In our quest to demonstrate electron directional coupling, the coheren
t tunneling of electrons between two electron waveguides, we have inve
stigated split-gate dual electron waveguide devices. With the structur
e biased in a ''leaky'' electron waveguide configuration we have carri
ed out extensive observations of one-dimensional (1D) to two-dimension
al (2D) tunneling between a waveguide and a neighboring two-dimensiona
l electron gas. These tunneling spectroscopy experiments have provided
the first glimpse of the one-dimensional density of states of a 1D el
ectronic system. We have also carried out experimental observations of
1D to 1D tunneling between two electron waveguides. Demonstrating ele
ctron directional coupling will still require the development of a new
generation of ultrashallow heterostructures with sharp confining pote
ntial barriers.