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Enhanced-Stability CW-Mode Hop-Free Mid-IR Laser

Daylight Solutions is proud to introduce the TLS-41000-MHF, a new generation of mode hop-free (MHF) lasers.  A complete redesign based on Finite Element Analysis (FEA) maximizes the lasers robustness with respect to vibrations and acoustic perturbations.  A factor of 5 linewidth reduction (now <10 MHz over a 1 s integration time) over our previous model and maximum stability are combined with new modulation capabilities to provide the ultimate tool for high-resolution spectroscopy and sensor development.

Our highest-performing tunable external cavity laser, the CW-MHF series provides continuous tuning in the mid-IR. The combination of a narrow linewidth and excellent wavelength control allows for highly resolved spectral features in both survey and short, high-resolution scans. Two options for wavelength modulation are standard on the TLS-41000-MHF series:  piezoelectric (PZT) for low bandwidth (DC to 350 Hz) and current modulation for high bandwidth (200 Hz to 1 MHz).  Both systems have been improved, increasing and overlapping their response bandwidths.  


  • Wavelength availability: < 4 to > 11 µm
  • Mode-Hop-Free tuning range: 60 cm-1 typical, ≥30 cm-1 guaranteed
  • CW output power: >70 mW typical
  • Wavelength accuracy: ±0.5 cm-1 (±15 GHz), unidirectional
  • Linewidth as low as 5 MHz(1)
  • Improved PZT modulation bandwidth: 0-350 Hz
  • Improved current modulation bandwidth: 200 Hz – 1 MHz
  • Highly collimated beam
  • Controller includes TEC and laser driver
  • Room temperature operation with only a water chiller

(1) Over 100 ms


  • Center wavelengths covering most of the mid-IR
  • Broad tuning range – see more molecules per laser
  • See CH4, CO2, CO, NO, N2O, NO2, NH3, H2O, & many more molecules
  • High-power means easy experimental design & often no need for LN2-cooled detectors
  • Accuracy is built in. No need for a wavemeter for many experiments
  • New level of resolution
  • Open-loop experimental versatility and overlapping control bandwidths mean maximum control in closed-loop experiments
  • More usable photons
  • Convenient, turn-key product
  • No cryogenic cooling

Product Details

Daylight Solutions is pleased to announce the TLS-41000-MHF – the next generation of broadly tunable, mode hop-free (MHF), mid-IR lasers based on quantum cascade and diode laser technology. Center wavelengths of the series span the mid-IR spectrum from < 4 μm to > 11 μm and provide guaranteed continuous tuning of at least 30 cm-1.

The highly successful Mode Hop-Free laser product line has been completely redesigned for higher stability and increased versatility.  Guided by an exhaustive Finite Element Analysis (FEA) of the vibrational modes of the tuning elements, the cavity is now much more resistant to acoustic perturbations and vibrations.  The new design will allow for narrower open-loop linewidth (≤5 MHz with a 100 ms integration time) and reduced jitter both at a single wavelength and while scanning.  The result will be improved quality high-resolution spectra.  The enhanced mechanical stability allows for a dramatic increase in the bandwidth of the piezoelectric tuning element (PZT) to 350 Hz. 

The new TLS-41000-MHF model line also features a redesigned current modulation circuit optimized for high-resolution spectroscopy.  The circuit has a widened bandwidth (200 Hz to over 1 MHz) with low phase delay.  The overlap of the PZT and current modulation bandwidths allows the implementation of a traditional two-stage locking circuit to minimize the center linewidth drift and jitter.  Higher resolution, smoother tuning, and the ability to tightly lock the source to a reference are the hallmarks of this new line of laser products

