SOA preamp performance: theoretical modeling

Transcription

1 SOA preamp performance: theoretical modeling ene Bonk, Dora van Veen, Vincent Houtsma, Bell Labs Ed Harstead, member Fixed Networks CTO January

2 eceiver Model for SOA+Filter+PIN / APD Analytical x model for SOA+filter+PIN and APD (modified from G. Agrawal, fiber-optic communication systems ) Different noise contributions included Shot noise (signal, SOA-ASE (both polarization), dark current) Thermal noise of TIA and electronic amplifier noise APD: excess noise from multiplication process SOA: signal-ase and ASE-ASE beat noise Extinction ratio of signal is 6dB SOA: power independent and time independent small-signal gain and noise figure APD: fixed multiplication factor and excess noise ectangular-shaped filters with insertion loss TIA and electronic amplifier noise for PIN and APD receivers assumed to be identical for all receiver types TIA and Si/Ge APD (M=12, F excess = 3.22) modeled according to SiFotonics contributions pan_3ca_1_0916.pdf BE calculated including all noise contributions 2

3 Parameter for eceiver Model for SOA+Filter+PIN / APD Parameter Value APD/PIN Quantum Efficiency 0.7 Signal Wavelength 1270nm Noise Factor of Electrical Amplifier 2 Load esistor of TIA 150Ω Electrical Bandwidth 18.75GHz for 25Gbit/s operation SOA Gain 17dB Device Temperature 300K Dark Current 60nA BE Threshold 1E-3 Si/Ge and InAlAs APD Multiplication Factor M 12 Si/Ge APD Excess Noise Factor F M = (according to SiFotonics, see pan_3ca_1_0916.pdf) InAlAs APD Excess Noise Factor F M = Extinction atio at x 6dB 3

4 4x25G OLT receiver sensitivity: TDM co-existence, λ0 How much receiver sensitivity benefit (measured at ) does the SOA+PIN implementation bring relative to the APD? APD receiver SOA+PIN receiver 1270 nm M 10G/25G APD x 1270 nm M 10G/25G PIN x 20 nm wide 1260 nm λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux SOA diplexer 1280 nm demux λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux >1280 nm demux 1280 nm SOA diplexer 4

5 4x25G OLT receiver sensitivity: TDM co-existence, λ0-- esults BE 1E-3 and 25Gbit/s Wavelength 1270 nm, E 6dB APD, M = 12, F excess = 7.6dB APD, M = 12, F excess = 5.1dB NF SOA+Filter+PIN SOA 7dB NF SOA 8dB x-filter loss included 20nm optical filter bandwidth in SOA-based x SOA noise figure of 7dB and 8dB Si/Ge APD: M = 12 and F excess = 3.22 (5.1dB) InAlAs APD: M = 12 and F excess = 5.69 (7.6dB) No margins included for aging, etc NF = 7dB NF = 8dB SOA / PIN 20nm F = 7.6dB 1.3dB F = 5.1dB 0.1dB F = 7.6dB 0.4dB F = 5.1dB -0.8dB 5

6 4x25G OLT receiver sensitivity: TDM co-existence, λ0-- discussion The 100G OLT receiver, for TDM co-existence, can be designed such that the λ0 APD receiver filter loss is minimized to be the same as for single wavelength 25G OLT BOSA (one ): 25G OLT 100G OLT λ 0 Tx (O+) λ 0 M x (O-) 1270 nm M 10G/25G APD x λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux SOA diplexer 1280 nm demux In this case APD and SOA+PIN (with 20 nm ASE filter) receivers provide about the same performance for λ0 receiver sensitivity 6

7 4x25G OLT receiver sensitivity: λ3 How much receiver sensitivity benefit (measured at ) does the SOA demux PIN implementation bring relative to the APD? WDM co-existence case shown APD receivers SOA+PIN receivers 1270 nm 10G x 1270 nm 10G x λ 0 25G APD x λ 0 25G PIN x λ 1 25G APD x λ 2 25G APD x λ 3 25G APD x λ demux 2.5 db demux diplexer λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux 2.5 db SOA demux diplexer Bandpass = GHz 7

