LD and SLD Coupling Technology

Our business is optical fiber alignment. We can fiber-couple and package virtually any laser diode, SLD or photodiode in TO-can. 

We can make coupling to various types of optical fibers, but we focus predominantly on the most challenging coupling to the single-mode (SM and PM) optical fibers with the small core diameter.

Laser diode, SLD, and photodiode modules are thoroughly controlled at every production stage. We take care of cleanliness and ESD safety. Design of modules is being tested according to Telcordia GR-468-CORE.

Laser diodes and SLDs coupling

Our modules demonstrate high coupling efficiency with good thermal stability. The thermal stability of the module without active thermal stabilization is characterized by front-to-rear tracking error ER = 10 log[P(T)/P(25C)] where the temperature varies in a certain range (e.g. from - 40C to +85C), while the signal of the monitor photodiode is kept constant.

By thorough module design and special coupling optics we achieve the typical tracking error ER = 0.3 dB (i.e. coupling efficiency variation within +/-7%) for telecom wavelengths in the temperature range from -40C to +85C, while the standard value for commercial laser diode modules is ER = 0.8-1.0 dB.

Photodiodes

For optical fiber to photodiodes coupling we use 2 technologies

• Small back-reflection, e.g. R50 (i.e. return loss RL=50dB)
  Special coupling optics minimizes back-reflection to optical fiber. The absence of back-reflected signal improves the stability of laser sources in optical fiber line.

• Refractive-index Matching (RM)
  The space between the photodiode and optical fiber is filled with a special refractive index matching material that cancels reflection at optical fiber/air interface. This approach results in 4% larger photodiode responsivity. The RM photodiode modules demonstrate small PMD and excellent signal stability.