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In this presentation, I will discuss about optical measurement of magnetic excitations in different magnetic systems, which is a fascinating branch of the research fields of spintronics and magnonics. The motivation is to optically tune and probe the dynamic magnetic state, at different time and length scales. Two techniques will be discussed, namely time resolved magneto optical Kerr effect spectroscopy and angle resolved Brillouin light scattering spectroscopy (BLS). The former employs ultrashort laser pulses to manipulate the magnetization and subsequently examine it in the pump probe manner. I will show all optical switching of magnetization using femtosecond laser pulses in thin films of ferrimagneticHeusler alloy Mn2RuxGa, which dynamically occurs in ~ 10 ps. The BLS technique, on the other hand, measures the magnonic band structure of magnons, by detecting and analyzing the inelastically scattered light from the magnetic sample. Results of tunable magnonic band structure will be shown in synthetic magnetic metamaterials, namedmagnonic crystals, which are the magnetic counterpart of electronic crystals. Finally, I will discuss on the prospects of attosecond magnetic spectroscopy, which is the fastest optical spectroscopy technique till date. |