Spectral broadening in continuous-wave intracavity Raman lasers

Abstract

Spectral broadening of the fundamental field in intracavity Raman lasers is investigated. The mechanism for the spectral broadening is discussed and the effect is compared in two lasers using Raman crystals with different Raman linewidths. The impact of the spectral broadening on the effective Raman gain is analyzed, and the use of etalons to limit the fundamental spectral width is explored. It was found that an improvement in output power could be obtained by using etalons to limit the fundamental spectrum to a single narrow peak. 9810-9818 (2012). 20. J. J. Zayhowski, "The effects of spatial hole burning and energy diffusion on the single-mode operation of standing-wave lasers," IEEE J. Quantum Electron.

Spatial and Spectral Effects in Continuous-Wave Intracavity Raman Lasers

“…The convolution R(ω) * F (ω) of the Raman and fundamental line shapes determines the spectral gain for the Stokes modes [38], and the overall gain is thus determined by the overlap integral of that spectral gain with the Stokes line shape S(ω). For experimentally-measured line shapes, g e can be calculated [10], and will always be less than g 0 . As a guide, for fundamental and Stokes fields of similar width to the Raman line width we have g e ≈ g 0 /3, and to achieve g e > 0.9g 0 we need the fundamental and Stokes line width to be less than 1/20 of the Raman line width.…”

“…An axiallypeaked Stokes field provides a higher output coupling loss for lower-order fundamental transverse modes (which are more axially compact) and provides higher output coupling loss at the spectral line center of the fundamental field than in the wings of the fundamental spectrum. These factors can lead to intracavity Raman lasers operating with degraded spatial [8], [9] and spectral properties [10] compared to their fundamental laser counterparts.…”

“…Passive crystals that can be measured [6], [11]. The transverse mode profiles [8], [12], [13] and spectral profiles [5], [8], [10], [12] of both the fundamental and Stokes fields must be measured as a function of pump power, as they are affected by the laser dynamics and developing aberrated thermal lenses. Characterizing these intracavity thermal lenses [8], [11], [13]- [16] allows prediction of the TEM 00 mode sizes of the resonator.…”

Q-Switched Yb:YAG/YVO4 Raman Laser

“…According to the Raman output performance mentioned above, the limitation of first-Stokes Raman conversion efficiency and average output power may be attributed to two factors. Firstly, both the broad gain bandwidth of Yb:YAG crystal induced broad fundamental emission spectrum and the SRS process induced broadening influence on the fundamental field will reduce the effective Raman gain [23]. Secondly, the competition between the two fundamental emission peaks around 1029 nm and 1049 nm affects the output laser performance.…”

A Thresholdless Tunable Raman Nanolaser using a ZnO–Graphene Superlattice

“…The spectral broaden may be the result of many factors such as the new frenquency component arising from the nonlinear effect, and the spectrally-varying loss to the fundamental 5 field in the stimulated Raman scattering process, which is interpreted in Supplementary Text S1. [28,29] A firstprinciple Maxell-Bloch formulation of light-matter interaction are used to inverstigate the dynamics of nanolasers through quantum electrodynamics, [30] and the dynamics of Raman nanolaser in graphene-based superlattice are to be investigated via this approach in the future work.…”