Assembly of components having different coefficients of thermal expansion

An optical module, comprising:

• a first component comprising an optical component having a first coefficient of thermal expansion (CTE);
• a second component comprising a support component having a second CTE different from the first CTE;
• and
• a spacer, disposed between the first component and the second component, having a third CTE different from the second CTE, the spacer including:
• an annular body having opposing upper and lower surfaces disposed at opposing axial ends of the annular body,
• wherein the annular body defines a hole in a center portion of the annular body axially extending between the upper and lower surfaces of the annular body;
• and
• a mounting area disposed on the upper surface of the annular body for receiving the first component;
• wherein the mounting area and a lower surface of the first component are joined via an adhesive;
• wherein the second component includes a protrusion axially extending from an upper surface of the second component into the hole in the center portion of the annular body, such that a joint between the protrusion and the spacer is under compressive stress;
• wherein the first component, the protrusion, and the annular body define, within the hole in the center of the annular body, a first air gap disposed between the lower surface of the first component and the protrusion and surrounded by the annular body;
• and
• wherein the protrusion is adhered within the hole in the center portion of the annular body to define a second air gap disposed between the upper surface of the second component and the lower surface of the annular body.

A wavelength selective switch, comprising:

• a first component comprising an optical component having a first coefficient of thermal expansion (CTE);
• a second component comprising a support component having a second CTE different from the first CTE;
• and
• a spacer, disposed between the first component and the second component, having a third CTE different from the second CTE, the spacer including:
• an annular body having opposing upper and lower surfaces disposed at opposing axial ends of the annular body,
• wherein the annular body defines a hole in a center portion of the annular body axially extending between the upper and lower surfaces of the annular body;
• and
• a mounting area disposed on the upper surface of the annular body for receiving the first component;
• wherein the mounting area and a lower surface of the first component are joined via an adhesive;
• wherein the second component includes a protrusion axially extending from an upper surface of the second component into the hole in the center portion of the annular body, such that a joint between the protrusion and the spacer is under compressive stress;
• wherein the first component, the protrusion, and the annular body define, within the hole in the center of the annular body, a first air gap disposed between the lower surface of the first component and the protrusion and surrounded by the annular body;
• and
• wherein the protrusion is adhered within the hole in the center portion of the annular body to define a second air gap disposed between the upper surface of the second component and the lower surface of the annular body.