As deep ultra-violet (DUV) wavelength optical systems progress towards higher numerical aperture (NA), at least some
of the lens surfaces in the system approach almost complete hemispherical shape and some of the lens surfaces have very
high angle of incidence (AOI) requirements. The antireflection (AR) coating designs for such lens surfaces must address
intensity apodization due to coating thickness nonuniformity and polarization purity. We present some of the recent
results in the area of DUV coatings that highlight these challenges and demonstrate production capability.
We demonstrate the integration of vertical-cavity surface- emitting laser (VCSEL) arrays with Si-dummy chips for potential use in short-distance parallel optical interconnects. An 8 X 8 flip-chip bonded InGaAs VCSEL array was successfully modulated at data rates up to 0.8 Gbit/s/channel, corresponding to an aggregate data transmission capacity in excess of 50 Gbit/s. A 2 X 4 VCSEL array was indirectly flit-chip bonded to a Si substrate via a transparent glass carrier and package- limited data rates of 0.4 Gbit/s/channel were achieved. The large signal modulation bandwidth of these devices exceeded 2 Gbit/s. The electrical driving characteristics of the devices were found to be compatible with 3.3 V CMOS technology.
Spectroscopic work is reviewed which focuses on the microscopic mechanism of gain in ZnSe-based quantum well (QW) lasers, under optical and electrical injection, respectively. Excitonic processes are rather distinct at cryogenic temperatures in the strongly quasi-2 dimensional case of a ZnCdSe QW. More strikingly, recent studies on the room temperature diode lasers show that electron-hole pairwise Coulomb correlations remain relevant in this case as well.