Gain Flattening Approach to Physical EDFA for 16 × 40 Gb/s NRZ-DPSK WDM Optical Communication Systems

Abstract

We are using different approaches to gain flattening in EDFAs without using additional components; i.e., gain flattening filter, dispersion shift fiber, periodic gratings, etc. By using gain flatten approach 3, it is possible to achieve the transmission of sixteen channels at 40 Gb/s wavelength division multiplexing (WDM) over a transmission distance of 490 km by single-mode fiber and dispersion-compensating fiber at a span of 70 km with channel spacing of 200 GHz. We observed the bit error rate less than 10 −9 and power of received signal more than −5 dBm with NRZ-DPSK format.

Independent and mixed transmission of 166.5 Gb/s PM‐8QAM and 222 Gb/s PM‐16QAM Nyquist‐wavelength division multiplexed superchannel for long‐haul metro network

“…Designing a flat spectral gain EDFA is possible by controlling the doped fiber length. 33 Generally, an EDFA consists of a length of Er 3+ -doped fiber of typically 10-30 m. On varying EDFA physical length from 10 to 50 km, we realized that minimum acceptable BER remains under 4 × 10 −3 till 25 km length only. From 25 km onward, EDFA maintains no acceptable BER and also causes gain saturation.…”

“…But the second EDFA is a fixed gain inline optical amplifier, placed along with an optical fiber, which compensates the total link loss by offering gain of attenuation α (dB/km) × fiber length (km). Designing a flat spectral gain EDFA is possible by controlling the doped fiber length 33 . Generally, an EDFA consists of a length of Er 3+ ‐doped fiber of typically 10–30 m. On varying EDFA physical length from 10 to 50 km, we realized that minimum acceptable BER remains under 4 × 10 −3 till 25 km length only.…”

Improvisation of Gain and Bit-Error Rate for an EDFA-WDM System using Different Filters

“…(4) WDM system is difficult to implement because of the dependent on wavelength of EDFA gain spectrum and it does not amplify the wavelength equally (5). Although EDFA systems are still needed to have equalized gain spectrum order to obtain similar signal to noise ratio and uniform output power (6). Various methods are there in designing a flat spectral gain of EFDA, by controlling the pumping power and length of fibre (7), by using a proper notch filter, or by acousto-optic tunable filter (8).…”

“…Three parts it is divided into are flat in pass band; outside the band it is zero; Chebyshev filters may be digital or analog filters having more passband ripple or steeper roll-off or stopband ripple than the Butterworth filter. With the ripples in the pass band, chebyshev can minimize the error between actual and idealized filter (6). Pass band ripple inheritance in chebyshev have a smoother response in pass band and irregular response in stop band are preferable for few applications.…”

Gain flatness of EDFA in WDM systems

“…In aWDM system, the EDFA does not necessary amplify thewavelength of the channels equally. EDFA [2] in a WDMsystem are often required to have equalized gain spectrain order to achieve uniform output powers and similar signal to noise ratios. There are several methodsin designing a flat spectral gain of EDFA such as by controlling the doped fiber length and the pump power, proper choosing of optical notch filter'scharacteristic, by using an acousto-optic tunablefilter and by employing an inhomogeneously broadened gain medium.In this paper the gain flatness of EDFA is achieved by controlling the doped fiber length and the pumppower for a given input power of-26dBm and a desired output power of more than 8dBm.…”