We demonstrate a PM-NALM fiber laser utilizing a 3x3 coupler. While a 2x2 coupler causes no phase bias between counter-propagating lights in the NALM, the 3x3 coupler can generate a phase bias (2μ3) in the NALM without an additional nonreciprocal phase shifter. As a result, this 3x3 coupler-based NALM laser requires less than 2 times pump power for the mode-locking initiation compared to the 2x2 PM-NALM laser with a similar repetition-rate and configuration. The minimum rms relative-intensity-noise (RIN) is only 0.0048% integrated from 10 Hz to 1 MHz offset frequency, which is one of the lowest RINs demonstrated from free-running mode-locked lasers so far.
We propose an electric field sensor using a cholesteric liquid crystal (CLC) Fabry-Perot etalon and a broadband optical source. The CLC cell consists of glass substrates, polyimide layers, electrodes, and CLC layer. There is a threshold behavior for CLC cell and no change in the transmitted wavelength occurs until a threshold value. The threshold value is 0.8 V/μm for fabricated CLC cell in this experiment. The transmitted or reflected wavelength from the CLC Fabry-Perot etalon depends on the applied electric field. The valley wavelengths of the transmitted light from the CLC device are linearly increased from 1303 nm to 1317 nm as the applied electric field to the CLC device is increased from 0.8 V/μm to 1.9 V/μm.
We constructed a standard measurement setup for polarization mode dispersion (PMD) based on Jones matrix eigen-analysis method. We measured a differential group delay of a 1 m-long polarization maintaining fiber (PMF) and evaluated the measurement uncertainty to be less than 0.6 %. As a transfer standard for PMD, we fabricated mode-coupled PMD artifacts by concatenating the 50 PMF sections with random birefringent axis orientation. Using the standard setup, we certificated the PMD values of the three PMD artifacts to be 0.0884 ps, 0.977 ps, 1.541 ps with the standard uncertainty of 0.4 fs, 16 fs, 23 fs, respectively.
An anti-reflection coated GaAlAs laser diode was used as a gain medium in a mode-locked fiber laser gyroscope to obtain stable mode-locked optical pulses without gain competition. The time intervals between the pulses could be measured with much improved accuracy using an electronic counter. The rms noise equivalent rotation rate was 3.4 deg/hr/(root)Hz and the long-term drift was less than 200 deg/hr.
A mode locked fiber laser gyroscope (MLFLG)  has a laser cavity formed with a fiber amplifier with a planar mirror at one end and a Sagnac loop interferometer at the other end, as shown in figure 1. The Sagnac interferometer functions as a loop mirror, and a phase modulator in the interferometer is used to modulate the reflectivity of the loop mirror.