Tunable twin‐guide (TTG) laser diodes with metal‐clad ridge‐waveguide (MCRW) structure for coherent optical communications

Abstract

Tunable twin‐guide (TTG) laser diodes with metal‐clad ridge‐waveguide (MCRW) structure were developed for advanced coherent optical communication systems at 1.55 μm wavelength. The essential advantage of these lasers over previous devices is the simplified handling due to the inherent continuous tuning behaviour enabling the unambiguous wavelength control by only one tuning current. With 400 μm long devices, threshold currents around 50 mA, optical output power levels above 10 mW and tuning ranges around 1.2 nm (150 GHz) are achieved by maintaining the linewidth below 4 MHz. With an optimized design a maximum continuous tuning range of 2 nm has been obtained.

Wavelength Tunable Laser Diodes and Their Applications

“…8b) with spectrallinewidth below about 30 MHz [36]. For ridge-waveguide TTG lasers 4 MHz linewidth with tuning ranges up to 2 nm have been obtained [34]. TTG lasers exploiting the QC8E instead of the free carrier plasma effect are well suited for broadband FM modulation yielding a flat FM response up to more Besides the large tuning range, the simple tuning scheme, which is inherently continuous and requires only one single wavelength control current, reveals as a significant advantage in practice of the TTG lasers over the multi section DBR and DFB devices with their complex tuning behaviour [38].…”

“…8a [23,34,35]. This laser can be considered as a single mode DFB laser whose effective refractive index is tuned homogeneously along the laser axis by means of current It.…”