All-fiber bidirectional optical parametric oscillator for precision sensing

Abstract

We present the design and operation of an all-fiber, synchronously pumped, bidirectional optical parametric oscillator (OPO) for precision sensing applications. The fiber-based OPO (FOPO) generates two frequency combs with identical repetition rates but different carrier offset frequencies. A narrow beatnote was observed with full-width at half-maximum (FWHM) linewidth of <10 Hz when the two frequency combs were overlapped on a photodetector. The all-fiber design removes the need for free-space alignment and adjustment. In addition, an external delay line to overlap the two pulse trains in time on the detector is not needed since our unique design provides automatic delay compensation. We expect the novel FOPO to find important applications in precision measurements including rotation sensing with ultra-large sensing area and sensitivity.

Rotation Active Sensors Based on Ultrafast Fibre Lasers

“…However, in the demonstrated experimental settings, the central frequency of the beat-note drifted by tens of kHz over 30 s due to the environmental perturbations, including temperature fluctuations, or the splitting ratio alteration of the variable coupler. Even though Gowda et al [ 152 ] did not demonstrate rotation measurements, the presented gyroscope concept has high potential to reach high measurement sensitivity.…”

“…However, both methods for absolute measurements of require complex setup and high input energies. In bidirectional mode-locked lasers with identical repetition rates of counter-propagating generation, CEO frequency difference can be easily estimated from the RF spectrum [ 152 ].…”

“…Thus, in this work, intracavity polarisation state control and pump power variation allowed fine-tuning of the beat-note frequency, which corresponds to zero rotation [ 123 ]. This ‘rest’ beat-note (at zero rotation) refers to the beating of CEO frequencies of counter-propagating pulses [ 152 ]. Therefore, the fine-tuning of the ‘rest’ beat-note could be attributed to the CEO frequencies variation of both counter-propagating pulses.…”

“…The above-discussed bidirectional mode-locked fibre lasers feature complex nonlinear dynamics, involving interactions in gain media and collisions in material saturable absorbers [ 171 , 172 ]. A quite different approach for fibre laser cavity design was suggested by Gowda et al [ 152 ], which eliminates the complex dynamics in a gain medium that generally has a relatively long excited state lifetime. The gyroscope in this case presents an optical parametric oscillator (OPO) based on four-wave mixing in an optical fibre loop ( Figure 13 a).…”

Counter-rotating cavity solitons in a silicon nitride microresonator

“…The difference in effective detuning was controlled using the two AOM's and leads to a difference in repetition rate for the solitons. While there have also been recent demonstrations of bidirectional modelocked solid state [43] and fiber [44,45] laser cavities, a microresonator-based system could be highly compact and fully integrated onto a chip.In this Letter, we present a novel approach to generating counter-rotating trains of solitons in a single microresonator using a single pump laser without using frequency shifting devices by thermally tuning the microresonator. By tuning the relative pump powers in the two directions, we can control the repetition rate of the two soliton-modelocked pulse trains.…”