Optical systems configured for both changing the length of a laser pulse and operating as an optical isolator are disclosed. In some embodiments, optical isolation is achieve contemporaneously with laser pulse expansion or compression by using a grating based compressor or expander as one of the polarization elements of the optical isolator. In some embodiments, optical isolation is achieved contemporaneously with laser pulse expansion or compression by using a mode converter and a Bragg fiber as one of the polarization elements of the optical isolator. In some embodiments, a sub-wavelength polarizer including magnetic garnet is included in the optical isolator.