Ultra-narrow linewidth laser plays a very important role in the high-precision optical frequency transfer via optical fibers. We have designed and realized a compact portable laser system for transportable communication band ultra-narrow linewidth laser. Based on the method of topology optimization design, a stable optical board is developed. Designed and developed a series of small optical grade devices without exercise rules, making the optical system more stable. The optical system we designed is suitable for transportable ultra-narrow linewidth laser.
A measurement of sub-kilohertz laser linewidth is demonstrated by a recirculating self-heterodyne detection, in which the delay time is far less than the coherence time of the laser. The system parameters are optimized through theoretical analysis to improve the circulation rate of the beat signal. On this basis, we build a loss-compensated recirculating selfheterodyne interferometer with only a 2 km SMF-28 optical fiber spool. Thanks to the recirculating structure with an acoustic optical modulator (AOM), multi-group beat notes with high circulation rate can be measured simultaneously, which agree well with the theoretical analysis. By simulating and fitting the spectra of high-order beat notes with different delay times, the average linewidth with less statistical errors is obtained. The loss-compensated recirculating selfheterodyne method with short fiber can avoid single measurement error and almost neglect the influence of the broadening spectrum induced by the 1/f frequency noise, providing a powerful candidate for precise measurement of sub-kilohertz laser linewidth.
Utilizing the mechanism of cavity secondary resonance, we proposed a tunable hybrid optical filter combined band-pass spectral and low-pass noise filtering for femtosecond lasers. The experimental results shown that, by stabilizing the cavity length to different transmission peaks, the 3 dB bandwidths of the spectral filter can be tuned from 1.78 nm to 2.8 nm and the tunable cut-off frequency of the low-pass noise filter can be identified by their different attenuations which vary from 9.5 dB to 15.2 dB, of the relaxation oscillation in the laser relative intensity noise (RIN).
We demonstrate an optical frequency transfer over a 377 km-long fiber link using three bi-directional Erbium-doped fiber amplifiers (EDFAs) to compensate the fiber attenuation. Through active phase noise cancellation, we obtain a transfer instability of 2.2×10-14 at 1 s and 6.2×10-17 at 2000 s. The lasing effects induced by EDFAs are observed in the transfer link which reduce the gain performance of the EDFAs and deteriorate the stability of the signal. In the paper, the factors that may induce the lasing effects is discussed, specially, improper phase locking parameters may stimulate the lasing effects. The phase noise of the 377 km link and the transfer instability versus fiber lengths is also researched. This work makes a good foundation for our future research on long-distance optical frequency transfer.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.