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Silicon photonic waveguide resonators, such as microring resonators, photonic crystal waveguide cavities, and Fabry–Perot resonators based on the distributed Bragg reflectors, are key device components for silicon-based photonic integrated circuits (Si-PIC). For the Si-PIC with high integration density, the device footprints of the conventional photonic waveguide resonators need to be more compact. Inverse design, which is operated by the design expectation and different from the conventional design methods, has been investigated for reducing the photonic device components nowadays. In this paper, we inversely designed the silicon photonic waveguide reflectors for two target wavelengths: one is 1310 nm and the other is 1550 nm. The silicon photonic waveguide reflectors have reflectance of 0.99993 and 0.9955 for the wavelength of 1310 nm and 1550 nm each with 5-μm-long reflectors. Also, we theoretically investigated Fabry–Perot resonators based on the inversely designed photonic waveguide reflectors. Q factors of the Fabry–Perot resonators have been calculated to be 1.3 × 105 for the wavelength of 1310 nm and 2583 for the wavelength of 1550 nm. We have expected that the inversely designed photonic waveguide reflectors and their applications for the Fabry–Perot resonators can be utilized for compact passive/active device components such as wavelength filters, modulators, and external cavity lasers.

Tumoral calcinosis is a rare syndrome characterized by massive subcutaneous soft tissue deposits of calcium phosphate near the large joints. It is more prevalent in patients with chronic kidney disease undergoing dialysis. A 57-year-old woman was referred to our pain clinic with the complaint of severe pain in the left buttock and lateral hip. The patient had been suffering from chronic kidney disease for 10 years and had been undergoing peritoneal dialysis over the past 5 years. The patient's symptom was initially suspected to be of lumbar origin at the L5 level and a left L5 transforaminal epidural block was performed, but without success. Re-evaluation of the physical examination revealed severe tenderness over the left greater trochanter and piriformis muscle. On ultrasonographic evaluation, multiple mass-like lesions in the left buttock were observed. About 30 mL of fluid was aspirated from the cystic lesions, followed by 30 mL mixture of 0.08% levobupivacaine and triamcinolone 40 mg injected into the bursa under ultrasound guidance, which brought pain relief. Trochanteric bursitis was thought of as the cause of the symptoms. The patient was diagnosed with tumoral calcinosis based on the past medical history, simple plain radiographs, and hip magnetic resonance imaging (MRI). We diagnosed a case of greater trochanteric pain syndrome due to tumoral calcinosis related to chronic kidney disease in a patient whose symptoms had initially been considered to be radiating leg pain caused by lumbar spinal disease. We report our experience of symptomatic improvement following the repeated ultrasound-guided aspiration of calcific fluid and the injection of a mixture of local anesthetic and steroid.