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Thermal effect of semiconductor lasers is the biggest challenge to the development of semiconductor lasers. This problem limits the life and performance of high‐power laser diode. In this letter, we have reduced the thermal resistance of laser to enhance its heat dissipation capability. For this, we choose aluminium nitride (AlN) to replace traditional materials as insulating layer, as well as a passivation film for facet coating. The impact of insulation layer and facet coating on the thermal rollover process is analyzed. Finite element method simulations are compared with the experimental result. The comparison shows that the thermal resistance of the laser with the new insulating layer is reduced compared with normal laser diodes (LD). Eventually, the maximum conversion efficiency is 67.5% at room temperature and thermal resistance is 1.81C° W–1.

Quantum-cascade lasers (QCLs) based on InGaAs/AlInAs/InP with reflective and antireflective coatings are fabricated and studied. The manufactured lasers emit in the spectral range from 4 to 5 μm. The effect of variation in the front mirror reflectance on the output power of a QCL with a highly reflective rear mirror is investigated. It is shown that the use of an antireflective coating on the front face leads to a simultaneous increase in both the threshold current of the QCL and the slope of the light–current characteristic. This allows a higher output power to be achieved at high pump currents. In contrast, the use of a partially reflective coating on the front face not only reduces the threshold current of the QCL, but also decreases the slope of the light–current characteristic. Such QCLs may have an advantage over other emitters at low pump currents.

Optical coatings are thin layers of materials applied to optical components in order to modify the transmission, reflection, or polarization properties of light. The common materials used for optical coatings include magnesium fluoride (MgF2), scandium trifluoride (ScF3), and aluminum trifluoride (AlF3), owing to their desirable optical properties, spectral range, and compatibility with substrates. However, each of these materials has its own drawbacks. For instance, AlF3 has been found to exhibit limited resistance to attack by chemicals, as well as poor thermal stability, while MgF2 has low durability, as well as being hygroscopic. In this study, we undertook ab initio calculations in order to compare the thermal properties of AlF3, ScF3, Al0.5Sc0.5F3, and In0.5Sc0.5F3 in order to obtain the best material for optical coatings. MgF2 was also included in the study as a reference. The calculations used PBE pseudopotentials and the extended generalized gradient approximation within the quantum espresso algorithm. The study demonstrated that the computed results agree with the information found in the literature. ScF3 exhibited a negative coefficient of thermal expansion, unlike the other four. Moreover, AlF3 was found to be the best candidate for optical coatings that are used in high-power laser systems with high thermal dissipation, due to its superior thermal expansion coefficient as well as its better response to thermal stress. The large variation between the cp and cv of ScF3 is not desirable. Moreover, due to its negative thermal expansion coefficient, ScF3 is not thermally stable. The highest thermal stability was exhibited by In0.5Sc0.5F3. Since Al0.5Sc0.5F3 and In0.5Sc0.5F3 have been modeled in this study for the first time, experimental determination of their crystal structures needs to be investigated.

This study analyses the impact of laser energy on assessing the unique performance of optical coatings made from thin films of mixed (CeO 2 -CaF 2 ) materials with a high refractive index contrast. Additionally, it determines the parameters that influence the selection of thin film for producing optical coatings with novel performance properties and employing a pulsed laser deposition (PLD) technique utilizing Nd-YAG laser with a wavelength of 1064 nm and varying laser energy (500, 600, 700, and 800) mJ while maintaining a constant number of (400) shots. Results demonstrate that at 500 mJ, the optical properties and morphology of the (CeO 2 :CaF 2 ) thin layer are suitable for optical coating applications. Exceptional optical properties were attained, characterized by a refractive index approach of 1.33, enabling the fabrication of a unique optical performance for wideband single-layer antireflection coatings. The Atomic Force Microscopy (AFM) results of different revealed that the average diameters associated with laser energies of 500, 600, 700, and 800 mJ are 34.2, 40.9, 43.6, and 54.07 nm, respectively, and that an increase in laser energy corresponded with an increase in surface roughness. The X-ray diffraction (XRD) analysis and Field Emission Scanning Electron Microscopy (FESEM) of the optimal sample for optical coating at energy 500 mJ indicated that the structure is polycrystalline. Meanwhile, FESEM suggests that this sample is characterized by a nanoscale grain size of approximately 30 nm and enhanced surface uniformity. The study compares experimental and theoretical optical performance reflection (R) results for sample 500 mJ. The theoretical results were based on characteristic matrix theory and MATLAB software.

We present here an optimized design of optical coating antireflection, bandpass, and edge filters in the wavelength range (6000–12,000 nm.) covering the long wavelength infrared range of the spectrum (LWIR). These designs are based on a refinement of a quarter-wave stack, for multilayers of ZnSe/Ge stacks. The results show that the structures and chosen adjusted for the preparation layers stacks are feasible film structures, and in fact, they can be prepared relatively easily. Also, results demonstrate new design constructions with advanced performance agree with desired performance of each type of filter.

