# Fabrication of Smart Materials Using Laser Processing: Analysis and Prospects
## 6 Laser-Processed Smart Materials in Photonics and Optoelectronics
A 0.4-numerical aperture objective was utilized for the focusing of laser beams on the surface and within the sample volume, resulting in a spot size (defined at 1/e\({}^{2}\)) of 1.94 \(\upmu\)m for 1030 nm and 1.6 \(\upmu\)m for 850 nm. Figure 13 depicts the applied spatio-temporal beam engineering techniques, utilizing spatial and spectral phase modulation for shaping beams in both spatial and temporal domains. The study in [171] described the use of ultrafast laser processing to produce multiscale photonic structures in bulk chalcogenide glasses, enhancing their potential for constructing efficient embedded spectrometers and saturable absorbers for integrated photonic applications. A comprehensive structural and optical characterization of germanium antimony selenide (Ge-Sb-Se) films induced by femtosecond laser micromachining was presented  
Figure 12: Partial crystallization by changing laser pulse width. (**a**) Crystal fraction, reflectivity, and transmissivity in response to a pulse with different widths: controlled reflectance as a function of pulse duration is observed. (**b**) Crystallographic microstructures resulting from laser irradiation. Upper row: simulation. Lower row: experiments. Scale bar: 200 nm [168]. Figure 13: Techniques of spatio-temporal beam engineering employing spatial and spectral phase modulation for beam shaping in space and time domains. Examples encompass the creation of non-diffractive beams, parallel processing, beam slit-shaping, and time-envelope shaping [170]. in [172], offering valuable insights for the development of versatile photonic devices. Adjusting laser power and scanning speed during laser direct writing allowed the creation of various regions in chalcogenide films. Additionally, the study in [173] investigated the impact of multiple annealing cycles below the glass transition temperature on the response of bulk sulfur-based chalcogenide glasses to ultrafast laser pulses, emphasizing the potential implications of these findings for improving efficient photo-inscription techniques in integrated photonics. Laser-induced phase transitions, capable of adapting the material's refractive index, enabled dynamic control of light propagation. This technology has been employed in creating reconfigurable photonic circuits, optical switches, and modulators, offering enhanced versatility in optical signal processing. These developments will have wide-ranging applications in future intelligent photonic systems [174]. In the field of optoelectronics, laser-processed smart materials play a vital role in the design of responsive devices. Materials engineered to change their optical properties under laser irradiation can be integrated into optoelectronic components, such as light-emitting diodes (LEDs), displays, and sensors. This allows to create adaptive optoelectronic systems that can dynamically adjust their characteristics based on changing environmental conditions. The study in [175] focused on Ge-Sb-Se-Te (GSST) materials, highlighting their remarkable properties as phase-change materials. The research explored both bulk and thin films of these materials, emphasizing their applications in optoelectronic devices, such as switching, metasurfaces, de-multiplexers, and modulation concepts. One of the most common methods for deposition of chalcogenide thin films is the pulsed laser deposition (PLD) technique [176]. Furthermore, laser micromachining, encompassing techniques like laser ablation and laser etching, is instrumental in the fabrication of intricate photonic structures such as diffraction gratings and optical waveguides directly onto materials, allowing for the tailored design of optical components [177; 178].