Peer reviewed research papers

Abstract - We present a configurable guided-wave planar glass-chip laser that produces low-noise and high-quality continuous-wave laser emission tunable from 2.82 to 2.95 μm. The laser has a low threshold and intrinsic power and mode stability attributable to the high overlap of gain volume and pump mode defined by an ultrafast laser inscribed waveguide. The laser emission is single transverse-mode with a Gaussian spatial profile and M2 x,y ∼ 1.05, 1.10. The power drift is ∼0.08% rms over ∼2 h. When configured in a spectrally free-running cavity, the guided-wave laser emits up to 170 mW. The benefit of low-noise and stable wavelength emission of this hydroxide resonant laser is demonstrated by acquiring high signal-to-noise images and spectroscopy of a corroded copper surface film with corrosion products containing water and hydroxide ions with a scattering-scanning near-field optical microscope.

Abstract - A guided-wave chip laser operating in a single longitudinal mode at 2860 nm is presented. The cavity was set in the Littman-Metcalf configuration to achieve single-frequency operation with a side-mode suppression ratio above 33 dB. The chip laser’s linewidth was found to be limited by mechanical fluctuations, but its Lorentzian contribution was estimated to be lower than 1 Hz using a heterodyne technique. This demonstration incorporates a high coherence source with the simplicity provided by the compactness of chip lasers. 

Abstract - We report efficient 1.55-µm laser operation in a waveguide chip laser femtosecond-laser inscribed in bulk fluorozirconate glass. The ternary doped glass is composed of erbium as the active laser ion, ytterbium sensitizer, and cerium to enhance the branching ratio from the pump to the erbium upper laser state. We have achieved slope efficiencies up to 25%, with a low 100-mW threshold. To meet diverse application requirements, we also report the wide tunability of 1507–1593 nm, and large single-transverse-mode Gaussian beam-output from the 55 µm diameter waveguides.

Abstract -  We report a large mode-area holmium-doped ZBLAN waveguide laser operating at 2.9 μm, which was pumped by a 1150 nm diode laser. The laser is based on ultrafast laser inscribed depressed cladding waveguides fabricated in uniformly rare-earth-doped bulk glass. It has a threshold of 28 mW and produced up to 27 mW of output power at an internal slope efficiency of approximately 20%. 

Abstract - We report mode-locked ~1550 nm output of transform-limited ~180 fs pulses from a large mode-area (diameter ~ 50 μm) guided-wave erbium fluorozirconate glass laser. The passively mode-locked oscillator generates pulses with 25 nm bandwidth at 156 MHz repetition rate and peak-power of 260 W. Scalability to higher repetition rate is demonstrated by transform-limited 410 fs pulse output at 1.3 GHz. To understand the origins of the broad spectral output, the laser cavity is simulated by using a numerical solution to the GinzburgLandau equation. This paper reports the widest bandwidth and shortest pulses achieved from an ultra-fast laser inscribed waveguide laser. 

Abstract - We report widely tunable (»260 nm) Tm3+ and Ho3+ doped fluorozirconate (ZBLAN) glass waveguide extended cavity lasers with close to diffraction limited beam quality (M2 »1.3). The waveguides are based on ultrafast laser inscribed depressed claddings. A Ti:sapphire laser pumped Tm3+-doped chip laser continuously tunes from 1725 nm to 1975 nm, and a Tm3+-sensitized Tm3+:Ho3+ chip laser displays tuning across both ions evidenced by a red enhanced tuning range of 1810 to 2053 nm. We also demonstrate a compact 790 nm diode laser pumped Tm3+-doped chip laser which tunes from 1750 nm to 1998 nm at a 14% incident slope efficiency, and a beam quality of M2 »1.2 for a large mode-area waveguide with 70 µm core diameter.

Abstract - We report performance characteristics of a thulium doped ZBLAN waveguide laser that supports the largest fundamental modes reported in a rare-earth doped planar waveguide laser (to the best of our knowledge). The high mode quality of waveguides up to 45 um diameter (~1075 μm2 mode-field area) is validated by a measured beam quality of M2 ~1.1 ± 0.1. Benefits of these large mode-areas are demonstrated by achieving 1.9 kW peak-power output Q-switched pulses. The 1.89 μm freerunning cw laser produces 205 mW and achieves a 67% internal slope efficiency corresponding to a quantum efficiency of 161%. The 9 mm long planar chip developed for concept demonstration is rapidly fabricated by single-step optical processing, contains 15 depressed-cladding waveguides, and can operate in semi-monolithic or external cavity laser configurations.