All-optical-fibre mode-locked laser based on Kerr effect of multi-mode interference device

Abstract

The invention discloses an all-optical-fibre mode-locked laser based on the Kerr effect of a multi-mode interference device; a pumping source emits an active optical fibre to absorb pump light in a band; after being coupled through a signal pumping beam combiner, the pump light enters the active optical fibre; the active optical fibre absorbs the pump light to form population inversion, so that laser gain is generated; the multi-mode interference device is formed by welding a section of multi-mode optical fibre in the middle of two sections of single-mode optical fibres; the transmission peak of the multi-mode optical fibre is the same to the gain peak of the active optical fibre; the signal pumping beam combiner, the active optical fibre, the multi-mode interference device, an output coupler and an isolator are in fusion welding in sequence, so that a one-way annular laser resonant cavity is formed; under the action of laser, the refractive index of the multi-mode optical fibre is changed; furthermore, the position of a multi-mode interference self-imaging point is changed; the transmittance of the multi-mode optical fibre at the position of laser wavelength is changed, so that the laser intensity of the annular laser resonant cavity is modulated; and the output coupler outputs ultra-short pulse laser. The all-optical-fibre mode-locked laser based on the Kerr effect of the multi-mode interference device disclosed by the invention is high in laser output power and low in cost.

Description

technical field [0001] The invention relates to the field of lasers, in particular to an all-fiber mode-locked laser based on the Kerr effect of a multi-mode interference device. Background technique [0002] Ultrafast mode-locked lasers are widely used in basic research, medicine, defense and industrial processing. Due to the many advantages of fiber lasers such as compact structure, high efficiency, robustness, and high cost performance, various stable and compact mode-locked fiber lasers have been developed. Compared with active mode-locking, passive mode-locked fiber lasers have obvious advantages in many aspects. For example, the response and recovery time of saturable absorbers or Kerr-type devices are generally very short, so the pulse width generated by passive mode-locking Usually narrower than active mode-locking; no spatial light modulator and corresponding electronics are required, so the structure is simpler and more compact; and it is not affected by electrica...

AI Technical Summary

Problems solved by technology

An obvious disadvantage of such passively mode-locked fiber lasers is that the saturable absorbing devices used, such as semiconductor saturable absorbing mirrors (SESAMs), carbon nanotubes, and graphene, generally have low damage thresholds and are therefore capable of producing average output The power is limited to the order of several to tens of mW, and the higher power mode-locked pulse laser can only be obtained by fiber amplifiers, which increases the complexity of the system

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