Consideration about wavelength allocation in O-band

IEEE P802.3ca -EPON Task Force meeting, Whistler Consideration about wavelength allocation in O-band Tomoyuki Funada May 24-25, 2016

Introduction 29dB channel insertion loss with 25Gbps/lane is challenging. We showed importance of efficient use of O-band to achieve low Transmitter and Dispersion Penalty (TDP) in previous meeting. This presentation adds background information for considering wavelength allocation. Required wavelength bandwidth for cooled and uncooled Transmitter. 25G ONU Bi-D structure and relative cost. channel insertion loss estimation. Wavelength allocation example in O-band. IEEE P802.3ca -EPON Task Force meeting, Whistler 2/11

Major questions Introduction - Discussion at previous meeting - Possibility of I-temp. (-40 to +85C) operation with 13nm band. Cost impact of ONU Bi-D One of our Task Force goal is to have economical 25G solution. Example shown at previous meeting 10G-EPON US NG-EPON US ONU Bi-D: use collimated light coupling NG-EPON DS (50G) 25G 10G US >5nm US 4λ >5nm 13nm band US/DS gap >20nm 25G US (uncooled) DS 4λ 25G DS US/DS gap >20nm 10G 1G US (reduced) 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 IEEE P802.3ca -EPON Task Force meeting, Whistler 3/11

Uncooled DML Required wavelength bandwidth - Uncooled devices - Wavelength distribution at constant case temperature: <±2nm Temperature dependency; 0.095nm/deg.C Require 16nm band for I-temp (-40 to 85deg.C). But we have to take into account that 25Gbps I-temp operation with high extinction ratio (ex. >6dB) is still challenging, and we need further study. Distribution of 10G DML on CWDM grids (>2000 samples from 15 wafers, Pout=Constant) Delta from band center [nm] Average: -7.2nm Sigma: 0.47 Delta from band center [nm] Average: -1.2nm Sigma: 0.47 Delta from band center [nm] Average: +5.2nm Sigma: 0.45 IEEE P802.3ca -EPON Task Force meeting, Whistler 4/11

Cooled EML Required wavelength bandwidth -Cooled devices- 4nm bandwidth is enough for cooled EML. 800GHz grid LAN-WDM (2nm bandwidth) Need loose tuning with TEC temperature or laser current, or loose λ screening Hz or 200GHz grid DWDM Need tight tuning with TEC temperature and laser current, plus λ screening Distribution of 10G-EPON EML (>8,000 samples from >10 wafers, Pout=Constant) Average: -0.9nm Sigma: 0.41 Delta from band center [nm] IEEE P802.3ca -EPON Task Force meeting, Whistler 5/11

Bi-D relative cost Bi-D structure and relative cost - Collimate and non-collimate - In the case of 10G, collimated light coupling is 1.4 times higher In the case of 25G, the difference will be smaller as Tx and Rx cost increase Benefits of collimated light coupling Narrower DS/US gap; 25nm (non-collimate: 40nm) Narrower Rx guard band; ±5nm (non-collimate: ±15nm) 800GHz grid LAN-WDM filter is also doable Higher Tx output power; 0.5 to 1dB higher (increase of fiber coupling efficiency) US/DS WDM filter 1270nm 1577nm Tx Wavelength Rx Isolator Block Filter 10G Bi-D module (10G-EPON) (Narrow DS/US gap and Rx guard band) IEEE P802.3ca -EPON Task Force meeting, Whistler 6/11

Uncooled DML could be a candidate for 25G system? -Tx Power & TDP of current Tx devices - 29dB channel insertion loss, we need Tx with higher power and lower TDP. Adoptable Tx Power (min) spec. of current uncooled DML ONU Bi-D is 4 to 6dBm. Potential improvement; (1) Bi-D with higher coupling efficiency optical system (e.g. Collimate); 0.5 to 1dB (2) FEC with higher coding gain; >1dB Uncooled DML is on the border line, do we pursue opportunity or do we forget? 25G devices in O-band (estimation) Tx Power (min.) +8 +5 +2 Cooled SOA-EML Cooled EML Uncooled DML 25G target spec. (+4 to 5dB from 10GBASE-PR) (2) FEC improvement (1) Bi-D optical coupling improvement 10GBASE-PR Spec 1 2 3 TDP(max) IEEE P802.3ca -EPON Task Force meeting, Whistler 7/11

