Highly Birefringent D-Shaped Micro-Fiber Device for High-Repetition-Rate-Difference Single-Cavity Dual-Comb Generation

An ultra-high birefringent D-shaped microfiber device with birefringence over 4 × 10
⁻²
and insertion loss down to 0.2 dB is proposed and experimentally demonstrated. When the all-fiber-compatible device gets applied into a linear single-short fiber laser cavity, dual-comb with large repetition rate up to 431 MHz and high repetition-rate-difference over 250 kHz are realized. The single-cavity laser exploits high birefringence of the device to boost building of asynchronous combs through the polarization-multiplexing method. The achieved repetition-rate-difference is several orders of magnitude larger than previous works, revealing the potential to enhance acquisition rate of certain dual-comb measurement application scenarios.