High-power supercontinuum generation in the mid-infrared pumped by a soliton self-frequency shifted source.

We report the demonstration of a fiber-based supercontinuum source delivering up to 825 mW of average output power between 2.5 and 5.0 µm generated in all-normal dispersion regime. The pumping source consists of an amplified ultrafast Er3+:ZrF4 fiber laser providing high peak power femtosecond pulses at 3.6 µm with an average output power exceeding the watt-level. These pulses are spectrally broadened through self-phase modulation using commercial chalcogenide-based step-index fibers. Al2O3 anti-reflection coatings were sputtered on chalcogenide fiber tips to increase the launching efficiency from 54% to 82%, making this record output power possible, and thus confirming that such coatings can support watt-level pumping with intense femtosecond pulses. To the best of our knowledge, this result represents the highest average output power ever achieved from a As2Se3-based mid-IR supercontinuum source with the potential of a high degree of coherence.

Infrared supercontinuum generated in concatenated InF3 and As2Se3 fibers.

We report on infrared supercontinuum (SC) generation through subsequent nonlinear propagation in concatenated step-index fluoride and As2Se3 fiber. These fibers were pumped by an all-fiber laser source based on an erbium amplifier followed by a thulium power amplifier. ZBLAN and InF3 fibers were compared for the concatenated scheme. The broadest SC produced was achieved by optimizing the length of the InF3 fiber. This arrangement allowed the generation of 200 mW infrared SC with high spectral flatness and spanning from 1.4 µm to 6.4 µm.

Generation of near-diffraction-limited, high-power supercontinuum from 1.57 µm to 12 µm with cascaded fluoride and chalcogenide fibers.

We generate a supercontinuum (SC) spectrum ranging from 1.57 µm to 12 µm (20 dB bandwidth) with a soft glass fiber cascade consisting of ZrF4-BaF2-LaF3-AlF3-NaF fiber, As2S3 fiber, and As2Se3 fiber pumped by a nanosecond thulium master oscillator power amplifier system. The highest on-time average power generated is 417 mW at 33% duty cycle. We observe a near-diffraction-limit beam quality across the wavelength range from 3 µm to 12 µm, even though the As2Se3 fiber is multimode below 12 µm. Our study also shows that parameters of the As2Se3 fiber, such as numerical aperture, core size, and core/cladding composition, have significant effects on the long wavelength edge of the generated SC spectrum. Our results suggest that the high numerical aperture of 0.76 and low-loss As2Se3/GeAs2Se5 core/cladding material all contribute to broad SC generation in the long-wave infrared spectral region. Also, among our results, 10 µm core diameter selenide fiber yields the best spectral expansion, while the 12 µm core diameter selenide fiber yields the highest output power.

Compact 3-8 µm supercontinuum generation in a low-loss As2Se3 step-index fiber.

A mid-infrared supercontinuum source spanning from 3 to 8 µm is demonstrated using a low-loss As2Se3 commercial step-index fiber. A maximum average output power of 1.5 mW is obtained at a low repetition rate of 2 kHz. Thanks to the low NA step-index fiber, the output is single mode for wavelengths above ∼5 µm. The pump source consists of an erbium-doped ZrF4-based in-amplifier supercontinuum source spanning from 3 to 4.2 µm. The effects of both the pump power and As2Se3 fiber length on the output characteristics are studied. To the best of our knowledge, this is the first compact supercontinuum source ever reported to reach 8 µm in a standard step-index fiber.

Broadband amplification of high power 40 Gb/s channels using multimode Er-Yb doped fiber.

Broadband amplification of several high power communication channels is demonstrated using a multimode Erbium-Ytterbium doped fiber (EYDF) amplifier. The multimode feature of this amplifier aims at simultaneously enabling wide gain bandwidth and high output power. The amplifier provides a gain bandwidth spanning over the 1535.0 nm-1565.8 nm band. The amplifier also provides a high output power of >30.2 dBm, with ± 2.4 dB natural gain flatness over the bandwidth of interest. The performance of the amplifier is assessed in a 40 Gb/s WDM system, featuring no trace of modal dispersion in the eye diagram and a low power penalty (< 0.4 dB) on the bit error ratio (BER).