Offering excellent linewidth characteristics, these CW lasers tune mode hop-free across their specified tuning range. The survey scanning is complemented by PZT and current modulation to perform modulation spectroscopy or stabilization and locking experiments.
Designed by the world’s leading experts in tunable lasers, these sources are small, robust, and utilize specially designed miniature lenses to optimize system performance. Each system integrates a TEC for temperature control, so only a water chiller is needed—no cryogenic cooling!
These lasers are turnkey systems: each comes with an intuitive, easy-to-use SideKick™ multifunction controller. PC remote control is possible via USB 2.0 and Ethernet 10/100 interfaces. This allows external control of the tunable laser for a variety of applications.
Daylight Solutions’ overall system leverages years of tunable-laser development and manufacturing, and incorporates the company’s latest patented  tuning and packaging technology for the mid-IR.
The availability of robust, easy-to-use mode hop-free tunable lasers in the < 4 to > 11 μm region of the spectrum has taken a step up in stability and flexibility. These lasers enable application research in the field of molecular detection and imaging. Common applications include high-resolution spectroscopy, greenhouse gas sensor development, the detection of biomarkers in the breath, and the detection of chemical and biological agents.

This new TLS-41000-MHF featuring highly stable mode hop-free performance is available in a full range of wavelength spanning the mid-IR from < 4 to > 11 µm.
Daylight Solutions – the Source for All Applications in the Mid-IR

Call today for pricing and availability of specific wavelengths


Product Specifications1
Operation Continuous wave, mode hop-free (CW-MHF) + extended CW tuning2
Center Wavelengths Availability: < 4 to > 11 μm
Optical Parameters
Tuning Range Guaranteed ≥ 30 cm-1 minimum, 60 cm-1 typical
Minimum Avg. Power >1 mW across tuning range
Maximum Avg. Power >70 mW typical
Power Variations <1% over 5 mins., <4% avg. over 1 day
Linewidth <5 MHz over 100 ms
<10 MHz over 1 s
Beam Divergence <5 mrad (1/e2 intensity FWHM)
Beam Waist 30–50 cm typical (from exit port)
Polarization Linear, 100:1, Vertical
Pointing Stability <1 mrad per 100 cm-1 tuning
Spot Size Minimum <2.5 mm (1/e2 intensity FWHM)
Beam Quality TEM00 (nominal)
Electrical Parameters
Scanning Uni- and Bi-directional survey scan, Start, Stop, Step, Pause, Auto/Manual scanning programmable
External Interface USB 2.0, Ethernet 10/100
Piezoelectric Modulation
≥ 0.05% of nominal center wavelength {cm-1} at 100 Hz, 350 Hz bandwidth
Current Modulation ≥ 0.02 cm-1, 200 Hz to 500 KHz, 1 MHz bandwidth
Mechanical Parameters
Full Range Tuning Speed <3 sec for 100 cm-1 scan
Display Accuracy ±0.5 cm-1 uni-directional
Display Repeatability <0.02 cm-1 uni-directional
Cooling Requirements4
Water cooling, no cryogenic cooling
Head Size 6.5"  × 4.4"  × 5.73" / 17.2 cm x 11.1 cm x 14.6 cm (L x W x H)

1 All specifications are defined at the peak of tuning curve only, after 5 minutes warm up, and are subject to change without notice
2 In “extended” range, system will mode hop as it is tuned.
3 This laser is an inherently cw laser.  Pulsed operation is not available.
4 Ambient temperature 20°C, 10% to 90% humidity

Industries & Applications

  • Photoacoustic spectroscopy (PAS)
  • Rovibrational spectroscopy
  • Cavity ring-down spectroscopy
  • Wavelength modulation spectroscopy

  • Explosives Detection
  • Photoacoustic spectroscopy
  • Remote sensing
Life Sciences
  • Breath analysis

  • Atmospheric research
  • Pollution monitoring
  • Toxic industrial chemicals detection
  • Cavity ring-down spectroscopy
  • Greenhouse gas monitoring (GHG)
  • Process control
  • Fence line monitoring
  • Toxic industrial chemicals detection
  • Combustion diagnostics

Literature & Downloads



Technical Papers

2014-07-24 Sensitive detection of CO2 concentration and temperature for hot gases using quantum-cascade laser absorption spectroscopy near 4.2 lm [PDF, 1MB]
2014-07-24 Quantum cascade laser–based hyperspectral imaging of biological tissue [PDF, 2MB]
10 October, 2013, Sensitive trace gas detection with cavity enhanced absorption spectroscopy using a continuous wave external-cavity quantum cascade laser [PDF, 800B]
08 August, 2013, On the application of cw external cavity quantum cascade infrared lasers for plasma diagnostics [PDF, 1MB]
08 August, 2013, Applications of quantum cascade lasers in plasma diagnostics: a review [PDF, 2MB]
08 August, 2013, Plasma Chemical Study of a RF Discharge Containing Aluminum Tri-Isopropoxide Using MIR Absorption Spectroscopy Based on External-Cavity Quantum Cascade Lasers [PDF, 190KB]

