A tunable inter-stage matching circuit that can improve performance is described. The adjuster is moveable within the aperture, allowing an adjustment between the bracket and a cabinet member or a drawer member to which the adjuster is secured. The connecting waveguide includes a first material having a first index of refraction and a second material having a second index of refraction higher than the first index of refraction. The methods may further include forming a gate insulating layer on the first and second quantum well channel structures of the substrate and forming a gate electrode layer on the gate insulating layer.