MULTI-WAVELENGTH SURFACE EMITTING LASER ARRAY

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Massively integrated parallel optical devices are becoming important for use in future parallel optical fiber communication systems, optical interconnects, parallel optical recording and so on. Vertical cavity surface emitting lasers (VCSELs) have been attracting much interest for optical interconnects as well as for hihg speed parallel optical data links because of their low threshold and ease in optical coupling to fibers. A 2-D array configuration will increase the connection density in optical interconnects. In addition, if multi-wavelength VCSEL arrays are available for wavelength division multiplexing (WDM) interconnects, functionalities such as wavelength routing can be expected. A potential application of VCSELs for WDM systems is multi-wavelength laser arrays.The lasing wavelength of VCSELs is determined primarily by the length, the equivalent refractive index and the lateral size of the cavity. Among them, the lasing wavelength predominantly depends on the cavity length. For … More example, a 1% variation of layr thickness over a wafer produces a fairly large wavelength change of 10nm at a nominal wavelength of 1mum. If we are able to locally control the layr thickness, we can form multi-wavelength 2-D arrays as well as compensate for the nonuniformity of the lasing wavelength across the wafer. A nonplanar MBE growth is proposed as a way of local control of layr thickness for multi-wavelength VCSEL arrays.In this work, we present a novel technique of on-wafer wavelength control of VCSELs using nonplanar metalorganic chemical vapor deposition (MOCVD). The fabrication process is the same as that of standard VCSELs except that the substrates are patterned prior to the growth. Multi-wavelength VCSEL arrays can be fabricated by changing the size of the circular pattern. Low threshold 3*3 multi-wavelength VCSEL arrays were demonstrated by using this technique. The proposed method might be useful to realize muti-wavelength VCSEL arrays with an extremely large wavelength span. Also, we will be able to compensate for the wavelength nonuniformity of VCSELs across a large wafer by using this technique. Less