Fiber-based Optical Parametric Amplifier Research Articles

Ultrafast Spectral Tuning of a Fiber Laser for Time-Encoded Multiplex Coherent Raman Scattering Microscopy

Coherent Raman scattering microscopy utilizing bioorthogonal tagging approaches like isotope or alkyne labeling allows for a targeted monitoring of spatial distribution and dynamics of small molecules of interest in cells, tissues, and other complex biological matrices. To fully exploit this approach in terms of real-time monitoring of several Raman tags, e.g., to study drug uptake dynamics, extremely fast tunable lasers are needed. Here, we present a laser concept without moving parts and fully electronically controlled for the quasi-simultaneous acquisition of coherent anti-Stokes Raman scattering images at multiple Raman resonances. The laser concept is based on the combination of a low noise and spectrally narrow Fourier domain mode-locked laser seeding a compact four wave mixing-based high-power fiber-based optical parametric amplifier.

Analysis of quasi-phase-matched optical parametric amplification in hollow-core fibers using analytical static electric field solutions

Nonlinear fiber laser sources offer new and attractive ways of achieving agile wavelength tunability. We previously modeled a quasi-phase-matched, pressurized xenon-filled, hollow-core fiber-based optical parametric amplifier where numerically solved electrostatic fields were applied across the fiber via patterned electrodes [Opt. Express 27, 11962 (2021)10.1364/OE.420075]. Here, we present analytical expressions that describe the spatial variations of the applied electrostatic fields that result from three distinct electrode patterns that span the space of manufacturing difficulty. These analytical expressions show good agreement with numerical results and are incorporated into nonlinear optical modeling to rapidly prospect a broad parameter space for optimal design based on frequency conversion efficiency.

Analysis of quantum noise of a gain-saturated fiber-based optical parametric amplifier based on an equivalent input noise model

A theoretical approach to evaluate quantum noise in gain-saturated fiber-based optical parametric amplifiers (OPAs) is presented. An equivalent input noise model that considers quantum noise is introduced, and an approximate expression of the saturated gain is presented to obtain the analytical formulas of the probability density function and the variance of signal fluctuations. Using this approach, the noise figure of gain-saturated OPAs can be analytically evaluated.

A two-stage optical parametric amplifier for femtosecond fiber laser generation at 920 nm

We demonstrate a cascaded, two-stage, fiber-based optical parametric amplifier (OPA) in which the signal pulses are generated in the first stage via spontaneous degenerate four-wave mixing (DFWM) mechanism and subsequently are used as the seed pulse for the stimulated DFWM in the second stage. A compact femtosecond fiber laser provides the pump pulse with 220-fs duration at 20-MHz repetition rate. Large-mode area (LMA) photonic crystal fibers (PCFs) with zero dispersion wavelength at 1054 nm and a dispersion slope of 0.20 ps/km/nm2 provide the parametric gain. Pulses with 2-mW average power in spectral range from 850 to 1000 nm are obtained from the first-stage OPA, and they are further amplified to 23.4 mW in the second stage OPA, corresponding to 10.7-dB parametric gain. The output pulse duration and spectral bandwidth are closely related to the temporal delay between the signal and pump pulses in the second stage. With an optimized time delay, pulses with >1 nJ energy and <200 fs duration are obtained at the spectral range from 850 to 1000 nm.

Nonlinear pulse compression in a gas-filled multipass cell.

We present an efficient method for compressing sub-picosecond pulses at 200W average power with 2mJ pulse energy in a multipass cell filled with different gases. We demonstrate spectral broadening by more than a factor of five using neon, argon, and nitrogen as nonlinear media. The 210fs input pulses are compressed down to 37fs and 35GW peak power with a beam quality factor of 1.3×1.5 at a power throughput of >93%. This concept represents an excellent alternative to hollow-core fiber-based compression schemes and optical parametric amplifiers (OPAs).

Ultrabroadband fiber optical parametric amplifier pumped by chirped pulses Part 2: sub-30-fs pulse amplification at high gain

We report numerical investigations on ultrashort pulse amplification with high gain in a fiber-based optical parametric amplifier pumped by a broadband chirped pulse. The amplifier has been tailored for ultrabroadband amplification with an analytical model and has key features to overcome gain narrowing and pulse distortion, which are usually observed in ion-doped fiber amplifiers. By combining chirped pump and signal pulses in a fiber, we highlight the possibility to amplify sub-30-fs pulses with standard ultrafast technologies.

Kerr nonlinearity mitigation in 5 × 28-GBd PDM 16-QAM signal transmission over a dispersion-uncompensated link with backward-pumped distributed Raman amplification.

We present experimental and numerical investigations of Kerr nonlinearity compensation in a 400-km standard single-mode fiber link with distributed Raman amplification with backward pumping. A dual-pump polarization-independent fiber-based optical parametric amplifier is used for mid-link spectral inversion of 5 × 28-GBd polarization-multiplexed 16-QAM signals. Signal quality factor (Q-factor) improvements of 1.1 dB and 0.8 dB were obtained in the cases of a single-channel and a five-channel wavelength-division multiplexing (WDM) system, respectively. The experimental results are compared to numerical simulations with good agreement. It is also shown with simulations that a maximum transmission reach of 2400 km enabled by the optical phase conjugator is possible for the WDM signal.

