Dispersion-compensative optical assembly

An optical assembly comprising:

• a first grating device including a compensating grating with straight lines and equal line spacings and optically coupled to a fiber, the first grating device configured to:
• receive a light beam that includes an optical signal with a particular wavelength from the fiber;
• and
• change a propagation direction of the optical signal according to the particular wavelength of the optical signal;
• and
• a second grating device including a focusing grating with curved lines and unequal line spacings and positioned between the first grating device and a grating coupler, wherein the second grating device is positioned at an angle not parallel to the grating coupler, the second grating device configured to:
• receive the optical signal outputted from the first grating device;
• change the propagation direction of the optical signal according to the particular wavelength of the optical signal;
• and
• direct the optical signal onto the grating coupler,
• wherein the first grating device and the second grating device are configured to satisfy a plurality of configuration constraints that include:
• a relative displacement of the first grating device and the second grating device enables the second grating device to direct the optical signal onto the grating coupler;
• and
• after propagating through the second grating device, the optical signal is inputted to the grating coupler with an input angle that matches an optimal incidence angle configured for the particular wavelength on the grating coupler.

An optical assembly comprising:

• a first grating device including a compensating grating with straight lines and equal line spacings and positioned proximate a fiber, the first grating device configured to:
• receive a light beam that includes optical signals with different wavelengths from the fiber;
• and
• change propagation directions of the optical signals according to the respective wavelengths of the optical signals;
• and
• a second grating device including a focusing grating with curved lines and unequal line spacings and positioned between the first grating device and a grating coupler, wherein the second grating device is positioned at an angle not parallel to the grating coupler, the second grating device configured to:
• receive the optical signals outputted from the first grating device;
• change the propagation directions of the optical signals according to the respective wavelengths of the optical signals;
• and
• direct the optical signals onto the grating coupler,
• wherein the first grating device and the second grating device are configured to satisfy a plurality of configuration constraints that include:
• a relative displacement of the first grating device and the second grating device enables the second grating device to direct the optical signals with the different wavelengths onto the grating coupler;
• and
• after propagating through the second grating device, the optical signals converge and are incident on the grating coupler with different input angles that respectively match optimal incidence angles configured for the different wavelengths on the grating coupler.

An optical system comprising:

• a fiber configured to output a light beam that includes an optical signal with a particular wavelength;
• an optical assembly that includes:
• a first grating device including a compensating grating with straight lines and equal line spacings and positioned proximate the fiber, the first grating device configured to receive the light beam from the fiber and change a propagation direction of the optical signal according to the particular wavelength of the optical signal;
• and
• a second grating device including a focusing grating with curved lines and unequal line spacings and positioned between the first grating device and a grating coupler, wherein the first grating device and the second grating device are parallel and have the same dispersive properties and the second grating device is positioned at an angle not parallel to the grating coupler, the second grating device configured to receive the optical signal outputted from the first grating device, change the propagation direction of the optical signal according to the particular wavelength of the optical signal, and direct the optical signal onto the grating coupler, wherein the first grating device and the second grating device are configured to satisfy a plurality of configuration constraints that include:
• a relative displacement of the first grating device and the second grating device enables the second grating device to direct the optical signal onto the grating coupler;
• and
• after propagating through the second grating device, the optical signal is inputted to the grating coupler with an input angle that matches an optimal incidence angle configured for the particular wavelength on the grating coupler;
• and
• wherein the grating coupler is configured to couple the optical signal with the input angle to a waveguide on a silicon photonics device.