Commercial Laser Sources Research Articles

Simultaneous Measurements for Tunable Laser Source Linewidth with Homodyne Detection

The linewidth characteristics of a commercial tunable laser source (TLS) are measured experimentally employing self-homodyne detection method. Three linewidths are obtained at different operating wavelengths with two optical fiber delay lengths. It is found that a slightly higher values are obtained with a longer length of the delay fiber. The long of (50 km and 25 km) of single mode fiber SMF is enough to provide delay for the self-homodyne linewidth measurement.

Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process–quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

High Brightness 1.5 μm Pulsed Fiber Laser for Lidar: From Fibers to Systems

In this article, we discuss the designs and performances of narrow-linewidth erbium-ytterbium fiber MOPA for coherent detection lidars. We report on pedestal and multifilament core erbium-ytterbium large mode area fibers specially designed to generate high energy and good beam quality. Pulse energy of 220 μJ with M2 < 1.4 are obtained with all-fiber three amplification stages. An additional amplifier stage generates 600 μJ with M2 < 2.4. We present the first results of pulsed fiber lidar wake vortices detection using a coherent detection lidar. Maturation of this technology leads to compact all-fiber lasers. Several commercial laser sources for lidars are finally described.

New techniques for laser microprocessing of photovoltaic devices based on thin-film a-Si:H

Laser-controlled ablation of individual layers in glass/TCO/thin-film silicon/metal structures is essential for cell isolation and monolithic interconnection in thin-film silicon photovoltaic technologies. More recently, the potential application of laser scribing techniques for the development of photovoltaic matrix position sensors based on a-Si:H has generated much activity, requiring an excellent control in laser-generated patterns obtained by direct material ablation. This work is aimed to determine process parametric windows for a-Si:H thin-film ablation processes using UV ns laser sources in thin-film a-Si:H-based devices. The study is focussed on direct writing techniques using UV sources. We present ablation threshold measurements and process quality assessment using advanced optical microscopy techniques. Moreover only fully commercial laser sources in the ns regime has been used, bearing in mind that thin film based photovoltaic technologies are still demanding further reduction in production costs and, nowadays, ultrafast sources are beyond their scope both for the investment and running cost of those equipments.