Femtosecond laser written diamond waveguide excitation of the whispering gallery modes in a silicon microsphere

Laser-Inscribed Diamond Waveguide Resonantly Coupled to Diamond Microsphere

“…|t 2 | is correlated with the coupling efficiency, which can be estimated with (√2λ)/(π2ωo), where ωo is the 1/e 2 width of the MFD of the beam inside the diamond WG [34]. Based on our experimental parameters, the coupling efficiency is estimated as ~3.3% [25]. As a result, Qext is calculated to be in the order of 10 5 .…”

“…As a result, the maximum measured Q-factor is 1.6 × 10 5 , comparable with the previous findings of monolithic diamond microsphere WGMs with Q-factor of 2.4 × 10 7 [4], and 4.5 × 10 4 [26] limited by the respective material losses and the spectral resolution of our measurement setup. As demonstrated in [25], the diamond WG provides better light coupling and propagation in TM mode, thus yielding a higher Q-factor. There are several factors affecting the total achievable Q-factor, as shown in:…”

“…The WG exhibited a 12.4 dB insertion loss at a 1550 nm wavelength, with a mode field diameter (MFD) of 16 µm × 20 µm, elongated in the vertical axis, which was measured with a similar WG characterization setup as in [24]. The cross-sectional microscope image and near-field mode profile of the optimum WG are shown in Figure 1 [25].…”

A 33.2 W High Beam Quality Chirped-Pulse Amplification-Based Femtosecond Laser for Industrial Processing

“…Therefore, femtosecond laser processing has ultra-high precision and spatial resolution with strong universality. For example, the femtosecond laser can realize the machining of brittle materials (such as ceramics, transparent dielectric materials, and silicon wafer) without cracks [10,11], as well as the fine machining of flexible materials (such as biological tissue and flexible printed circuits) [12,13] and super hard materials (such as diamond and tungsten carbide) [14,15].…”