InP-In
1-xGa
xP
1-zAs
z-InP (

) double-heterojuncfion (DH) lasers emitting at

m (77 K) have been fabricated by constant-temperature liquid-phase epitaxy (LPE). The crystal-growth process is described and compared to previous work on visible spectrum (

-Å) In
1-xGa
xP
1-zAs
zdouble-heterojunction lasers. Emission spectra are presented for the near-infrared quaternary DH lasers. In particular, the observation of cavity oscillations in the low-level spontaneous-emission spectra allows the determination of the index dispersion quantity over a wide wavelength range. Finally, these In
1-xGa
xP
1-zAs
zDH lasers are operated in an external-grating cavity. Such operation permits tunable, narrow-linewidth laser emission and provides information concerning radiative-recombination processes. Comparisons are made to earlier work on external-grating operation of visible-spectrum (

-Å) In
1-xGa
xP
1-zAs
zDH lasers.