excerpts of the thesis:

Background - low back pain is reported as over 70% in industrialized countries.

Results - low level laser therapy group have shown more significant results (p value <0.001) compared to control group managed with conventional therapy.

LASER

Low-level laser treatment (LLLT) is a treatment procedure which utilizes a solitary wavelength light source. Laser has the accompanying qualities: collimation – it has little bar dissimilarity over separation; union – the light waves are all in stage; and monochromicity – it has a solitary or tight band of a specific wavelength of light. The radiated laser light is noted for its high level of spatial and worldly coherence. Laser radiation and monochromatic light might adjust cell and tissue capacity .

The three fundamental components by which laser produce pain relieving impacts are accepted to be: animating endogenous opoids discharge, lifting torment limits, and adjusting the arrival of harmful go betweens,

The wavelengths of light utilized for LLLT fall into an "optical window" at red and NIR wavelengths (600–1070 nm).
Wavelengths in the reach 600–700 nm are utilized to treat shallow tissue, and more wavelengths in the extent 780–950nm, which infiltrate further, are utilized to treat more profound situated tissues. 

CONCLUSION

No side effects were noticed for LLLT throughout the study period. Hence LLLT is a viable option to treat acute radicular pain and there by arresting the promotion towards chronicity. 
LLLT reduces pain and disability in acute state and delay or prevents progression.