Highly strained In0.66Ga0.34As/In0.30Al0.70As multiquantum wells (MQWs) are successfully grown on (001)InP substrates by moleular beam epitaxy. Good crystal quality in the strained MQWs is confirmed by clear excitonic peaks and sharp photoluminescence spectra. Intersubband absorption at a wavelength as short as 3.1 &mgr;m was obtained for the first time in uniformly Si‐doped strained MQWs.