This study demonstrates etch profile engineering of InP, In1-xGaxAs1-yPy, and In0.53Ga0.47As heterostructures results from adding H-2 to standard Cl-2/Ar inductively coupled plasma-reactive ion etching chemistries. Etch rate curves of bulk InP, In1-xGaxAs1-yPy, and In0.53Ga0.47As show a general parabolic trend as a function of the H2 component of the Cl-2/Ar/H-2 ratio. Three distinct etching profiles of InP/InGaAsP layers were realized by varying the Cl-2/Ar/H-2 ratio. Highly anisotropic profiles result for Cl-2/Ar/H-2 ratios between 2/3/1 and 2/3/2. Waveguiding structures fabricated using this technology are presented with a loss as low as 2 dB/cm. An InP racetrack resonator with a quality factor (Q) > 8000 is also presented.