-micrometer devices driven at a 40 mA current. Accelerated aging tests for 27,500 device-hours indicate no degradation in output power. A variation in device temperature significantly modifies the far-field pattern and thus the fiber coupling efficiency, due to a cavity detuning effect. The effects of detuning and the temperature and bias dependencies of the devices are investigated. The 880-nm RCLEDs have a maximum output power of 25 mW. Applications include open-air optical communication systems, collision avoidance and measurement systems.
KEYWORDS: Quantum wells, Semiconductor lasers, Cladding, Refractive index, Near field optics, GRIN lenses, Optical simulations, Waveguides, Metalorganic chemical vapor deposition, High power lasers
In the already classical separate confinement (SCH) quantum well (QW) semiconductor laser diode structures many of the desired performances are contradictory coupled through the structural parameters -- i.e. a structural parameter modification leading to the improvement of one or more laser performances will produce the deterioration of at least another performance. Based on an analysis of this contradictory coupling a novel transverse layer structure that alleviates the problem and enables improved laser diode performances is proposed. Both optical simulation and a fully self-consistent model are used in a design optimization methodology and simple evaluation and optimization criteria for the new transverse structure are derived. A number of the analyzed high-power edge-emitting GazIn1-zP/(AlxGa1- x)yIn1-yP/GaAs quantum well laser structures were prepared using all-solid-source molecular beam epitaxy (SS-MBE) for layer growth and remarkable performances were obtained (continuous wave output powers of 3 W at 670 nm, 2 W at 650 nm, and 1 W at 630 nm; threshold current densities of 350 - 450 Angstrom/cm2 for 670 nm, 500 - 540 A/cm2 for 650 nm, and 600 - 680 A/cm2 for 630 nm). Although only a few of the optimization features were implemented the good agreement between measurements and simulations for the prepared structures indicate that significant performance improvements -- predicted by the simulations -- are still possible.
Monolithic top emitting resonant cavity light-emitting diodes operating in the 650 and 880 nm ranges have been prepared using solid-source molecular beam epitaxy growth. Transfer matrix based modeling together with a self- consistent model have been sued to optimize the devices' performances. The design of the layer structure and doping profile was assisted by computer simulations that enabled many device improvements. Among the most significant ones intermediate-composition barrier-reduction layers were introduced in the DBR mirrors for improving the I-V characteristics and the cavity and mirrors were detuned aiming at maximum extraction efficiency. The fabricated devices showed line widths below 15 nm, CW light power output of 8 and 22.5 mW, and external quantum efficiencies of 3 percent and 14.1 percent in the 650 nm and 880 nm ranges, respectively - while the simulations indicate significant performance improvement possibilities.
We report on resonant cavity light-emitting diodes, operating at 660, 880, and 1300 nm wavelengths. Some of the characteristic features of these devices will be discussed. The devices were grown by all-solid-source molecular beam epitaxy (SSMBE). The results provide clear-cut evidence that SSMBE is a viable method to growth of phosphorous containing semiconductors.
This paper presents the performance characteristics and reliability data of AlGaInP-based VISIBLE laser diodes emitting at the wavelengths from 630 to 670 nm. The lasers are grown by toxic gas free solid source molecular beam epitaxy.
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