Browse over 10,000 Electronics Projects using the Page Numbering provided at the bottom of each Page.

Controlling the S7500 CW Tunable Laser

Controlling the S7500 CW Tunable Laser

This document explains the general principles of operation of Finisar’s S7500 tunable laser. It provides a high-level description of the circuitry needed to control the S7500, as well as the control algorithms running on that circuitry.

Finisar’s patented tunable laser, the Modulated Grating Y-branch (MG-Y) laser, is based on a conventional distributed Bragg reflector (DBR) laser. The tuning range of a DBR laser is however limited to ~1 THz (~8 nm), which means a single DBR laser can not cover the full C- or L-band. In order to extend the tuning range, the single grating reflector of the DBR laser is replaced by a combination of two modulated grating (MG) reflectors.

The operation of the MG-Y laser is based on the Vernier effect. The two modulated grating reflectors have a comb-shaped reflectivity spectrum. The combs have slightly different peak separations, such that only one pair of peaks overlap at any time. Both reflections are combined using a multi-mode interference (MMI) coupler.

 

Top