25G Rough estimation of channel insertion loss Use of uncooled DML may need FEC with higher coding gain than RS (255, 223), we need more study on APD receiver sensitivity with DML transmitter. SOA integrated EML + APD can achieve 29dB channel insertion loss 29dB channel insertion loss is doable with a help of SOA receiver. Parameter Optics Type 25G Notes (1) Tx output power min. [dbm] (2) Rx sensitivity max. at BER=10-3 [dbm] (3) Transmitter and Dispersion Penalty [db] Uncooled DML Cooled DML SOA-EML APD SOA+PINPD DML SOA-EML +6.5 (*) +7 to +7.5 (*) +7.5 to +8-23 (need study) -24-27 (**) 2.0 1.5 IEEE P802.3ca -EPON Task Force meeting, Whistler ER>6dB ER>6dB ER>8dB ER=6dB ER=8dB ER=8dB, 2nm bandwidth 1280-1310nm 1260-1360nm (4) 4λ WDM loss [db] NA 4 (***) Include Tx and Rx Channel insertion Loss [db] (1)-(2)-(3)-(4) (*) Higher coupling efficiency optical system (**) Estimated from BASE-ER4 specification, -21.4dBm (OMA) at BER=10-12 (***) Thin film filter type See Tanaka_3ca_1_0524.pdf for 25G DML in detail 8/11

Wavelength allocation in O-band, example 1 Allocation example 1: 25G US use uncooled Tx 25G; 16nm bandwidth for US Keep possibility of adopting economical uncooled Tx for 25G ONU Need collimated light coupling Bi-D for 25G ONU to filter DS ; 800GHz grid LAN-WDM Keep opportunity for 4λ integrated Optical Sub-Assembly (OSA) Realize high Rx sensitivity by using SOA pre-amplifier Enough margin for wavelength deviation caused by burst mode operation of Tx 10G-EPON US NG-EPON US NG-EPON DS (50G) 25G 10G US 6nm 16nm Band 1286-1302nm 25G US (uncooled) 16nm Band 6nm US 4λ 54nm 16nm Band DS 4λ 8nm 4nm Band 25 G DS 10G 1G US (reduced) 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 IEEE P802.3ca -EPON Task Force meeting, Whistler 1360 9/11

Wavelength allocation in O-band, example 2 Allocation example 2: 25G use cooled Tx 25G; 4nm bandwidth with proper guard band Higher cost than uncooled, but lower cost than 800GHz grid LAN-WDM Lower cost non-collimated light coupling Bi-D can be adoptable in this example ; 800GHz grid LAN-WDM 10G-EPON US NG-EPON US NG-EPON DS (50G) 25G 10G US 4nm Band 1288-1292nm 8nm 25 G US 7nm 16nm Band US 4λ 16nm Band DS 4λ 64nm 18nm 4nm Band 25 G DS 10G (narrow) 1G US (reduced) 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 IEEE P802.3ca -EPON Task Force meeting, Whistler 10/11

Summary 29dB channel insertion loss; Need high power and low TDP transmitter SOA integrated EML; Good candidate, as presented in previous meeting Uncooled DML; On the border line Tx output power can be improved by Bi-D light coupling structure Need more study on APD receiver sensitivity when DML transmitter is used Allocation in O-band and 25G (dedicated wavelength lanes) in O-band is doable Examples [Example 1] 25G uncooled Tx [Example 2] 25G cooled Tx Thank you IEEE P802.3ca -EPON Task Force meeting, Whistler 11/11