Tham khảo tài liệu 'micromechanical photonics - h. ukita part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 70 2 Extremely Short-External-Cavity Laser Diode Fig. . Deflection of a bimorph MC and internal stress due to temperature change where Mị EịIị rị Iị bt3 12 is the moment of inertia of i th layer hi is the distance between the center plane of the MC and that of the i th layer and rị is the radius of curvature of the i th layer of the MC and h1 h2 t 1 Í2 2 h2 h3 t2 ts 2 h1 h3 t1 2Í2 ts 2. At the interface between the two layers the normal strain of the materials must be the same. Therefore 1AT E 1 AT e22 Ề 2AT bi - Ề A ĩỀ Pr . Here r1 r2 r3 r very thin compared to length and we derive the curvature k 1 r by eliminating P1 P2 P3 from to . Note that the deflection d at the free end of the MC from the curvature k is d for l r. Finally the tip deflection of the MC by thermal strain due to the mismatch between the thermal coefficient of the expansion is d 0 B where A 3ATl2 E1E2t1Í2 a1 a2 t1 t2 E2E3t2t3 a3 t2 t3 E1E3t1Í3 1 a3 t 1 2t2 t3 B 2E1E2t1t2 2t2 3t 1 2 2t2 2E2E3t2t3 2t2 3t2t3 2t2 I 077. 77 4. í - i 2 I I I i-j J. I A-i-- - I I 77244 I 77244 I TP 2 4 2E 1E 3t1t3 2t1 6t2 2t3 6t1t2 6t213 3t1t3 E 1 tỊ E212 E313- Designs for Related Problems of an ESEC LD 71 Thickness of a semiconductor film mm Fig. . Numerical simulation of the tip deflection versus semiconductor thickness by a temperature increase of 100 C for a metal-dielectric bimorph structure MC for two types of semiconductor materials Table . Properties of materials used in photothermal MCs material thermal expansion coefficient 10-6 K-1 young s modulus 1010 Nm-2 300 K refractive index 830 nm refractive index m Au SisN4 InP GaAs Figure shows the result of numerical simulation by the material parameters shown in Table . More than X 2 deflection is possible for less than thick semiconductor MC with 100 C temperature increases for both GaAs and InP .
