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Mode-locked Lasers and Their Prospects

Ultrafast optics have been a very rich research field, and today short pulsed laser systems find different applications in areas of fundamental research as well as for medical applications. Ultrafast laser systems are used for time-resolved studies in chemistry, optical frequency metrology, terahertz generation, spectroscopy and microscopy, and optical coherence tomography. The cornerstone of ultrafast optics are the mode-locked lasers, and developments of mode-locked lasers have been a huge research field in itself. In the last few years, mode-locked lasers have moved from just offering a low cost, rugged and compact source of ultrashort pulses to offering state of the art ultrashort pulses.
Mode-locked Lasers and Their ProspectsMode-locked lasers are an extremely promising type of lasers. The usefulness of such a laser system, while perhaps not obvious at first, is immense. The history of mode-locked lasers began after the first demonstration of a continuous wave lasing in 1960: the creation of the first mode-locked laser occurred at Bell Laboratories in New Jersey. The term “mode-locking” refers to the requirement of phase locking many different frequency modes of a laser cavity. This locking has the result of inducing a laser to produce a continuous train of extremely short pulses rather than a continuous wave of light. Mode-locked lasers generate accordingly short pulses of intense coherent light. Laser cavities can support many different frequencies or resonant modes. A train of picosecond or femtosecond pulses can be produced by actively or passively controlling the light in the cavity so that those different resonant modes interfere. The term mode-locking resulted from an interpretation in the frequency domain: in the mode-locked state, several even many axial resonator modes are oscillating with a locked relative phase.
There are several types of lasers which are particularly attractive for mode-locking such as:

  • Solid-state bulk lasers, based on ion-doped crystals or glasses, are today the dominant type of mode-locked lasers. They allow for very short pulses, very high pulse energies and/or average output powers, high or low pulse repetition rates, and high pulse quality;
  • Fiber lasers can also be mode-locked for generating very short pulses with potential setups;
  • For applications in optical fiber communications semiconductor lasers can be built as mode-locked diode lasers;
  • Dye lasers have a broad gain bandwidth, allowing for very short pulses. Such lasers have been largely replaced with solid-state lasers once these were able to deliver similar or better performance.

Optromix is a fiber laser vendor that focuses on the development of single frequency fiber laser systems. We manufacture lasers using our own technologies based on the advanced research work and patents of international R&D team. Laser processes are of high quality, high precision, easily-automated manufacturing solutions that provide repeatability and flexibility.
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