John loves to study engineering at work and in his free time. We suspect he also dreams about electron-hole pairs and resonant frequencies at night. When forced to take a break from study, John also likes sampling random combinations of nuts and berries, not sure what’s up with that, but we respect it. He also is working on brewing his own kombucha and beer in his closet, so we’ll see how that turns out. He also enjoys climbing up walls. Anyway, that’s pretty much all you need to know about John other than that he’s a nerd, but maybe you picked up on that already…
Multiwavelength adaptive optic systems can experience phase errors when corrections measured at one wavelength are applied to others. Such errors originate from several sources, but poor optical coating design can play a major role since the phase dependence of any coating varies greatly with wavelength, angle, and thickness. To address these errors, a multilayer coating design is proposed where the effective electric field penetration depth into the coating is similar at all design wavelengths. Using this method, a two-wavelength coating is designed for 1070 and 1550 nm and compared to a standard two-wavelength high-reflectivity coating consisting of stacked Bragg reflectors. The standard stacked Bragg reflector design induces up to 173.0 nm of phase error across the wavelength band that reflects off the more deeply buried part of the multilayer. Alternatively, the two-wavelength equal field penetration design maintains a high reflectivity of 99.999%, while only inducing phase variations of 28.6 nm for both target wavelengths.
An uncooled detector has reached the thermodynamic temperature fluctuation limit, such that 98% of its total noise consisted of phonon and photon fluctuations of the detector body. The device has performed with a detectivity of 3.8\texttimes109 c m H z/W, which is the highest reported for any room temperature device operating in the long-wave infrared (λ∼8-12\textmum). The device has shown a noise-equivalent temperature difference of 4.5 mK and a time constant of 7.4 ms. The detector contains a subwavelength perforated absorber with an absorption-per-unit-thermal mass-per-area of 1.54\texttimes1022 k g -1 m -2, which is approximately 1.6–32.1 times greater than the state-of-the-art absorbers reported for any infrared application. The perforated absorber membrane is mostly open space, and the solid portion consists of Ti, S i N x, and Ni layers with an overall fill factor of ∼28%, where subwavelength interference, cavity coupling, and evanescent field absorption among units induce the high absorption-per-unit-thermal mass-per-area. Readout of the detector occurs via infrared-absorption-induced deformation using a Mach–Zehnder interferometry technique (at λ=633n m), chosen for its long-term compatibility with array reads using a single integrated transceiver.