Abstract
We have characterized the spectral noise density and frequency modulation performance of an 8.5 micron quantum-cascade diode (QC) laser operating continuously at liquid nitrogen temperatures. The phase noise is measured by fixing the laser frequency in the half-height region of a molecular resonance and measuring the fluctuations in absorbance; these fluctuations are then accurately converted into measurements in the fluctuations of the absolute frequency. A Fourier analysis of the intrinsic spectral/phase noise show a 1/f2 dependence up to the measurement bandwidth limit of approx. 1 MHz. The laser linewidth is < 1 MHz when measured over several milliseconds. Servo locking schemes will be discussed with the implication that QC laser sources can be stabilized to a high degree. The frequency modulation performance of a QC laser has been measured and synchronous detection of f, 2f and 3f absorption signals (nitrous oxide at 8.5 μm) has been achieved with direct modulation of the injection current.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 11-22 |
| Number of pages | 12 |
| Journal | Proceedings of SPIE - The International Society for Optical Engineering |
| Volume | 3758 |
| State | Published - 1999 |
| Externally published | Yes |
| Event | Proceedings of the 1999 Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Processing Monitoring II - Denver, CO, USA Duration: Jul 19 1999 → Jul 20 1999 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering