Well-sampled optical light curves of 50 gamma-ray bursts (GRBs) with plateau features are compiled from the literature. By empirical fitting, we obtained the parameters of the optical plateaus, such as the decay slopes (α 1 and α 2 ), the break times (T b ), and the corresponding optical fluxes (F b ) at the break times. The break time of optical plateaus ranges from tens of seconds to 10 6 seconds, with a typical value about 10 4 seconds. We have calculated the break luminosity, and it mainly ranges from 10 44 erg s −1 to 10 47 erg s −1 , which is generally two or three orders of magnitude less than the corresponding break luminosity of the X-ray afterglow plateaus. We reanalyzed the optical plateaus and also found that a significantly tighter correlation exists when we added the isotropic equivalent energy of GRBs E γ,iso into the L b,z − T b,z relation. The best fit correlation is obtained to be L b,z ∝ T −0.9 b,z E 0.4 γ,iso . We next explored the possible correlations among L b,z , T b,z and E p,i , and found there is also a tight correlation between them, which takes the form of L b,z ∝ T −0.9 b,z E 0.5 p,i . We argue that these two tight L b,z − T b,z − E γ,iso and L b,z − T b,z − E p,i correlations are more physical, and it may be directly related to radiation physics of GRBs. The tight correlations are possible to be used as standard candles.

The model of non-ballistic jet motion Gong (2008) provides a simple explanation for inward jet motion and bent jets. Recently, evidence for such non-radial motion has accumulated rapidly, and more complicated morphologies have appeared. However, the ballistic plus precession model is likely to hold in most samples of jet motion. In this paper, we discuss the relationship between the ballistic and non-ballistic models of jet motion. This relationship suggests that the interaction of ejectors with ambient matter can produce knots at different stages of evolution, and hence different separations to the core. Also, as a jet precesses, knots produced between the core and the deceleration radius result in a spiral pattern, as predicted by the model of ballistic plus precession. Knots generated at the deceleration radius display non-radial motion, such as a bent jet or the oscillation of the ridge line. We develop the first non-ballistic model and we highlight the following four features. (i) The model provides a numerical simulation for the production of a multiknot for a precessing jet. (ii) It fits the precession behaviour of multiknot and interprets the oscillation of ridge lines, such as S5 1803+784. (iii) It gives a unified interpretation to the bent jet, which is applicable to both a multiknot and a single knot. (iv) The problem of the very large numbers of observed outward motions, rather than inward motions, is addressed in a new way.