  Miniature semiconductor lasers have attracted a large amount of interest
owing to their potential as highly integrated components in photonic circuits
or in sensors. Particularly, microdisk lasers exploiting whispering gallery
modes have been regarded as an important candidate because of their relatively
small footprint and low threshold. However, it has been challenging for
microdisk to operate under single mode operation and to lase in a preselected
mode. We report subwavelength microdisk resonators suspended in air with
connecting bridges and propose a simple method using the number and symmetry of
bridges to enhance or reduce wave confinement in the whispering gallery cavity.
Moreover, a suitable choice of bridges increases the quality factor of
microdisks compared to microdisks resonator without bridges. Using this method,
we demonstrate single mode lasing of preselected modes at telecommunication
wavelength.
