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A passively Q-switched Yb:YAG/Cr:YAG laser pumped by a photonic-crystal surface-emitting laser (PCSEL) was developed. Yb:YAG crystal was cryogenically cooled by liquid nitrogen at 77 K. Excellent Gaussian beam profile ( M = 1.02) and high slope efficiency of 58% were demonstrated without using a coupling optics between a laser material and PCSEL. [ABSTRACT FROM AUTHOR]

The applications of surface-emitting lasers, in particular vertical-cavity surface-emitting lasers (VCSELs), are currently being extended to various low-power fields including communications and interconnections. However, the fundamental difficulties in increasing their output power by more than several milliwatts while maintaining single-mode operation prevent their application in high-power fields such as material processing, laser medicine and nonlinear optics, despite their advantageous properties of circular beams, the absence of catastrophic optical damage, and their suitability for two-dimensional integration. Here, we demonstrate watt-class high-power, single-mode operation by a two-dimensional photonic-crystal surface-emitting laser under room-temperature, continuous-wave conditions. The two-dimensional band-edge resonant effect of a photonic crystal formed by metal-organic chemical vapour deposition enables a 1,000 times broader coherent-oscillation area, which results in a high beam quality of M2 ≤ 1.1, narrowing the focus spot by two orders of magnitude compared to VCSELs. Our demonstration promises to realize innovative high-power applications for surface-emitting lasers. [ABSTRACT FROM AUTHOR]

Introduction: The rotator cuff has a characteristic structure, in that one surface faces articular cartilage and another faces bursa. This structure may produce differences in the healing process between the rotator cuff and other tendons. We investigated the spontaneous healing process of a surgically created supraspinatus tendon tear in rabbits. Materials and Methods: A transverse, full-thickness tear of the supraspinatus tendon was created and its healing examined. Results: A tear of 12 mm was not repaired within 3 weeks. With a tear of 5 mm, reparative tissue gradually encroached into the defect from the bursal side, and the tear united from the bursal side to the articular side by 12 weeks. The healing rates (width of reparative tissue/width of the tendon x 100%) were 32.2%, 52.4%, 58.0%, 88.9%, and 93.8% at 1, 2, 3, 6, and 12 weeks, respectively. The reparative tissue had continuity to the epitenon of the bursal side. Immunohistochemical study showed that at week 1, type III collagen was detected in the reparative tissue and the cutting ends, and the expression gradually decreased. On the other hand, the expression of type I collagen in the reparative tissue was weak at week 1 and increased until week 3. PCNA-positive cells were observed in the reparative tissue. Conclusion: These results show that the origin of the reparative tissue is the epitenon, and from the bursal side rather than the articular side. This model is very useful for the investigation of the remodeling process of an acute rotator cuff tear. [ABSTRACT FROM AUTHOR]