AGC Inc., a Tokyo-based world-leading manufacturer of glass, chemicals and high-tech materials, has announced the development of a glass package that is ideal for encapsulating edge-emitting laser diode (LD) chips. Since both sides of this product are polished surfaces, the light emitted from the LD chip can be efficiently extracted without additional parts such as a prism mirror. In addition, by adding proprietary solder for hermetic sealing developed by AGC, the product simplifies customers’ manufacturing process and contributes to extending the life of their laser products. This glass package is currently in the prototyping phase and AGC is aiming for mass production.
Most of the current LD chips are “edge-emitting types.” Besides, most of the package has a window only on the top face. So a separate prism mirror is necessary to extract light from the LD chip upward, making it difficult to reduce costs and minimize the package ((1) in Fig. 2). Another current solution is to bond the polished window on the side hole of the package. Since bonded with a sealing material, it is difficult to attach the window at the precisely right angle so as to project light in the target direction ((2) in Fig. 2).
AGC has developed a new glass package to help resolve these issues (Fig. 1). This product is box-shaped with an aperture on one side and has the following advantages.
- Without additional parts or bonding mirror surface windows, the emitted light is led to a designed optical path without refracting.
- Excellent air tightness because windows are integrated without using any sealing material.
- Since the opposite surface of the polished window is also transparent, the user can see and check the inside of the package even after sealed.
Furthermore, by adding proprietary solder for hermetic sealing developed by AGC to the frame surface of the aperture, the process of sealing with the ceramic substrate can be completed simply by heating and pressing in the air. This eliminates the need for large-scale deoxidization equipment for the customer. In addition, this proprietary solder is soft enough to reduce the thermal stress generated due to a difference of CTE between the package and window. This helps to prevent deterioration in airtightness from cracks at the interface after thermal cycle testing. As a result, this also contributes to extending the life of the laser package.