No abstract

No abstract

No abstract

The fin effectiveness can be enhanced by; (i) using high thermal conductivity material e.g., aluminium, copper, (ii) higher ratio of surface area to the perimeter of the fins, (iii) thin and closely placed fins for natural convection rather than thick fins, and (iv) smooth airflow path within the fins.

No abstract

Laser interaction with doped crystals exhibiting photon-photon and photon-phonon coupling has been focused on recently. In pretext, here we report the spectral and temporal profile interaction of two lasers excitation through various phases of Eu3+: BiPO4 crystals. We reveal that spectral-temporal profile interaction of hybrid signals (coexisting fluorescence and spontaneous four-wave mixing) are dressed by nested and cascade processes of two-photons (two-phonon). Such interaction comes from thermal phonon constructive and phase transition phonon destructive dressing. The spectral and temporal (profile) interactions are interrelated and reduced by about 2-times due to two-photon nested dressing in contrast to the interaction through the sum of each laser excitation. In contrast to a single laser, spectral (Fano)-dip interaction reduces by 2-times due to two-photon destructive dressing coupling. Moreover, thermal phonon dressing at 300K exhibits 3-times more extensive temporal interaction than that at 77K. The phase transition phonon dressing for a half hexagonal and half low-temperature monoclinic phase is about 1.5-times longer than that of the pure hexagonal phase of Eu3+: BiPO4. These results may help to understand the spectral-temporal relationship in the fields of nonlinear and quantum optics.

No abstract

We compare the atomic coherence time of doped ion crystals, i.e., BiPO4: Eu3+, YPO4: Eu3+, YPO4: Pr3+, and Y2SiO5: Pr3 + crystals. Such atomic coherence time is controlled by crystal field splitting (CF-splitting) and optical (photon and phonon) dressing. Compared with the other doped ion crystals, BiPO4: Eu3+ exhibits the longest coherence time. By controlling thermal phonon, phase-transition phonon, broadband or narrowband excitation, and fluorescence (FL) or spontaneous four-wave-mixing ratio (S-FWM), a superior atomic coherence time of up to 10 ± 0.6 ms is achieved in the pure hexagonal (0.5:1) phase of BiPO4: Eu3+. Furthermore, the relationship between TAT-splitting and spectral Autler–Townes (SAT)-splitting was investigated. This superior atomic coherence time has potential applications in quantum memory devices.