Modulation instability initiated high power all-fiber supercontinuum lasers and their applications
Optical fiber technology (Print)
High average power, all-fiber integrated, broadband supercontinuum (SC) sources are demonstrated. Architecture for SC generation using amplified picosecond/nanosecond laser diode (LD) pulses followed by modulation instability (MI) induced pulse breakup is presented and used to demonstrate SC sources from the mid-IR to the visible wavelengths. In addition to the simplicity in implementation, this architecture allows scaling up of the SC average power by increasing the pulse repetition rate and
... e corresponding pump power, while keeping the peak power, and, hence, the spectral extent approximately constant. Using this process, we demonstrate >10 W in a mid-IR SC extending from $0.8 to 4 lm, >5 W in a near IR SC extending from $0.8 to 2.8 lm, and >0.7 W in a visible SC extending from $0.45 to 1.2 lm. SC modulation capability is also demonstrated in a mid-IR SC laser with $3.9 W in an SC extending from $0.8 to 4.3 lm. The entire system and SC output in this case is modulated by a 500 Hz square wave at 50% duty cycle without any external chopping or modulation. We also explore the use of thulium doped fiber amplifier (TDFA) stages for mid-IR SC generation. In addition to the higher pump to signal conversion efficiency demonstrated in TDFAs compared to erbium/ytterbium doped fiber amplifier (EYFA), the shifting of the SC pump from $1.5 to $2 lm is pursued with an attempt to generate a longer extending SC into the mid-IR. We demonstrate $2.5 times higher optical conversion efficiency from pump to SC generation in wavelengths beyond 3.8 lm in the TDFA versus the EYFA based SC systems. The TDFA SC spectrum extends from $1.9 to 4.5 lm with $2.6 W at 50% modulation with a 250 Hz square wave. A variety of applications in defense, health care and metrology are also demonstrated using the SC laser systems presented in this paper.