Integrated modal control and beam combining of high power diode laser arrays for the next generation HEL system
Abstract
Integrated modal control and beam combining of high power diode laser arrays for the next generation HEL systemAbstract:The obje"ctive of this proposal is to obtain several hundred Watts, near diffraction-limited power directly from a single high power diode la"ser bar through integrated modal control and beam combining. This revolutionary concept will dramatically increase the brightness of the state-of art high power diode pump module by more than an order-of-magnitude. The proposed modal control and beam combining met"hod is fully integrated in the diode chip and does not require any external optical components and/or phase control, which reduces t""he system SWaP by more than 10X. In addition, it provides for a simpler, more reliable HEL system. The proposed research is revoluti"onary instead of evolutionary because the optical coupling between the laser array elements is based on the distributed feedback from two dimensional photonic crystals. Thisconcept is entirely different from the previously demonstrated evanescent wave/leaking wav"ecoupling or diffraction wave coupling from an external cavity. Due to this unique distributed feedback mechanism, the proposed bea"m combining method is robust against thermal and other nonlinear effects at high powers and provides great array size scalability. I"n addition, the modal control of each laser element in the array is obtained through the transverse Bragg Resonance (TBR) as opposed"" to index guiding. TBR expands the width of single mode diodes, by > 10X, from a few microns to more than one hundred microns and th"us leads to much higher power from each singlemode emitter in the array. There are several key applications of these high brightness diode laser arrays for the next generation HEL systems: 1) These arrays can directly pump fiber and solid-state HELs. Fiber laser"amplifier power is ultimately limited by the brightness of laser diode pumps. Hence, increasing the laser diode brightness will enab""le scaling fiber laser amplifiers above the present 3kW to perhaps > 10kW, resulting in much simpler, lower SWaP HELs. In addition," enhanced brightness will increase the overlap between the pump and signal and thus increase the gain per unit lengthand efficiency for other laser systems; 2) These combined laser diode arrays can be used as thefront-end input for high power fiber amplifiers so that we can eliminate the multiple-stage amplification setup in the current technology and reduce the system cost and complexity; 3) The arrays can be combined using other combining methods to create direct diode KW laser systems. The proposed coherent laser arr"ay is fully integrated without phase modulator or feedback control, provides large array size scalability, and produces high power," high brightness output beam directly from a single laser bar. The successful realization of this transformative research will have" enormous long-term impacts on many emerging fields, such as material processing, remote sensing and communication, and laser weapon""s and radar systems. Our experience in modal control ofbroad-area diode lasers and preliminary results in theoretical analysis, num""erical simulation, and device fabrication will make the proposed program a success.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2017
- Source ID
- N000141712556
Entities
People
- Zhu Lin
Organizations
- Clemson University
- Office of Naval Research
- United States Navy