Index-antiguided waveguide lasers
Category: laser and resonator, quantum electronics, waveguide and fiber optoelectronic devices, photonic crystals, Bragg fibers.
Application: high-power laser, high-energy laser, large-mode-area laser
Gain-guided and Index-antiguided waveguide lasers support leaky modes that exhibit very different resonator characteristics from their conventional index-guided counterparts. For one thing, the large modal differential loss in IAG waveguides enables strong mode discrimination that favors single transverse mode (STM) operation, even for waveguide with very large mode area (LMA). This property lends itself as a promising platform for high-power or high-efficiency lasers. For another, resonator modes in open waveguides such as IAG waveguides in known to exhibit excess quantum noise, a property that could be exploited to yield lasers with controlled coherence properties.
Our group design and fabricate photonic bandgap fibers to achieve STM and LMA for laser radiation while simultaneously strong confinement of pump radiation. We also made the world-first demonstration of continuous-wave GG+IAG planar waveguide laser, fabricated using diffusion bonding by Northrop Grumman Synoptics in Charlotte.
Selected publication (see Publication for complete list)
- Tsinghua Her, “Gain-guiding in transverse grating waveguides for large modal area laser amplifiers,” Optics Express 16 (10) 7197-7202 (2008).
- Tsing-Hua Her, Xianyu Ao, and Lee W. Casperson, “Gain saturation in gain-guided slab waveguides with large-index antiguiding,” Optics Letters 34 (16) 2411-2413 (2009).
- Xianyu Ao, Tsing-Hua Her, and Lee W. Casperson, “Gain guiding in large-core Bragg fibers,” Optics Express 17 (25) 22666-22672 (2009).
- Chaofan Wang, Tsing-Hua Her, Lei Zhao, Xianyu Ao, Lee Casperson, Chih-Hsien Lai, Hung-Chun Chang, “Gain Saturation and Output Characteristics of Index-Antiguided Planar Waveguide Amplifiers with Homogeneous Broadening,” Journal of Lightwave Technology 29, p. 1958 (2011).
- Chaofan Wang, Tsing-Hua Her, Lee Casperson, “Power characteristics of homogeneously broadened index-antiguided waveguide lasers,” submitted to Optics Letters (2012).
Metafibers and metafabrics
Category: metamaterials, metasurface, reflective array antenna, dielectric resonator array, fibers.
Application: Large-scale reflectarray, conformal metasurface, light-weight & wearable metasurface
Phase-sensitive light-matter interaction: coherent control of nonlinear absorption and ablation using bichromatic femtosecond laser
Category: femtosecond & nonlinear optics, arbitrary waveform generation, attosecond pulse, ultrafast phenomena, laser matter interaction, laser material processing, pulse shaping.
Application: laser nanofabrication with higher resolution, more efficient and precise laser ablation tools for industry &LASIK, laser direct energy sources.
Femtosecond laser is known to produce nanoscale features in material removal and modification. Key to this fascinating property is it deposits energy into electrons faster than phonons can take it away so energy is effectively localized to remove bonding among atoms.
In this research we explore methods to shape the electric field of laser beams to create transient field pattern that is distinct from conventional sinusoidal oscillation. This could improve energy coupling from laser to electrons. Applications include improving speed and power budget for laser material processing in drilling/cutting/laser weapon, creating features less than 100 nm for nanofabrication, more efficient laser electron accelerator, etc. Students who are interested in this work please contact THRG for more information.
Fiber Fabry-Perot microresonator
Category: optical microresonators, fiber optics, beam shaping
Application: controlled strong coupling with single emitters & single-photon sources, cavity-enhanced optical measurement & sensing (absorption, fluorescence, Raman, Mie scattering, etc.), cavity-enhanced nonlinear optics, tunable filters, precision metrology.