Towards Water-Free Tellurite Glass Fiber for 2–5 μm Nonlinear Applications
X. Feng, J. Shi, M. Segura, N. White, P. Kannan, L. Calvez, X. Zhang, L. Brilland, and W. Loh
Abstract
We report our recent progress on fabricating dehydrated tellurite glass fibers. Low OH content (1 ppm in weight) has been achieved in a new halogen-containing lead tellurite glass fiber. Low OH-induced attenuation of 10 dB/m has been confirmed in the range of 3–4 µm using three measurement methods. This shows the dehydrated halo-tellurite glass fiber is a promising candidate for nonlinear applications in a 2–5 µm region.
Watt-level optical parametric amplifier at 42 MHz tunable from 1.35 to 4.5 μm coherently seeded with solitons
T. Steinle, A. Steinmann, R. Hegenbarth, and H. Giessen
Abstract
We report on an optical parametric amplifier at high repetition rate of 41.7 MHz seeded by an optical soliton from a tapered fiber. Gap-free signal tuning from 1.35 μm to 1.95 μm with corresponding idler wavelengths from 2.2 μm to 4.5 μm is demonstrated. The system provides up to 1.8 W average power at 1.4 μm, more than 1.1 W up to 1.7 μm, and more than 400 mW up to 4.0 μm with a signal pulse duration of 200 to 300 fs. It is directly pumped by a solid-state oscillator providing up to 7.4 W at 1.04 μm wavelength with 425 fs pulse duration. Soliton-seeding is shown to lead to excellent pulse-to-pulse stability, but it introduces a timing-jitter on the millisecond timescale. Using a two-stage concept the timing-jitter is efficiently suppressed due to the passive synchronization of both conversion stages.
Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy
Y. Jin, S. M. Cristescu, F. J. M. Harren, and J. Mandon
Abstract
We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250 cm-1 within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000 cm-1, indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.
High repetition rate femtosecond double pass optical parametric generator with more than 2 W tunable output in the NIR
H. Linnenbank and S. Linden
Abstract
We demonstrate a highly efficient double pass optical parametric generator based on periodically poled MgO-doped congruent LiNbO3. More than two watts of tunable near-IR radiation (1370-1650 nm) are generated by directly pumping the system with 550 fs pulses from a 42 MHz repetition rate passively mode-locked Yb:KGW oscillator. Pulse durations below 200 fs were achieved without further compression techniques. The system is extremely efficient, compact, cost effective, easy to align and easy to operate, which makes it an interesting alternative to more complex optical parametric oscillators or optical parametric amplifiers.
Sellmeier and thermo-optic dispersion formulas for the extraordinary ray of 5 mol. % MgO-doped congruent LiNbO3 in the visible, infrared, and terahertz regions
N. Umemura, D. Matsuda, T. Mizuno, and K. Kato
Abstract
This paper reports the high-accuracy Sellmeier and thermo-optic dispersion formulas for the extraordinary ray of 5 mol. % MgO-doped congruent LiNbO3 that provide excellent reproduction of the temperature-dependent quasi-phase-matching conditions in the 0.39-4.95μm and 150-270 μm ranges. We believe that these equations would be highly useful for designing the frequency conversion system based on periodically poled MgO-doped LiNbO3.
Yb-fiber amplifier pumped idler-resonant PPLN optical parametric oscillator producing 90 femtosecond pulses with high beam quality
L. Xu, J. S. Feehan, L. Shen, A. C. Peacock, D. P. Shepherd, D. J. Richardson, and J. H. V. Price
Abstract
An idler-resonant femtosecond optical parametric oscillator (OPO) with near-diffraction-limited beam quality (M2 1.05) at 2.4 m is demonstrated. The OPO is synchronously pumped by a femtosecond Yb-fiber amplifier system providing 130 fs pulses with an average power of 4.5 W at 1,050 nm and delivers 90 fs pulses with maximum average powers of 600 mW for the idler and 670 mW for the signal. Tunability is demonstrated across idler (signal) wavelengths from 2.2 to 2.6 m (1.76–2.0 m), limited only by the OPO mirrors. As a demonstration of the utility of the source, the idler pulses are used to generate a supercontinuum from 1,600 to 3,200 nm in a silicon-core fiber.
Combining cw-seeding with highly nonlinear fibers in a broadly tunable femtosecond optical parametric amplifier at 42 MHz.
