Attenuation-controllable micromachined <inline-formula><math altimg="none" display="inline" overflow="scroll"><mrow><mn>2</mn><mo>×</mo><mn>2</mn></mrow></math></inline-formula> optical switches using <inline-formula><math altimg="none" display="inline" overflow="scroll"><mrow><mn>45</mn><mtext>-</mtext><mi>deg</mi></mrow></math></inline-formula> micromirrors