All-Optical Tunable Multitap Microwave Photonic Filter Enabled by Fiber Optical Parametric Amplifier

We propose and experimentally demonstrate an all-optical tunable microwave photonic filter (MPF) based on single pump fiber-based optical parametric amplifier (OPA). The delay-line structure is achieved with a spool of dispersion-compensating fiber and a simple time-delay-compensating element. Owing to the idler generation during the OPA process, the frequency responses of 2-tap, 4-tap, and 8-tap MPFs are experimentally achieved by one, two, and four signal laser sources, respectively. Thus, ~50% reduction on the number of laser sources is accomplished. The tunability of the filter transfer function can be achieved through either continuously tuning the wavelength spacing of the signals or changing the total dispersion value.

160-Gb/s NRZ-DQPSK optical transmission system employing QC-LDPC code

A quasi-cyclic low-density parity check (QC-LDPC) code is constructed by an improved stability of the shortest cycle algorithm for 160-Gb/s non-return zero differential quadrature phase shift keying (NRZ-DQPSK) optical transmission system with the fiber-based optical parametric amplifier (FOPA). The QC-LDPC code with stability of the shortest cycle reduces the bit error ratio (BER) to 10-14 and restrains the error floor effectively.

Fiber-based optical parametric amplif ier for 40-Gb/s NRZ-DPSK signal transmission system employing QC-LDPC codes

In this letter, we investigate quasi-cyclic low-density parity-check (QC-LDPC) codes in a 40-Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signal transmission system based on a fiber-based optical parametric amplifier (FOPA). A constructed algorithm of QC-LDPC codes according to the optimizing set of shift values on the circulant permutation matrix (CPM) of the basis matrix is proposed. Simulation results prove that the coding gain in the encoded system can be realized at 10.2 dB under QC-LDPC codes with a code rate of 5/6 when the bit error rate (BER) is 10-9. In addition, the error-floor level originating from the uncoded system is suppressed.

Fiber optical based parametric amplifier in a highly nonlinear fiber (HNLF) by using a ring configuration

A four-wave mixing (FWM) effect in a fiber-based optical parametric amplifier (FOPA) is reported. The novelty in the setup used is a ring cavity as opposed to the commonly used method of linear cavity. This reduces the required pump power, P p, for the amplification of the signals and also the generation of the idlers. The achieved gain for signal amplification is about 30 dB with a P p of 25 dBm. It has a flat gain response within range of 22 nm from 1570 nm to 1592 nm, with an average value of 28 dB within the 3 dB region. The average conversion efficiency is approximately −5 dB, with a peak value of −4 dB within the 2 dB region, with a range of 24 nm from 1576 nm to 1600 nm.

Design of Fiber-Optical Parametric Amplifiers by Genetic Algorithm

Genetic algorithm is adopted to give an automatic design scheme for fiber-based optical parametric amplifiers (FOPAs). Main steps of the optimization process and discussion about this algorithm are presented. The results show that present FOPA has more than 300-nm flat bandwidth with a central wavelength of 1500 nm and a gain ripple of less than 0.3 dB. Meanwhile, fluctuation in zero-dispersion wavelength of fibers is taken into consideration and its influence is briefly analyzed.

Amplification of WDM signals in fiber-based optical parametric amplifiers

We demonstrate for the first time, experimentally, the performance of fiber-based optical parametric amplifiers in wavelength-division-multiplexed (WDM) applications. Both a 3 /spl times/ 10 Gb/s and a commercial 7 /spl times/ 2.5 Gb/s WDM system are investigated together with the parametric amplifier. Limitations due to pump depletion and four-wave mixing are quantified. Measurements showing the performance in terms of power penalty and gain versus input-output signal power are presented.

Fiber-based optical parametric amplifiers and their applications

An applications-oriented review of optical parametric amplifiers in fiber communications is presented. The emphasis is on parametric amplifiers in general and single pumped parametric amplifiers in particular. While a theoretical framework based on highly efficient four-photon mixing is provided, the focus is on the intriguing applications enabled by the parametric gain, such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion. As these amplifiers offer high gain and low noise at arbitrary wavelengths with proper fiber design and pump wavelength allocation, they are also candidate enablers to increase overall wavelength-division-multiplexing system capacities similar to the more well-known Raman amplifiers. Similarities and distinctions between Raman and parametric amplifiers are also addressed. Since the first fiber-based parametric amplifier experiments providing net continuous-wave gain in the for the optical fiber communication applications interesting 1.5-/spl mu/m region were only conducted about two years ago, there is reason to believe that substantial progress may be made in the future, perhaps involving holey fibers to further enhance the nonlinearity and thus the gain. This together with the emergence of practical and inexpensive high-power pump lasers may in many cases prove fiber-based parametric amplifiers to be a desired implementation in optical communication systems.