Slotted Fabry-Perot tunable laser offers reduced cost and complexity

Unlike distributed-Bragg-reflector (DBR) lasers requiring custom Bragg gratings and multiple growth steps, a novel slotted Fabry-Perot (SFP) laser manufactured using a single growth-fabrication process and standard lithography offers wide tunability, high side-mode suppression ratio (SMSR), nanosecond switching, and narrow linewidth at a significantly lower cost and with potentially higher yield than competing monolithic tunable lasers.

Developed and characterized by researchers from Tyndall National Institute (Cork, Ireland) and Trinity College Dublin and Dublin City University (both in Dublin, Ireland), the SFP laser uses commercially available multiple-quantum-well wafers that are processed into ridge-waveguide lasers. Multiple reflective etched slots are formed in the same step as the waveguiding ridge and do not enter the active region. The slots divide the device into three separate regions that can be electrically controlled, causing interference effects and refractive-index changes sufficient to achieve single-mode lasing in 25 modes, with linewidths of 200 to 700 kHz. Applied currents up to 60 mA are sufficient to create 25 channels over the 100 GHz dense wavelength-division-multiplexed grid, with average relative intensity noise below -135 dB/Hz for five measured channels—comparable to fabrication-intensive and more expensive DBR lasers. Contact Kai Shi atkaishi@eeng.dcu.ie.

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