Theory of single-mode laser instabilities

Journal Article · Tue Jan 01 04:00:00 EST 1985 · J. Opt. Soc. Am. B: Opt. Phys.; (United States)

DOI:https://doi.org/10.1364/JOSAB.2.000084· OSTI ID:5824429

Hendow, S T; III, Sargent M

We use the semiclassical strong-signal theory of the laser to predict and explain the onset of side-mode buildup in lasers with one oscillating mode. Two general categories are considered: one for which the side modes and the oscillating mode all have the same wavelength and the other for which they have different wavelengths. The treatments include an arbitrary amount of inhomogeneous broadening. Our approach unifies the treatments of the side-mode instabilities presented earlier and extends them to handle standing waves in addition to the previously treated running waves. We write the field and the population matrix elements as Fourier series in the adjacent mode beat frequency. This approach has been used extensively in both multimode laser theory and saturation spectroscopy. This technique coincides with linear stability analyses used by others, provided that our beat frequency includes a contribution that is proportional to the Complex side-mode gain. We give a solution that allows for detuned operation along with its simpler, centrally tuned special case. The connection with saturation spectroscopy clearly reveals that the side-mode instabilities require side-mode gain. For the single-wavelength case, nonlinear anomalous dispersion is also required. The side-mode gain and dispersion result from both inhomogeneous broadening and population pulsations. The lowest instability thresholds occur when both of these mechanisms play a role. The approach can also be used to treat instabilities in optical bistability by substituting the appropriate equation of state for the strong-mode intensity and by changing the sign of the absorption coefficient. In homogeneously broadened, standing-wave lasers, we show that multiwavelength instabilities depend strongly on the position of the medium in the cavity.

• Research Organization: Litton Guidance and Control Systems, MS 19, 5500 Canoga Avenue, Woodland Hills, California 91365
• OSTI ID: 5824429
• Journal Information: J. Opt. Soc. Am. B: Opt. Phys.; (United States), Journal Name: J. Opt. Soc. Am. B: Opt. Phys.; (United States) Vol. 2:1; ISSN JOBPD
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
ABSORPTION
AMPLIFICATION
ANALYTICAL SOLUTION
DIFFERENTIAL EQUATIONS
ENERGY
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EQUATIONS OF MOTION
FOURIER ANALYSIS
GAIN
GAS LASERS
HELIUM-XENON LASERS
INSTABILITY
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LINE BROADENING
MATHEMATICS
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NUMERICAL ANALYSIS
OPTICAL DISPERSION
OPTICAL MODES
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OSCILLATION MODES
PARTIAL DIFFERENTIAL EQUATIONS
PULSATIONS
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STANDING WAVES
THRESHOLD ENERGY
TUNING
WAVELENGTHS