**5. Active adjusting techniques**

In optical packaging laboratories, fiber-chip coupling is performed within sub-micrometer precision in order to get a high coupling efficiency between the optical devices. Precision op‐ tical experiments depend upon reliable position stability. Vibration sources in and around the work are depicted in figure 9. Floors carry vertical vibrations in the range of 10 Hz to 30 Hz caused by people, traffic, seismic activity, and construction work. Tall buildings sway up to a meter in the wind, at frequencies from 1 Hz to 10 Hz. Machinery generates vibrations up to 200 Hz. Optical benches and their associated vibration isolating support systems pro‐ vide a rigid and virtually vibration-free working surface that holds the components of an ex‐ periment in a fixed relative position. The legs support the tabletop: Air suspension mechanisms reduce practically all vibrations by two orders of magnitude.

**Figure 9.** Influence of vibrations for micro positioning.

also dangerous for the life of the laser diode if it comes into contact with the with the fi‐ ber end. But there is only one low-priced device on the market, which makes this device

The tolerances for lateral and longitudinal fixing of the fiber taper in front of the opto-elec‐ tronic circuit or OEIC are shown in figure 7 and figure 8. Both graphs show the distance in micrometers at the x-axis and a relative intensity of the coupling efficiency between the ta‐ pered fiber and the OEIC. You can see in figure 7 that within 2 micrometers the intensity will not be lower than 0.5 dB of the maximum intensity. For the longitudinal direction the

Please remember: it is easier by a factor of four to perform the optical coupling in longitudi‐

In optical packaging laboratories, fiber-chip coupling is performed within sub-micrometer precision in order to get a high coupling efficiency between the optical devices. Precision op‐ tical experiments depend upon reliable position stability. Vibration sources in and around the work are depicted in figure 9. Floors carry vertical vibrations in the range of 10 Hz to 30 Hz caused by people, traffic, seismic activity, and construction work. Tall buildings sway up to a meter in the wind, at frequencies from 1 Hz to 10 Hz. Machinery generates vibrations up to 200 Hz. Optical benches and their associated vibration isolating support systems pro‐ vide a rigid and virtually vibration-free working surface that holds the components of an ex‐

very comfortable for use in small and very reasonably priced modules.

tolerance is much greater: in this case 8μm, which can be seen in figure 8.

**Figure 8.** Z-axis with higher tolerance of 8µm.

426 Optoelectronics - Advanced Materials and Devices

**5. Active adjusting techniques**

nal direction in comparison to the lateral direction.

In order to align a fiber optically to another component, one has to move either the fiber, the component or both. Three linear and three angular motions are necessary to describe fully the motion and position of a solid body in space. The figure below identifies the six degrees of freedom using the common Cartesian frame of reference. When each of these degrees of freedom is singularly constrained by a hardware device, the device is labelled kinematic.

The device used to move a component in the linear x, y, or z direction is a translation stage. The device used to move a component in the angular θx, θy, or θz direction is a rotation stage.

Actuators are used to move the component on a translation stage to its desired position. There are three basic types of actuators used with precision stages: manual drives, stepper motor drives, and piezoelectric transducers. Manual drives and stepper-motor drives can move components over long distances, constrained only by the size of the manual drive or, in the case of stepper motors, the length of the lead screw. Piezoelectric transducers can move components over very short distances with nanometre precision. The range and reso‐ lution of the various drives and stage technologies is shown in figure 10 below.

**Figure 10.** Translation ranges of available micro mechanical stages and screw systems.

For fiber-chip-alignment mostly all six degrees of freedom must be moved. Several commer‐ cial six axes motion systems have been developed with translatoric resolution of better then 0.02μm and angular resolution of better then one arc second. As an example, a mechanical/ piezoelectric driven system with six degrees of freedom is shown in figure 11. Software tools are also included for automated coupling for one fiber and fiber arrays. Most of the software applications are available as a Labview virtual Instrument (VI).

tances promise very good RF-features up to 100GHz bandwidth. Today this progress allows the introduction of batch processing for the optical and electrical part of the optoelectronic packaging of OEICs. This benefit opens the market for high volume production of devices for optical communications systems that allows cost effective production of low budget

Opto-Electronic Packaging http://dx.doi.org/10.5772/51626 429

The progress in mechanical precision of the FC-bonds makes it possible to align one or mul‐ tiple optical fibers direct to OEICs. Firstly, the OEIC will be FC-bonded as shown in figure 14. In the next step the fibers are inserted into V-grooves, fabricated by an anisotropic wet etching of the silica substrate. After insertion, the fiber must be fixed mostly by UV-hard‐ ened glue. Here more than 100 fibers can be arranged passively in one single fabrication step to the OEIC. An example of the connection of four lasers to an array of single mode fibers is

In the next development step additional electrical amplifiers, multiplexers, modulators etc. can also be located on the substrate. This kind of hybrid integration is called optical mother‐ board or photonic lightwave circuit (PLC) depicted in figure 16. This type of integration is the most promising technique today for reaching an adequate price level of optical commu‐

products for the consumer market.

**Figure 12.** Flip-chip set-up.

**Figure 13.** Flip-chip self-alignment.

**6.2. Optical board technology**

shown in photograph 15.

nications products for the consumer market.

**Figure 11.** Six axes Nano-positioning system.
