The invention relates to a microfluidic dye laser including a pump light source configured to provide light having a pump light wavelength. The microfluidic dye laser also includes an elastomer substantially optically transparent at the pump light wavelength and at a microfluidic dye laser wavelength. A microfluidic channel configured to accept a fluidic dye is defined in the elastomer. An optical grating is formed in a single mode 3D waveguide in the microfluidic channel in order to provide a single mode microfluidic dye laser light as output in response to illumination with light from the pump light source. In another aspect, the invention features a method of tuning a wavelength of a microfluidic dye laser light by mechanically deforming the elastomeric laser chip to change the grating period in the optical cavity.