Yttrium nitride (YN) is a hard and refractory material with a high melting point. It is a semiconductor that has been investigated for its potential applications in the field of semiconductor technology, including as a material for electronic devices. It is also of interest for its optical properties and its potential for use in optoelectronics. However, investigating its mechanical properties for a possible application in optical coatings has not been completed. This study involved the exploration of the mechanical properties of YN alloyed with niobium (Nb) and zirconium (Zr) for possible application in optical coatings using a first-principles approach. The result showed that the addition of Nb and Zr into the YN matrix had a profound effect on the mechanical properties of the modeled structures, with the Y-N-Nb (CYN_5) sample having the best mechanical properties. The bulk modulus was the most affected, with an increase of 26.48%, while the Vickers hardness had the smallest increase of 6.128% compared with those of pure YN. The modeled structures were thus found to be ideal alternative materials for optical coatings due to their improved mechanical properties.

In modern optical coating production, optical monitoring technology is an indispensable component. The traditional monochromatic monitoring technology used in current commercial and research institutions is usually only for a specific wavelength and cannot fully represent the characteristics of the film in the entire spectral range. Moreover, for non-quarter-wave coating systems (such as multilayer or complex coating systems), a thickness change in a single coating may have a significant effect on the performance of the entire coating system. In this case, it may be difficult to use monochromatic monitoring to accurately determine the thickness of each layer, resulting in reduced monitoring accuracy. At present, although broadband optical monitoring can be monitored over a wide wavelength range, the stop-plating time may be misjudged due to error accumulation during the coating process. To solve these problems, a broadband optical monitoring method with an improved error compensation mechanism is proposed in this paper. An optimal function that combines the absolute error and shape similarity of the transmission spectrum is designed, and the transmission spectrum is optimized by the limited random search method. In addition, a breakpoint algorithm based on parabolic error curve prediction is designed for the first time in this paper, which avoids the problem of excessive deposition thickness encountered by traditional broadband monitoring methods in the automatic coating processes. To verify the effectiveness of the proposed method, a set of hardware verification platforms based on broadband optical monitoring is designed in this paper, and a 30-layer shortwave-pass filter is constructed as an example. Compared with the traditional time monitoring method (CTMM), the proposed broadband optical monitoring method (PBMM) has significant advantages in terms of the matching degree between the transmission spectrum and the target spectrum, as well as the average transmittance in the low-pass band. In summary, the broadband optical monitoring method with an improved error compensation mechanism proposed in this paper provides an effective solution for high-precision optical coating production and has high practical application value and research significance.

We consider an algorithm for monitoring the process of sputter deposition of optical coatings based on the analysis of sample data of broadband measurements for a fixed set of wavelengths. On the one hand, the considered algorithm uses broadband measurement data, which is an advantage compared to using only monochromatic measurement data for one fixed wavelength, and on the other hand, it is fast compared to algorithms that use complete broadband measurement data. It has been demonstrated that the proposed algorithm allows one to obtain fairly accurate estimates of the layer thicknesses in deposited multilayer optical coatings.

Optical coatings usually consist of many multilayers of thin films to achieve the desired properties. A new approach using interference effects between an absorbing dielectric film and a metallic substrate now enables ultrathin optical coatings that could also find applications as thin solar cells or photodetectors. Optical coatings, which consist of one or more films of dielectric or metallic materials, are widely used in applications ranging from mirrors to eyeglasses and photography lenses 1 , 2 . Many conventional dielectric coatings rely on Fabry–Perot-type interference, involving multiple optical passes through transparent layers with thicknesses of the order of the wavelength to achieve functionalities such as anti-reflection, high-reflection and dichroism. Highly absorbing dielectrics are typically not used because it is generally accepted that light propagation through such media destroys interference effects. We show that under appropriate conditions interference can instead persist in ultrathin, highly absorbing films of a few to tens of nanometres in thickness, and demonstrate a new type of optical coating comprising such a film on a metallic substrate, which selectively absorbs various frequency ranges of the incident light. These coatings have a low sensitivity to the angle of incidence and require minimal amounts of absorbing material that can be as thin as 5–20 nm for visible light. This technology has the potential for a variety of applications from ultrathin photodetectors and solar cells to optical filters, to labelling, and even the visual arts and jewellery.

Thermally induced fluctuations impose a fundamental limit on precision measurement. In optical interferometry, the current bounds of stability and sensitivity are dictated by the excess mechanical damping of the high-reflectivity coatings that comprise the cavity end mirrors. Over the last decade, the dissipation of these amorphous multilayer reflectors has at best been reduced by a factor of two. Here, we demonstrate a new paradigm in optical coating technology based on direct-bonded monocrystalline multilayers, which exhibit both intrinsically low mechanical loss and high optical quality. Employing these ‘crystalline coatings’ as end mirrors in a Fabry–Pérot cavity, we obtain a finesse of 150,000. More importantly, at room temperature, we observe a thermally limited noise floor consistent with a tenfold reduction in mechanical damping when compared with the best dielectric multilayers. These results pave the way for the next generation of ultra-sensitive interferometers, as well as for new levels of laser stability. By employing monocrystalline semiconductor materials as high-quality optical coatings, the long-standing challenge of minimizing the optical phase noise produced by Brownian motion in a multilayer has been overcome. A thermally limited noise floor consistent with a tenfold reduction in mechanical damping relative to that in the best dielectric multilayers is achieved.