Abstract

Tunable vertical-cavity surface-emitting lasers (VCSELs) are highly desirable in long reach reconfigurable wavelength division multiplexed passive optical network (WDM-PON) systems. As a colorless source, the widely tunable VCSEL can be utilized in applications including sparing, hot backup and fixed wavelength laser replacement for inventory reduction. A record continuous tuning of 102 nm has already been demonstrated for previous generation micro-electro-mechanical system (MEMS) VCSELs [1]. A small-signal modulation (S₂₁) bandwidth of 7.8 GHz with a high-contrast grating (HCG) VCSEL is reported only for 1550 nm [2]. In this work, a MEMS distributed Bragg reflector (DBR) is integrated to a 1550 nm Benzocyclobutene (BCB) encapsulated active VCSEL structure by means of surface micromachining. The InP-based half-VCSELs are specially designed for high speed application by lowering the RC-parasitics. For an essential reduction of capacitance-parasitic, the semiconductor is sidewise replaced by low-k material BCB. Wide tunability is realized by electro-thermal actuation of the MEMS DBR using an external heating current. The DBR consists of 11.5 layer-pairs of dielectric materials SiN_x/SiO_y deposited in a low-temperature plasma enhanced chemical vapor deposition (PECVD) chamber.

© 2015 IEEE