Tritone substitution: D7 can be replaced by G#7 (a tritone away). Both chords share the same tritone between the 3rd and 7th, resolving to the same tonic.
The augmented 11th forms a tritone with the root and avoids the close clash that a perfect 11th creates with the 3rd. The combination of major 3rd, minor 7th, and #11 matches the Lydian dominant scale.
Application
Lydian harmony
Jazz and fusion
Film scoring
Voicing & structure
Root position
v1D(D4)Bass
root
v2F#(F#4)M3from D
v3A(A4)m3from F#
v4C(C5)m3from A
v5E(E5)M3from C
v6G#(G#5)M3from E
Harmony
Compatible scales
All chord tones are contained in these scales — use them for improvisation.