DFB Single-Mode QCL Lasers - Precision Mid-IR for Gas Spectroscopy

Ultra-Narrow Linewidth Quantum Cascade Lasers for Sensitive Detection

When applications demand the highest spectral purity and wavelength stability in the mid-infrared region, Distributed Feedback (DFB) Quantum Cascade Lasers from Alpes Lasers deliver unmatched performance. These single-mode laser modules enable ppb-level gas detection, precision interferometry, and advanced spectroscopic measurements.

Understanding DFB QCL Technology

Distributed Feedback lasers incorporate a periodic structure directly into the laser cavity, creating wavelength-selective feedback that forces the laser to operate in a single longitudinal mode. This architecture produces an ultra-narrow emission line essential for high-resolution spectroscopy.

Exceptional Specifications

Alpes Lasers' DFB QCL modules deliver:

  • Output Power: 1-120 mW in continuous wave (CW) operation
  • Wavelength Coverage: 3-12 microns (both QCL and ICL technologies)
  • Spectral Linewidth: <30 MHz for ultimate resolution
  • Wavelength Stability: Tunable output with precise temperature control
  • Mode Purity: True single-mode operation across entire tuning range

Why Single-Mode Matters

Gas spectroscopy relies on detecting narrow absorption features in molecular spectra. The laser linewidth must be significantly narrower than the gas absorption line to achieve maximum sensitivity. Multi-mode lasers spread their energy across many wavelengths, reducing the power at any single frequency and degrading detection limits.

DFB lasers concentrate all optical power into a single, narrow spectral line that can be precisely tuned to match the absorption peak of the target molecule. This approach enables:

  • Parts-per-billion (ppb) detection sensitivity
  • Species-selective measurements in complex gas mixtures
  • Quantitative analysis with linear response over wide concentration ranges
  • Real-time monitoring with millisecond time resolution

Gas Spectroscopy Applications

DFB QCLs excel at detecting gases with strong absorption features in the mid-infrared molecular fingerprint region:

Environmental Monitoring:

  • Greenhouse gas measurement (CO₂, CH₄, N₂O)
  • Air quality monitoring (NO₂, SO₂, O₃)
  • Water and ground pollution detection
  • Microplastic contamination assessment

Industrial Process Control:

  • Semiconductor manufacturing (SiF₄, NH₃)
  • Oil & gas leak detection
  • Process monitoring and optimization
  • Hazardous substance detection

Medical Diagnostics:

  • Breath analysis for volatile organic compounds (VOCs)
  • Blood and fluid analysis
  • Early disease detection
  • Non-invasive patient monitoring

Food Safety:

  • Contaminant detection
  • Spoilage indicators
  • Quality control measurements
  • Authenticity verification

DFB QCL with Extended Tuning (QC-XT)

For applications requiring broader wavelength coverage, Alpes Lasers offers QC-XT technology that combines DFB single-mode operation with extended tuning capability:

  • Tuning Range: Approximately 40 cm⁻¹ continuous tuning
  • Output Power: Around 5 mW CW operation
  • Wavelength Options: Five spectral ranges between 1000-2200 cm⁻¹
  • Multi-Compound Analysis: Detect multiple gas species with a single laser

The QC-XT leverages the Vernier effect to achieve wide tuning while maintaining single-mode operation, offering a cost-effective alternative to multiple single-frequency DFB lasers.

Packaging Options for Every Application

Alpes Lasers provides DFB QCLs in multiple package configurations:

HHL Package: Ruggedized housing with integrated thermoelectric cooler, ideal for field instruments and demanding environments.

LLH Package: Versatile design with excellent thermal management for laboratory applications.

TO-3 Package: Compact form factor for space-constrained designs.

Submount Package: Maximum flexibility for OEM integrators building custom systems.

Fiber-Coupled Options: Single-mode or multimode fiber delivery with high coupling efficiency (3-10 micron wavelength range).

Off-The-Shelf DFB Lasers

For commonly used wavelengths, Alpes Lasers offers standardized DFB lasers in HHL housing through their e-commerce platform with delivery in less than 10 days:

Frequency (cm⁻¹) Target Gas Species
1030 SiF₄, CH₃CN, NH₃
1046.3 NH₄, C₆₀
1103.5 CH₃CHO
1900 NO
2209 CO, N₂O
2311 CO₂

This rapid delivery option accelerates system development and enables quick deployment of gas sensing instruments.

QCL Starter Kits

For researchers new to QCL technology, Alpes Lasers offers complete QCL Starter Kits that include:

  • DFB laser in HHL package
  • Current driver (S-2m standard or S-4 low-noise versions)
  • All necessary cables and accessories
  • Documentation and application notes

These kits provide everything needed to begin exploring mid-IR spectroscopy applications without the complexity of sourcing individual components.

Technical Advantages Over Alternatives

Compared to alternative mid-IR sources, DFB QCLs offer compelling advantages:

vs. FTIR Spectrometers:

  • 100-1000× better sensitivity
  • Real-time, in-situ measurements
  • Compact, portable designs
  • Lower cost for single-gas applications

vs. Tunable Diode Lasers:

  • Higher output power
  • Broader wavelength coverage
  • Room temperature operation
  • Superior beam quality

vs. Multi-Mode QCLs:

  • Ultra-narrow linewidth for selectivity
  • Maximum detection sensitivity
  • Quantitative accuracy
  • Interferometric capability

Integration and Customization

Alpes Lasers works closely with OEM partners to customize DFB QCL solutions for specific applications. Whether you need custom wavelengths, specialized packaging, or modified output characteristics, the company's in-house wafer fabrication and design capabilities enable true customization.

The Swiss manufacturing approach ensures every laser meets stringent quality standards with comprehensive testing before delivery.

Advancing Science and Safety

DFB Quantum Cascade Lasers from Alpes Lasers are enabling breakthroughs across multiple fields—from climate science to medical diagnostics. Their combination of sensitivity, selectivity, and reliability makes them the gold standard for mid-infrared gas spectroscopy.

Contact us to discuss your spectroscopy requirements and discover how DFB QCL technology can enhance your measurement capabilities.

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