40 W Main Oscillator + OPA + SHG + DFG - Five Units, One Bench, 315 nm – 16 μm

In ultrafast spectroscopy, whether an experiment runs comes down to whether the driver wavelength matches the target absorption band. The π–π* electronic transitions of aromatic molecules sit in the near-UV to violet-visible window (~250 – 400 nm, extending to ~450 nm for larger conjugated systems). Chromophore absorption in biology and the MLCT (metal-to-ligand charge-transfer) bands of transition-metal complexes fall in the visible (400 – 650 nm). Perovskite band edges and TMD excitonic transitions lie in the visible-to-NIR (500 – 1000 nm). Charge-transfer (CT) states in organic donors–acceptors (~800 – 1500 nm) and interband absorption in colloidal quantum dots (~600 nm – 2.5 μm) live in the NIR-to-SWIR. And molecular vibrational fingerprints live in the mid-IR (~2 – 20 μm): C-H / O-H / N-H / C=O stretches, Amide I / II bands, DNA phosphate-backbone stretches, and M-O phonon modes of inorganic oxides.

Y-LASER’s five-unit configuration — HELIOS-40W-HP + AURORA-HE + standalone SHG + standalone DFG1 + standalone DFG2 — is engineered against exactly this cross-cutting requirement. All five units are Y-LASER products, delivered together, calibrated together, and installed on a single bench as one tuned optical chain that spans 315 nm to 16 μm continuously.

1 · Highlights at a Glance

2 · OPA + SHG + DFG in 30 seconds

In plain terms:

▪ ▶ OPA (Optical Parametric Amplification) — inside a nonlinear crystal, one 1030 nm pump photon "splits" into a Signal photon and an Idler photon under energy conservation ω_p = ω_s + ω_i. Rotating the crystal moves the Signal continuously from 630 to 1030 nm; the Idler tracks by energy conservation from 1030 to 2600 nm on the other side.

▪ ▶ SHG (Second-Harmonic Generation) — two fundamental photons at ω "combine" into one 2ω photon, halving the wavelength. Doubling the OPA Signal covers 315 – 515 nm deep-UV (SHS); doubling the Idler covers 515 – 630 nm visible (SHI).

▪ ▶ DFG (Difference-Frequency Generation) — two higher-energy photons (e.g., Signal & Idler) "subtract" to yield a longer-wavelength mid-IR photon at ω₁ − ω₂. DFG1 delivers 2.2 – 4.1 μm (group-frequency region, ~2400 – 4500 cm⁻¹); DFG2 delivers 4 – 16 μm (molecular fingerprint region, ~625 – 2500 cm⁻¹).

Combined, OPA + SHG + DFG turn one 1030 nm Yb main oscillator into a continuous 315 nm – 16 μm tunable femtosecond source spanning six orders of magnitude in wavelength.

3 · A Five-Unit Y-LASER Configuration

The full system consists of five separate units — every one designed, built, and calibrated by Y-LASER — installed as a single tuned optical chain on one bench:

▪ HELIOS-40W-HP high-power main oscillator — 1030 nm Yb-CPA · 44.2 W average power · 100 kHz / 442 μJ / 199.4 fs · 24 h power stability 0.04 % RMS · M² < 1.11.

▪ AURORA-HE OPA — optical parametric amplifier; Signal 630 – 1030 nm and Idler 1030 – 2600 nm continuously tunable; peak conversion 10.4 % @ 700 nm.

▪ Standalone SHG doubling stage — separate chassis, fed by OPA Signal / Idler; SHS 315 – 515 nm deep-UV + SHI 515 – 630 nm visible.

▪ Standalone DFG1 stage — separate chassis, fed by OPA Signal + Idler; 2.2 – 4.1 μm mid-IR (C-H / O-H / N-H stretch region).

▪ Standalone DFG2 stage — separate chassis; 4 – 16 μm far mid-IR, covering the molecular fingerprint region (Amide I / II bands, DNA phosphate backbone, M-O phonon modes of inorganic oxides).

Because all five units come from a single design house, the polarization, dispersion, phase-matching handoffs and beam-height interfaces between them are calibrated together at the factory and finalized during on-site commissioning — removing the interface-loss and drift issues typical of multi-vendor mid-IR chains.

4 · Why It Matters — the Data Speaks

■ Advantage 1 · HELIOS-40W-HP main oscillator: 44 W · 24 h 0.04 % RMS

The main oscillator caps how much conversion the whole chain can extract. HELIOS-40W-HP delivers 44.2 W average power at the 100 kHz working point (442 μJ single-pulse energy, 199.4 fs); 24 h power stability sits at 0.04 % RMS and M² is below 1.11 — a top-tier envelope for driving downstream OPA, SHG and DFG stages.

HELIOS-40W-HP | Output Spectrum @ 100 kHz · λc = 1037.9 nm	HELIOS-40W-HP | Autocorrelation @ 100 kHz · Pulse Duration = 199.4 fs (FWHM)
HELIOS-40W-HP | 24 h Power Stability · 44.2 W · 0.04 % RMS	HELIOS-40W-HP | 24 h Pointing Stability · 1.91 μrad · RMS = 0.955 μm

■ Advantage 2 · OPA Signal tuning spectra (630 – 1030 nm)

More than 24 tuning wavelengths across 630 – 1030 nm — each with a clean, complete peak, uniform amplitude, and no distortion at adjacent points. Peak conversion 10.4 % @ 700 nm, peak power 3220 mW — enough visible-to-NIR photon flux for downstream TA pump-probe.

