Progress in design and development of anti-guiding vertical cavity surface emitting laser at 850 nm: Above 50 Gb/s and single mode

Abstract

Design of the oxide-confined vertical cavity surface emitting laser (VCSEL) with anti-guiding AlAs-rich core has recently attracted a lot of attention. Lack of the waveguiding core increases the oscillator strength of the VCSEL mode, allows the ultimate optical confinement (“λ/2 design”) and reduces dramatically the optical power accumulated in the VCSEL mesa in the regions outside of the oxide aperture. We consider basic differences of conventional and antiwaveguiding VCSEL and address optical modes in the device. Both Joule heat and heat generated by the free carrier absorption of the optical mode in the doped semiconductor layers and their impact on the refractive index profile are considered. We show that for typical regimes of the VCSEL design and operation absorption-induced heat exceeds by several times the Joule heat while the shape of the generated heated domains strongly differ. Modeling shows that current increase results in an increase in spectral separation of the fundamental and high-order transverse optical modes. Selection of the fundamental mode persists upon increase in injection current up to 10 mA at 5 µm aperture diameter. We report on data transmission experiments up to 160 Gb/s using single mode antiwaveguiding VCSELs.