Kirk A. Ingold

Sub-50 fs pulses around 2070 nm from a synchronously-pumped, degenerate OPO

We report generation of 48 fs pulses at a center wavelength of 2070 nm using a degenerate optical parametric oscillator (OPO) synchronously-pumped with a commercially available 36-MHz, femtosecond, mode-locked, Yb-doped fiber laser. The spectral bandwidth of the output is ~137 nm, corresponding to a theoretical, transform-limited pulse width of 33 fs. The threshold of the OPO is less than 10 mW of average pump power. By tuning the cavity length, the output spectrum covers a spectral width of more than 400 nm, limited only by the bandwidth of the cavity mirrors.

Fractional-length sync-pumped degenerate optical parametric oscillator for 500-MHz 3-μm mid-infrared frequency comb generation

We demonstrate a mid-IR frequency comb centered at 3120 nm with 650-nm (20-THz) bandwidth at a comb-teeth spacing of 500 MHz. The generated comb is based on a compact ring-type synchronously pumped optical parametric oscillator (SPOPO) operating at degeneracy and pumped by a mode-locked Er-doped 1560 nm fiber laser at a repetition rate of 100 MHz. We achieve high-repetition rate by using a fractional-length cavity with a roundtrip length of 60 cm, which is one-fifth of the length dictated by conventional synchronous pumping.

Cascaded half-harmonic generation of femtosecond frequency combs in the mid-infrared

There is a growing demand for frequency combs in the mid-infrared (mid-IR), also known as the “molecular fingerprint” region of the spectrum. Down-conversion of near-IR frequency combs by half-harmonic generation is a simple way to extend the wavelength coverage of stable frequency combs to this region, and has benefits such as high conversion efficiency and intrinsic phase and frequency locking to the near-IR pump. Here, we report a two-octave down-conversion of a frequency comb around 1 μm through cascaded half-harmonic generation with ∼64% efficiency in the first stage and ∼18% in the second stage. The high conversion efficiency and stable broadband operation indicate the effectiveness and potential of cascaded half-harmonic generation for the realization of intrinsically locked long-wavelength sources, which can be beneficial for numerous applications.

Fiber-feedback optical parametric oscillator for half-harmonic generation of sub-100-fs frequency combs around 2 μm

We demonstrate a femtosecond fiber-feedback optical parametric oscillator (OPO) at degeneracy. The OPO cavity comprises an 80-cm-long fiber composed of a combination of normal and anomalous dispersion sections that provide a net intracavity group delay dispersion close to zero. By using a mode-locked, Yb-doped fiber laser as the pump, we achieved half-harmonic generation of 250-MHz, 1.2-nJ nearly transform-limited 97-fs pulses centered at 2090 nm with a total conversion efficiency of 36%.

2.09-µm degenerate femtosecond OPO with over 60% conversion efficiency and 0.6-W output

We report a broad frequency comb centered at 2.09 μm produced by a degenerate OPO. We achieve 0.6 W of 94-fs transform limited pulses at 250 MHz and a conversion efficiency of 64%.

Efficient cascaded half-harmonic generation of femtosecond frequency combs centered at 2.09 μm and 4.18 μm from a mode-locked Yb:Fiber laser

We report efficient generation of sub-50-fs pulses at 2.09 μm and 110-fs pulses at 4.18 μm from two cascaded half-harmonic PPLN-based OPOs, which are intrinsically phase-locked to the 250-MHz mode-locked fiber laser pump.

Sub-100fs fiber feedback synchronously pumped degenerate optical parametric oscillator

We report on a synchronously pumped degenerate OPO operated at 250 MHz that generates 280 mW of transform-limited sub-100 fs pulses at 2.09 μm using a compact dispersion-compensated fiber feedback cavity.

Quarter-harmonic generation of femtosecond pulses at 4.18 μm from a mode-locked Yb:Fiber laser

We report generation of 104 mW of 110-fs pulses at 4.18 μm using two cascaded sub-harmonic PPLN-based optical parametric oscillators pumped by a 950-mW Yb:fiber mode-locked laser at 250 MHz with expected intrinsic phase-locking.

500-MHz mid-IR frequency comb source based on a compact subharmonic OPO

We demonstrate a degenerate mid-infrared frequency comb OPO with a fractional cavity length pumped by an ultrafast 100-MHz Er-nber laser. This produces a 600-nm wide output near 3μπι with a repetition rate of 500 MHz.