MPLC-Based OAM Laser Transformer

We propose to demonstrate an OAM transformer based on the multi-plane light conversion (MPLC) technology and wavelength-division multiplexing. Since the pre-release of this SBIR topic, our team has carried out preliminary simulations and experiments to prove the feasibility of the proposed approach by demonstrating Gaussian to OAM (L=1 through 5) transformations using a two-phase-mask MPLCs, with insertion loss < 0.1 dB and mode purity > 15 dB. Furthermore, we have designed an MPLC for converting a Gaussian beam into a superposition of two OAM modes (L=8 and L=9), which is required for the degenerate SAM and non-degenerate OAM four-wave-mixing interaction in ring-core OAM fibers for wavelength translation. This MPLC again uses only two phase masks, yielding an insertion loss <0.2 dB and mode purity >15 dB. During Phase I research, we will 1) Design MPLC phase screens for an OAM mode transformer/multiplexer that can convert 3 Gaussian beams at three wavelengths, 1 micron, 1.5 microns and 2 microns, into 3 desired (superposition of) OAM modes (with LĀbetween ▒5 and ▒40) and multiplexed them into a single ring-core OAM fiber, 2) fabricate and assemble the above MPLCs using lithographically defined phase masks, and 3) in the Option period, partially fulfill Phase II goals by delivering a compact device with two LMA/SMF pigtails carrying 0.98 micron and 1.5 microns of light and produce two desired OAM modes in a ring-core OAM fiber, with one specific OAM mode for each wavelength.