  The reflectivity $R (\omega)$ of both the $ab$ plane and the c axis of two
single crystals of La$_{1.875}$Ba$_{0.125-y}$Sr$_{y}$CuO$_4$ has been measured
down to 5 cm$^{-1}$, using coherent synchrotron radiation below 30 cm$^{-1}$.
For $y$ = 0.085, a Josephson Plasma Resonance is detected at $T \ll T_c$ = 31 K
in $R_{c} (\omega)$, and a far-infrared peak (FIP) appears in the optical
conductivity below 50 K, where non-static charge ordering (CO) is reported by
X-ray scattering. For $y$ = 0.05 ($T_c$ = 10 K), a FIP is observed in the
low-temperature tetragonal phase below the ordering temperature $T_{CO}$. At
1/8 doping the peak frequency scales linearly with $T_{CO}$, confirming that
the FIP is an infrared signature of CO, either static or fluctuating.
