The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Diode Lasers with Optical Feedback and Optical Injection: Applications in Metrology

Markku Vainio

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S1 at Helsinki University of Technology (Espoo, Finland) on the 31st of March, 2006, at 12 noon.

Overview in PDF format (ISBN 951-22-8101-5)   [759 KB]
Dissertation is also available in print (ISBN 951-22-8100-7)

Abstract

The visible red near 633 nm is an important spectral region in length metrology. Iodine-stabilized He-Ne (HeNe/I2) laser stabilized on the hyperfine spectrum of the R(127)11-5 transition is one of the most used optical frequency standards for practical realization of the definition of the meter. Furthermore, the existence of much stronger transitions in the vicinity of R(127)11-5 motivates to develop new frequency standards based on tunable diode lasers. Both to improve already existing optical frequency standards and to develop new ones, precise absolute frequency measurements of the used iodine transitions are needed. At present, such measurements can be performed using an optical femtosecond frequency comb generator. In this thesis, diode laser systems for absolute frequency measurements with the optical frequency comb generator have been developed. In order to improve diode laser performance to the required level, optical feedback and optical injection locking techniques have been used.

To facilitate the absolute frequency measurements of the HeNe/I2 laser, an optical amplifier has been constructed. The amplifier can be reliably operated over several hours with very low phase noise, and it has been successfully used in absolute frequency determination of an iodine-stabilized He-Ne laser. For absolute frequency determination of various iodine transitions in the vicinity of 633 nm, a laser spectrometer has been realized. The new spectrometer design has been made particularly for good frequency accuracy and reproducibility. It combines, through injection locking, good beam quality of a microlens-coupled diode laser with high spectral quality of a stable external-cavity diode laser. The spectrometer uses wavelength modulation technique for locking the laser frequency to an iodine hyperfine component. For this reason, the modulation transfer properties of injection-locked diode lasers have been investigated in detail. In particular, suppression of intensity modulation and reproduction of frequency modulation have been considered, for the first time, in terms of master-slave frequency detuning. Also the conversion of the master laser frequency modulation into slave laser intensity modulation has been considered. In addition to spectroscopy, the results are useful in optical communications.

This thesis consists of an overview and of the following 5 publications:

  1. M. Vainio, M. Merimaa, Y. Sidorin, M. Kuittinen, and E. Ikonen, Miniaturized transmission grating laser at 1.55 µm with 128-nm tuning range, IEEE Photonics Technology Letters, Vol. 15, No. 7, pp. 990-992 (2003).
  2. M. Vainio, M. Merimaa, and E. Ikonen, Iodine spectrometer based on a 633 nm transmission-grating diode laser, Measurement Science and Technology, Vol. 16, No. 6, pp. 1305-1311 (2005).
  3. M. Vainio, M. Merimaa, and K. Nyholm, Modulation transfer characteristics of injection-locked diode lasers, Helsinki University of Technology, Metrology Research Institute Report, 29/2005, 14 pages.
  4. M. Vainio, M. Merimaa, and K. Nyholm, Optical amplifier for femtosecond frequency comb measurements near 633 nm, Applied Physics B: Lasers and Optics, Vol. 81, No. 8, pp. 1053-1057 (2005).
  5. M. Merimaa, K. Nyholm, and M. Vainio, MIKES frequency comb generator and absolute frequency measurements of iodine-stabilized lasers, Proceedings of the 12th International Conference on Metrology, Lyon, France, 20-23 June 2005, 6 pages.

Keywords: diode lasers, external cavity, injection locking, optical frequency measurements, frequency comb

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© 2006 Helsinki University of Technology

Last update 2011-05-26