8 4x25G OLT receiver sensitivity: λ3-- esults BE 1E-3 and 25Gbit/s Wavelength 1270 nm, E 6dB APD, M = 12, F excess = 7.6dB APD, M = 12, F excess = 5.1dB SOA, NF SOA 8dB SOA, NF SOA 7dB x-filter loss included 400GHz optical filter bandwidth in SOA-based x SOA noise figure of 7dB and 8dB Si/Ge APD: M = 12 and F excess = 3.22 (5.1dB) InAlAs APD: M = 12 and F excess = 5.69 (7.6dB) No margins included for aging, etc SOA / PIN 400GHz NF = 7dB NF = 8dB F = 7.6dB 4.9dB F = 5.1dB 3.7dB F = 7.6dB 4.1dB F = 5.1dB 2.9dB 8

9 4x25G OLT receiver sensitivity: λ3-- discussion Vs. an APD receiver, the SOA demux PIN receiver with GHz ASE filter provides appreciable sensitivity benefit, between ~ 3-5 db. Therefore this confirms expectations that SOA preamps will be used in 100G OLTs. The same SOA demux PIN performance also applies to λ 1 - λ 3 for the TDM co-existence case: 1270 nm M 10G/25G APD x TDM co-existence WDM co-existence 1270 nm 10G x λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux 2.5 db SOA diplexer 1280 nm demux λ 0 25G PIN x λ 1 25G PIN x λ 2 25G PIN x λ 3 25G PIN x λ demux 2.5 db SOA demux diplexer 9

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11 Backup 11

12 Equations - BE i1 r i1 r BE erfc erfc Gaussian probability density function at the decision circuit voltage at the sampling times for bit 1 and bit 0 assumed r is inverse extinction ratio: i 0 / i 1 (i x expectation of photocurrent for a received one x = 1 and zero x = 0) σ x with x = 1 and 0 is standard deviation of zero and one Decision threshold is set to (i 1 + i 0 ) / 2 Equal probabilities of logical 0 and

13 Equations - APD 2i i i M S FL FL P (1 r) Signal photocurrent in 1 in in P in is average optical input power, M 0 APD multiplication factor, S responsivity, FL 1, FL 2 loss of x-filters, i in resulting average photocurrent Standard deviation 2 2 x shot,x Shot noise 2 esm F ( FL FL ) P B 2 ei B, P 2 P / (1 r), P 2 P / (1 (1/ r)) 2 shot,x 0 excess 1 2 x,in e dark e 1, in in 0, in in e elementary charge, F excess excess noise factor of APD, P x,in optical power of the zero and one level, B e electrical bandwidth of the receiver, I dark dark current TIA Thermal noise and electrical amplifier noise TIA 4 e ktb F TIA k Boltzmann constant, T chip temperature, F TIA noise factor of electrical amplifier, load resistor of TIA 13

14 Equations SOA+Filter+PIN 2iin i (1 r) i S FL P FL G Signal photocurrent 14 1 in 1 in 2 SOA Standard deviation Shot noise: x S-ASE, x ASE-ASE shot,x TIA G SOA is SOA gain 2 es( FL G )( FL P ) B 4 es( FL ( G 1))n w B B 2eI B shot,x 2 SOA 1 x,in e 2 SOA sp o o e dark e n sp : Inversion factor, w o minimum noise spectral power density in one polarization added by OA, B o optical filter bandwidth Signal-ASE beat noise: 4 S( FL G )( FL P )S( FL ( G 1))n sp w o B ASE-ASE beat noise: S-ASE,x 2 SOA 1 x,in 2 SOA e B 4 S (( FL ( G 1)) ) w n (B ( ))B e ASE-ASE 2 SOA o sp o e