Huawei Technologies Co., Limited

Yang Ren

Feng Han

Zhiping Jiang

Huijun Liu

Maozeng Li

Vien Van

Methods and devices that provide a variable-bandwidth optical filter with frequency tuning are disclosed. A universal variable bandwidth optical filter architecture is disclosed, based on microring resonators that can vary both operation wavelength and bandwidth with no extra complexity relative to conventional wavelength tunable filters. The filter architecture provides a universal filter design for any arbitrary shape of filter response, such as second-order, fourth-order, sixth-order, and so on. The filter characteristics&#x2014;insertion loss, in-band ripple, and out-of-band rejection level&#x2014;may be maintained over the bandwidth tuning range. There is no need for extra heaters to tune the filter's operating bandwidth, as the same heaters used to tune the filter frequency can be used to tune filter bandwidth. The device can be used as an add/drop filter.

Variable bandwidth microring optical filter device and method with frequency tuning

A method and an apparatus for determining a structured query language (SQL) execution plan are provided to optimize determining of the SQL execution plan and improve execution efficiency of the SQL execution plan. The SQL execution plan corresponds to at least one relation table. During an Niteration, the method includes obtaining a first iteration parameter generated after a first plan tree is executed on the at least one relation table during an (N&#x2212;1)iteration, where N is a natural number greater than 1, establishing a second plan tree according to the first iteration parameter, and determining the first plan tree or the second plan tree as the SQL execution plan when a difference between the second plan tree and the first plan tree is not greater than a first threshold.

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Edmonton, Canada

Yang Ren