The importance of laser beam measurement in the development of ultrafast lasers
Tuesday, September 03, 2019
Generating optical pulses with a duration of less than one trillionth of a second from a laser source has been one of the greatest achievements of mankind recorded in the history of science. While researchers push the limits of ultrafast laser science, measurement devices compatible with such technology are required in order to obtain precise laser beam measurements.
“Ultrafast science is a tool that can be applied to further the understanding of almost every conceivable scientific discipline.”–when Gérard Mourou, the 2018 Nobel Prize laureate in Physics, said this sentence, it was 1992. From that time to onwards, ultrafast science has been used in many different areas and disciplines from medicine to astrophysics and from engineering to material science, and has garnered growing interest. Therefore, Mourou was absolutely right.
Lasers generating extremely short pulses of the orders of picoseconds or femtoseconds have revolutionized many fields of science and engineering, especially in materials processing applications. Today, such lasers have led to the formation of a large economy and of different research areas, with increasing activity in life sciences and industries. There are many variables related to such complex and sensitive systems, and thus it is crucial to use proper laser beam measurement devices during development procedures to obtain a well-functioning system.
Ultrafast laser pulses are generated by a complex laser oscillator which requires precise optical alignment. At every step of the ultrafast laser development, you must be aware that your laser is still “ultrafast” and preserve beam performance. Thus, the characterization of properties of the laser beam including its width, its spatial or intensity distribution and its shape has great importance in the development procedure.
The energy from the oscillator could be from nanojoule to millijoule-level since the repetition rates of such systems are generally at the MHz level. In such high repetition rate laser systems, where the average power from the oscillator is low, it is important to use power meters which can measure low power levels with as low a noise level as possible.
The repetition rate of the laser signal can be reduced after the oscillator, and by using electro-optical components and Hz-level repetition rate, ultrafast pulses can be achieved. In such systems which require high-speed measurements, it is possible to measure the pulse energy of the laser beam directly up to a 1 MHz repetition rate by using well-calibrated laser energy detectors with a low level of uncertainty.
You should also note that, while the repetition rate becomes shorter and the amplification is realized, the peak power of the laser beam might become extremely high, depending on the beam profile. Last but not least, choosing a laser power meter, a laser energy meter or a laser beam diagnostic system to verify the beam profile without ignoring the damage threshold and limits of the measurement product is vital.
The ultrafast laser development process is challenging most of the time and needs your full attention to achieve a robust device. These elegant but delicate systems need not only the best developers but also reliable laser beam measurement devices of cutting-edge technology, as Gentec-EO has been providing for decades.