■ Advantage 3 · OPA Idler tuning spectra (1030 – 2600 nm)

Idler covers the NIR and SWIR — peak 1921 mW @ 1100 nm (6.4 %). Beyond direct TA probing, the Idler is the crucial seed for the downstream DFG stages, where mid-IR photons are generated by mixing Signal and Idler.

AURORA-HE OPA | Signal Tuning Spectra (630 – 1030 nm)	AURORA-HE OPA | Idler Tuning Spectra (1030 – 2600 nm)

■ Advantage 4 · Standalone SHG · deep-UV extension (SHS · 315 – 515 nm)

Doubling the OPA Signal covers 315 – 515 nm near-UV to violet-visible — the window of the π–π* electronic transitions of aromatic molecules, the MLCT bands of transition-metal complexes, and the UV absorption windows of catalytic intermediates. Peak SHS conversion 3.6 % @ 400 nm, peak power 1113 mW.

■ Advantage 5 · Standalone SHG · visible extension (SHI · 515 – 630 nm)

Doubling the OPA Idler covers 515 – 630 nm in the visible — filling the gap between OPA Signal at 630 nm and SHS at 515 nm, so the tuning is truly continuous across every spectral region. Peak SHI conversion 2.63 % @ 550 nm, peak power 815 mW — suitable for chromophore, photosensitive-protein and fluorescent-probe excited-state dynamics.

Standalone SHG | SHS Tuning Spectra (315 – 515 nm)	Standalone SHG | SHI Tuning Spectra (515 – 630 nm)

■ Advantage 6 · Standalone DFG1 · mid-IR (2.2 – 4.1 μm) ★ group-frequency region

DFG1 covers the ~3000 – 4500 cm⁻¹ group-frequency region: C-H stretches (~3.3 μm / 3000 cm⁻¹), O-H stretches (~2.7 – 3.0 μm), and N-H stretches (~2.9 – 3.1 μm). Peak conversion 5.3 % @ 2.9 μm, peak power 1640 mW — plenty of mid-IR photon flux for catalytic intermediates, photochemistry and TA-MIR.

■ Advantage 7 · Standalone DFG2 · far mid-IR (4 – 16 μm) ★ molecular fingerprint region

DFG2 covers the molecular fingerprint region (~500 – 1500 cm⁻¹ / 6.7 – 20 μm): protein Amide I band (~1650 cm⁻¹ / 6.06 μm) and Amide II band (~1550 cm⁻¹ / 6.45 μm), DNA phosphate-backbone asymmetric stretch (~1240 cm⁻¹ / 8.1 μm) and symmetric stretch (~1080 cm⁻¹ / 9.3 μm), plus M-O phonon modes of inorganic oxides (~400 – 1000 cm⁻¹). This band has historically been the territory of QCLs and free-electron lasers; delivering it from a table-top femtosecond OPA + DFG chain is the key differentiator of this configuration versus a conventional 315 – 2600 nm OPA + SHG. Peak conversion 0.4 % @ 7 μm, peak power 125 mW.

Standalone DFG1 | Mid-IR Tuning Spectra (2.2 – 4.1 μm)	Standalone DFG2 | Far-Mid-IR Tuning Spectra (4 – 16 μm)

■ Advantage 8 · Full tuning curve — 315 nm – 16 μm in one view

Signal + Idler + SHS + SHI + DFG1 + DFG2 on the same axis — the horizontal axis runs from 315 nm to 16 μm across all six spectral regions. The six arms stitch together seamlessly, giving a direct visual of what "five units, one bench, six spectral regions" actually delivers.

AURORA-HE + SHG + DFG | Full Spectral Tuning Curve (315 nm – 16 μm)

5 · Experiments Unlocked by One Bench

▪ Femtosecond mid-IR transient absorption (TA-MIR) — DFG1 + DFG2 cover 2 – 16 μm molecular vibrational bands for catalytic intermediates, photochemistry, and fingerprint-region probing.

▪ Transient vibrational spectroscopy (TVS) — Amide I / II bands of proteins, DNA phosphate backbone modes, and other biomolecular conformational dynamics on the femtosecond time scale.

▪ Vibrational sum-frequency generation (VSFG) — interfacial molecular structure and dynamics.

▪ TMD exciton–phonon coupling — OPA Signal / Idler probe the excitonic transitions; DFG probes low-frequency phonon modes.

▪ UV-Vis TA pump-probe — SHS + SHI cover aromatic π–π* transitions, MLCT bands, and biological chromophore absorption.

6 · Closing Notes

44 W main oscillator · 10.4 % Signal peak · 6.4 % Idler peak · 3.6 % SHS peak · 5.3 % DFG1 peak · 315 nm – 16 μm continuous tuning · main-oscillator 24 h stability 0.04 % RMS — the numbers delivered by Y-LASER HELIOS-40W-HP + AURORA-HE + standalone SHG + standalone DFG1 + standalone DFG2 map one-to-one onto the six physical requirements that ultrafast mid-IR spectroscopy experiments actually depend on: main-oscillator power, Signal efficiency, Idler efficiency, UV extension, mid-IR coverage, and long-term stability.

The standalone DFG2 unit — pushing the tuning out to 16 μm across the molecular fingerprint region — is the key differentiator that sets this configuration apart from a conventional OPA + SHG combination. Because all five units come from the same vendor, the polarization, dispersion, phase-matching handoffs and beam-height interfaces between them are calibrated together at the factory and finalized during on-site commissioning — physically lowering the baseline noise floor of every downstream TA / TVS signal.