T. Steinle, S. Kedenburg, A. Steinmann, and H. Giessen
Abstract
We report on a precisely tunable and highly stable femtosecond oscillator-pumped optical parametric amplifier at a 41.7 MHz repetition rate for spectroscopic applications. A novel concept based on cw-seeding of a first amplification stage with subsequent spectral broadening and shaping, followed by two further amplification stages, allows for precise sub-nanometer and gap-free tuning from 1.35 to 1.75 μm and 2.55 to 4.5 μm. Excellent spectral stability is demonstrated with deviations of less than 0.008% rms central wavelength and 1.6% rms bandwidth over 1 h. Spectral shaping of the seed pulse allows precise adjustment of both the bandwidth and the pulse duration over a broad range at a given central wavelength. Transform-limited pulses nearly as short as 107 fs are achieved. More than half a Watt of average power in the near- and more than 200 mW in the mid-infrared with power fluctuations less than 0.6% rms over 1 h provide an excellent basis for spectroscopic experiments. The pulse-to-pulse power fluctuations are as small as 1.8%. Further, we demonstrate for the first time, to the best of our knowledge, that by using hollow-core capillaries with highly nonlinear liquids as a host medium for self-phase modulation, the signal tuning range can be extended and covers the region from 1.4 μm up to the point of degeneracy at 2.07 μm. Hence, the idler covers 2.07 to 4.0 μm.
Y. Jin, S. M. Cristescu, F. J. M. Harren, J. Mandon
Abstract
We demonstrate mid-infrared dual-comb spectroscopy with an optical parametric oscillator (OPO) toward real-time field measurement. A singly resonant OPO based on a MgO-doped periodically poled lithium niobate (PPLN) crystal is demonstrated. Chirped mirrors are used to compensate the dispersion caused by the optical cavity and the crystal. A low threshold of 17 mW has been achieved. The OPO source generates a tunable idler frequency comb between 2.7 and 4.7 μm. Dual-comb spectroscopy is achieved by coupling two identical Yb-fiber mode-locked lasers to this OPO with slightly different repetition frequencies. A measured absorption spectrum of methane is presented with a spectral bandwidth of 300cm−1, giving an instrumental resolution of 0.4cm−1. In addition, a second OPO containing two MgO-doped PPLN crystals in a singly resonant ring cavity is demonstrated. As such, this OPO generates two idler combs (average power up to 220 mW), covering a wavelength range between 2.7 and 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyned signal between the two idler combs, broadband spectra of molecular gases can be observed over a spectral bandwidth of more than 350cm−1. This special cavity design allows the spectral resolution to be improved to 0.2cm−1 without locking the OPO cavity, indicating that this OPO represents an ideal high-power broadband mid-infrared source for real-time gas sensing.
Compact, low-noise, all-solid-state laser system for stimulated Raman scattering microscopy
T. Steinle, V. Kumar, A. Steinmann, M. Marangoni, G. Cerullo, and H. Giessen
Abstract
We present a highly stable and compact laser source for stimulated Raman scattering (SRS) microscopy. cw-seeding of an optical parametric amplifier pumped by a bulk femtosecond Yb-oscillator and self-phase modulation in a tapered fiber allow for broad tunability without any optical or electronic synchronization. The source features noise levels of the Stokes beam close to the shot-noise limit at MHz modulation frequencies. We demonstrate the superior performance of our system by SRS imaging of micrometer-sized polymer beads.
High-energy, near- and mid-IR picosecond pulses generated by a fiber-MOPA-pumped optical parametric generator and amplifier
L. Xu, H.-Y. Chan, S. Alam, D. J. Richardson, and D. P. Shepherd
Abstract
We report a high-energy picosecond optical parametric generator/amplifier (OPG/A) based on a MgO:PPLN crystal pumped by a fiber master-oscillator-power-amplifier (MOPA) employing direct amplification. An OPG tuning range of 1450-3615 nm is demonstrated with pulse energies as high as 2.6 μJ (signal) and 1.2 μJ (idler). When seeded with a ~100 MHz linewidth diode laser, damage-limited pulse energies of 3.1 μJ (signal) and 1.3 μJ (idler) have been achieved and the signal pulse time-bandwidth product is improved to ~2 times transform-limited. When seeded with a 0.3 nm-bandwidth filtered amplified spontaneous emission source, crystal damage is avoided and maximum pulse energies of 3.8 μJ (signal) and 1.7 μJ (idler) are obtained at an overall conversion efficiency of 45%.
