A mid-infrared cascading fiber amplifier and method for amplification thereof

In a mid-infrared cascading fiber amplifier device having a source configured to generate a first electromagnetic wave output at a first frequency, a fiber coupled to the source and a pump coupled to the fiber and configured to generate a second electromagnetic wave output at a second frequency, wherein the second frequency is higher than the first frequency and causes the fiber to undergo two or more transitions in response to stimulation by the first electromagnetic wave output at the first frequency, wherein the first transition generates the first electromagnetic wave output approximately at the first frequency and the second transition generates the first electromagnetic wave output approximately at the first frequency, wherein the fiber comprises Pr3+-doped chalcogenide fiber, the pump comprises a backward pump source, the first frequency generates a first wavelength that ranges from approximately 4 to approximately 5 micrometers, the second frequency generates a second wavelength that ranges from approximately 1.90 to approximately 2.3 micrometers, the mid-infrared cascading fiber laser device having a semiconductor saturable absorber mirror and a graphene nonlinear optical saturable absorber, a method comprising:

• generating an input signal wave having approximately the first wavelength and providing the input signal wave to the fiber that is configured to transition from an upper energy level to an intermediate energy level to generate a first output having a wavelength of approximately the first wavelength and the transition from the intermediate energy level to a lower energy level to generate a second output having approximately the first wavelength in response to the input signal wave;
• pumping the fiber with a pump wave having approximately the second wavelength, to cause a transition from the first energy level to the second energy level, and to output an output wave in response thereto, the output wave having approximately the first wavelength;
• wherein generating the input signal wave having approximately the first wavelength and providing the input signal wave to the fiber comprises providing the input signal wave to a Pr3+-doped chalcogenide fiber;
• appending a semiconductor saturable absorber mirror to the fiber;
• appending a nonlinear optical saturable absorber to the fiber;
• and
• appending a graphene nonlinear optical saturable absorber to the fiber.