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Characterization of a 10.3-microm pulsed DFB quantum cascade laser
1Electrical and Computer Engineering Department, University of Alberta, 9107-116 Street, Edmonton, AB, Canada T6G 2V4. alytkine@ualberta.ca
Summary
This study characterizes a 10.3-microm distributed-feedback quantum cascade laser for gas detection. Output parameters like beam divergence and frequency tuning were measured, crucial for high-sensitivity ammonia and ethylene sensing applications.
Area of Science:
- Optoelectronics and Laser Technology
- Spectroscopy and Sensing
Background:
- Quantum cascade lasers (QCLs) are vital for mid-infrared applications.
- Distributed-feedback (DFB) QCLs offer wavelength selectivity for targeted molecule detection.
- High-sensitivity gas sensing requires precise characterization of laser parameters.
Purpose of the Study:
- To measure and analyze the output characteristics of a 10.3-microm DFB QC laser.
- To evaluate the laser's suitability for high-sensitivity detection of ammonia and ethylene.
- To provide essential data for optimizing gas sensing systems utilizing this laser.
Main Methods:
- Characterization of laser beam divergence using an infrared imaging camera.
- Measurement of laser frequency tuning rates via an air-spaced Fabry-Perot interferometer.
- Analysis of laser output parameters as a function of injection current, temperature, and pulse repetition rate.
Main Results:
- Measured laser beam divergences of 1.2 mrad (fast-axis) and 1.4 mrad (slow-axis), increasing with injection current.
- Quantified frequency tuning rates with respect to temperature (-8 x 10⁻² cm⁻¹K⁻¹), current (-7 x 10⁻² cm⁻¹A⁻¹), and pulse repetition rate (-9 x 10⁻⁴ cm⁻¹kHz⁻¹).
- Observed a linear frequency decrease with pulse duration (10⁻² cm⁻¹ns⁻¹) and a decreasing frequency chirp rate for longer pulses.
Conclusions:
- The characterized DFB QC laser exhibits parameters suitable for high-sensitivity gas detection.
- Understanding beam divergence and frequency tuning is critical for sensor design and performance.
- The laser's tunable properties and chirp characteristics are important considerations for spectroscopic applications.
