Kilometre-scale, kilowatt average power, single-mode laser delivery through hollow core fibre: overcoming nonlinear limits of glass fibre

High power laser delivery with near-diffraction-limited beam quality, widely used in industry for precision manufacturing, is typically limited to tens of metres distances by nonlinearity-induced spectral broadening inside the glass-core delivery fibres. Anti-resonant hollow-core fibres offer not only orders-of-magnitude lower non-linearity, but also loss and modal purity comparable to conventional beam-delivery fibres. Using a single-mode hollow-core nested anti-resonant nodeless fibre (NANF) with 0.74-dB/km loss, we demonstrate delivery of 1 kW of near-diffraction-limited continuous wave laser light over an unprecedented 1-km distance, with a total throughput efficiency of ~80%. From simulations, more than one order of magnitude further improvement in transmitted power or length should be possible in such air-filled fibres, and considerably more if the core is evacuated. This paves the way to multi-kilometre, kW-scale power delivery – not only for future manufacturing and subsurface drilling, but also for new scientific possibilities in sensing, particle acceleration and gravitational wave detection.

Prediction of life time of high-power IR laser diode by resolution of its spectrum to single-mode components

The paper proposes a method for predicting the service life of high-power laser diodes used in optoelectronic measuring systems which allow adjusting the thermophysical parameters of the diagnosed flow volume in a certain range of their values. The method based on the analysis of the current dependence of the shape of the line enveloping the laser radiation spectrum after 200 hours of their operation. It is shown that for such an analysis the emission spectrum must be considered as a superposition of the emission spectra of single-mode laser diodes.

A Stable 1550nm WGM Laser Generated by Yb3+/Er3+ Co-doped Silica Microspheres under μm ASE Source Pumping

The amplified spontaneous emission (ASE) light source at 1 μm was used to excite Yb3+/Er3+ co-doped silica (YEDS) microspheres by evanescent-wave coupling through a taper optical fiber (TOF) to generate a stable 1550 nm laser. Inevitably, the experimental process was accompanied by a frequency up-conversion luminescence whose fluorescence spectrum was collected and analyzed. Pumped by the ASE light source with different power, the system of YEDS microsphere and TOF also generated single-mode laser and multi-longitudinal mode laser. Their peak wavelength, output power of the peak laser, full width at half maximum (FWHM), and side mode suppression ratio (SMSR) were respectively measured. Moreover, the characteristics of a 1550 nm whispering gallery mode (WGM) laser excited by a 1 μm ASE pumping and a tunable laser (TLS) pumping were compared under different variable conditions. It was demonstrated that the ASE pump source has polarization in all directions to excite WGMs in the microsphere cavity, which was different from and superior to the TLS. Therefore, the laser generated by the ASE pump source as an excitation source was not affected by vibration and temperature change. The results show that the 1550 nm laser pumped by ASE can stably output the microsphere WGM mode laser under the interference of vibration and temperature change, which is more suitable for the actual application environment.

Polarization stability of the single-mode laser diodes radiation applied in radiation scattering study complexes

Key features of semiconductor lasers and its serially manufacturing technology modernization have greatly expanded of its using at applied studies at last 20 years. But there is set of factors restricting such lasers application in a number of optical-electronic measuring complexes. Particularly in particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) complexes commonly the gas and solid-state lasers is used due to more stability of spectral, energy and polarization characteristics of radiation then semiconductor lasers have. However gradual introduction of the serially manufacturing laser diodes into such systems picking up the pace that certainly characterizes the progress of reaching the required stability of its output laser radiation parameters. In laser measurement systems where medium investigation carried out by analyzing of scattering radiation in it the probe radiation polarization is often important. So the using in such systems the laser diodes as sources of radiation need to be followed by stability monitoring of its polarization characteristics which may be violated both by the outer factors and by natural degradation of inner laser diode structure. This work is devoted to the issues of monitoring the radiation polarization characteristics of the serially manufacturing single-mode laser diodes.

Optimization of power supply mode of single-mode laser diode by ratio of current and integral spectrum parameter

Bursting development of the technological base of semiconductor quantum electronics determined the width of the domain for use of semiconductor lasers in optical-electronic measuring systems based on the optical methods of stream research. In order to improve the accuracy of such systems, it is proposed to use a simple technique for optimizing the supply mode of a single-mode laser diode, based on an analysis of the current dependence of its integral spectral parameter. It is shown that the optimal value of the pumping current appears when the radiation spectrum envelope line tends to match the normalized Gaussian curve within the width of the spectral line.

Photonic skins based on flexible organic microlaser arrays

Flexible photonics is rapidly emerging as a promising platform for artificial smart skins to imitate or extend the capabilities of human skins. Organic material systems provide a promising avenue to directly fabricate large-scale flexible device units; however, the versatile fabrication of all-organic integrated devices with desired photonic functionalities remains a great challenge. Here, we develop an effective technique for the mass processing of organic microlaser arrays, which act as sensing units, on the chip of photonic skins. With a bilayer electron-beam direct writing method, we fabricated flexible mechanical sensor networks composed of coupled-cavity single-mode laser sources on pliable polymer substrates. These microlaser-based mechanical sensor chips were subsequently used to recognize hand gestures, showing great potential for artificial skin applications. This work represents a substantial advance toward scalable construction of high-performance and low-cost flexible photonic chips, thus paving the way for the implementation of smart photonic skins into practical applications.