Fiber Laser Modulation for Rectangular Pulse Generation

The patent applies preliminary action by introducing a pre-pump phase before the main pump phase. During this pre-pump phase, the pump light intensity is gradually increased to a predetermined level before reaching the final high power level. This gradual preparation prevents the sudden surge pulse that would otherwise occur at the beginning of the pulse rise time, while still maintaining efficient pulsed light generation.

The patent segments the pump light input into four distinct phases: pre-pump phase, pump phase, light output phase, and light termination phase. Each phase has specific duration and power level characteristics. This segmentation allows precise control over the output waveform, enabling the generation of rectangular pulsed light that does not follow surge pulse, thereby achieving both high illumination intensity and waveform accuracy.

The patent replaces the conventional YAG laser mechanical optical system with a fiber laser system. The fiber laser uses optical fibers as the gain medium instead of solid-state YAG crystals, eliminating the need for complex optical components such as mirrors, lenses, and flash lamps. This substitution maintains the laser marking capability while significantly reducing device size and improving maintainability.

The patent uses parameter changes by adjusting the pump light wavelength and duration to excite specific rare-earth elements (such as Nd³⁺, Er³⁺, or Tm³⁺) doped in the optical fiber. By changing the pump parameters, the fiber laser can generate different wavelengths including green light (around 532 nm through frequency doubling or 560 nm directly), thereby achieving practical green light source implementation that complements the existing red and blue semiconductor lasers.