Daylight Solutions Logo
June 26, 2012, Frequency characterization of an External-Cavity Quantum Cascade Laser at 4.5 µm using a Frequency Comb [PDF, 1.3MB]


Dual beam photoacoustic infrared spectroscopy of solids using an external cavity quantum cascade laser [PDF, 319KB]
11 May 2012, Nonpolar nitrous oxide dimer: Observation of the combination bands of (14N2O)2 and (15N2O)2 involving the torsion and antigeared bending modes [PDF, 965KB]
9 March 2012, Morphed intermolecular potential of OC:HCCH complex based on infrared quantum cascade laser spectroscopy [PDF, 449KB]
9 March 2012, CMM-RS Potential for Characterization of the Properties of the Halogen-Bonded OC-Cl2 Complex, and a Comparison with Hydrogen-Bonded OC-HCl [PDF, 1.7MB]
23 February 2012, Wavelength-modulation-spectroscopy for real-time, in situ NO detection in combustion gases with a 5.2 μm quantum-cascade laser [PDF, 1.46MB]
University of Oxford 23 February 2012, Applications of QCLs in studies of chemical dynamics[PDF, 1MB]
Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser (APPLIED PHYSICS LETTERS, 2009) [PDF, 290KB]
Daylight Solutions Logo August 8, 2011 - Precision and Accuracy of Daylight Solutions Mode Hop-Free Lasers [PDF, 600KB]
Detecting CO2 isotopologues in the 4.4 µm region [PDF, 150KB]
Mid-infrared photonic crystal cavities in silicon
Quantum Cascade Laser Spectroscopy and Photoinduced Chemistry of Al-(CO)n Clusters in Helium Nanodroplets
University of Alberta Detection of benzene and toluene gases using a mid-infrared continuous-wave external cavity quantum cascade laser at atmospheric pressure [PDF, 476KB]
Real-time monitoring of benzene, toluene, and p-xylene in a photoreaction chamber with a tunable mid-infrared laser and ultraviolet differential optical absorption spectroscopy [PDF, 728KB]
Cornell NanoScale Science and Technology Facility Silicon waveguides and ring resonators at 5.5 µm [PDF, 442KB]
Rice University NO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy and external cavity quantum cascade laser [PDF, 500KB]
University of Alberta Jet-cooled infrared spectra of molecules and complexes with a cw mode-hop-free external-cavity QCL and a distributed-feedback QCL [PDF, 1.4MB]
University of Nottingham Application of External-Cavity Quantum Cascade Infrared Lasers to Nanosecond Time-Resolved Infrared Spectroscopy of Condensed-Phase Samples Following Pulse Radiolysis [PDF, 376KB]
Adelphi University - Dept of Physics Extremely sensitive detection of NO2 employing off-axis integrated cavity output spectroscopy coupled with multiple-line integrated absorption spectroscopy: 28 ppt of N2O
Enhancement of trace gas detection by integrating wavelength modulated spectra across multiple lines [PDF, 525KB]
Enhanced sensitivity for the detection of trace gases using multiple line integrated absorption spectroscopy (APPLIED OPTICS, 2009)
Absorption and wavelength modulation spectroscopy of NO2 using a tunable, external cavity continuous wave quantum cascade laser (APPLIED OPTICS, 2009)
Brookhaven National Lab Kinetic and Mechanistic Studies of Carbon-to-Metal Hydrogen Atom Transfer Involving Os-Centered Radicals: Evidence for Tunneling
Mechanism of the Formation of a Mn-Based CO2 Reduction Catalyst Revealed by Pulse Radiolysis with Time-Resolved Infrared Detection
Application of External-Cavity Quantum Cascade Infrared Lasers to Nanosecond Time-Resolved Infrared Spectroscopy of Condensed-Phase Samples Following Pulse Radiolysis