The femtoWrite process is used to locally change the index of refraction of glasses. The femtoWrite process relies on the use of femtosecond laser pulses, tightly focused to a point inside a glass substrate. At the focal point, the light intensity is so great that the energy is locally deposited though nonlinear absorption. Yet, since the pulse is short and its energy content limited, the glass almost immediately re-solidifies. With the proper laser parameters, one can control the local structure of the re-solidified material and modify its physical properties.

Translume uses software to direct high-precision stages that move the substrate sending the lasers beam on a path inside the glass. The result: local micro-structuring action is turned into a highly controlled three-dimensional manufacturing process for writing glass waveguides.

For several years, short pulse laser technology has offered the promise of becoming the first truly 3-dimensional integrated photonics-manufacturing platform. Until now, optical performance parameters and yield issues have perplexed researchers and limited the grand vision of multiple passive and active devices in serial and parallel configurations. 

The main optical parameters characterizing a waveguide are size, delta n, optical loss, and birefringence. The size and the delta n (difference in index of refraction between the waveguide core and its cladding) of a waveguide are related to its ability to support guided propagation of light of a given wavelength in a single mode or multimode fashion. These parameters also govern losses and the minimum bending radius of curvature. (A waveguide with a weak delta cannot turn sharply without introducing substantial optical loss.)

Translume has developed manufacturing processes to produce low loss waveguides. Presently we specify our waveguide intrinsic losses to be below 0.2 dB/cm @ 1550-nm. 

Translume standard waveguides are shaped to be single-mode at 1550-nm. The mode field diameter matches that of SMF-28 fiber.

Numerous passive waveguide structures such as splitters, couplers, delay lines, MZI, and long period gratings have been demonstrated using the femtoWrite process. Active devices such as VOA, thermo-optic switches, thermo-optics filters, and gain blocks have also been demonstrated.

Waveguides manufactured with the femtoWrite process are quite resilient. Our waveguides can be exposed to elevated temperatures for long periods of time. Please click on the popup windows to the right for details.