My thinking was that ...
Since we are talking about two new ribbon cables between boxes in a datacenter
using these VCSEL arrays, it doesn't really matter if the legacy cable
plant is pairs of OM2 or OM1; however, OM3 is indeed the dominant MM media
deployed in datacenters as of now.
Now if there is a requirement / SG objective for HS-Ethernet over a single
pair of legacy OM2/OM1, that changes things entirely... but I haven't heard
anyone considering / proposing this.
-----Original Message-----
From: Mike Bennett [mailto:mjbennett@xxxxxxx]
Sent: Thursday, September 28, 2006 4:58 PM
To: Roger Merel
Cc: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Regarding LW & SW VCSELs
Roger,
What you say regarding OM3 is true, however, I don't think OM3 is
dominant in the installed base. Perhaps that doesn't matter if it
is
approaching dominance by the time we finish, but I haven't seen any data
to suggest it will be. Does anyone have such data that they're willing
to share with the study group?
Mike
Roger Merel wrote:
> Wenbin raises an important point. Going with LW VCSELs on MMF
would likely be a disadvantage as the OM3 is only optimized for 850nm and
thus modal dispersion limited reach would be shorter for a LW VCSEL (to
~75m) vs a SW VCSEL (up to 300m or so).
>
>
> -----Original Message-----
> From: Wenbin Jiang [mailto:Wenbin.Jiang@xxxxxxxx]
> Sent: Thursday, September 28, 2006 3:26 PM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Frank,
>
> With the right volume, the cost difference between a LW VCSEL chip
and a directly modulated DFB laser chip is up for debate. However, an optical
isolator is normally needed for the DFB laser, but not for the LW VCSEL.
>
> In the 2nd case, 850nm VCSEL parallel link should match well with
the data center reaches of <100m. The advantage of going to LW VCSEL
is not obvious for this application if on MMF.
>
> Wenbin
>
>
> -----Original Message-----
> From: Frank Chang [mailto:ychang@xxxxxxxxxxx]
> Sent: Thursday, September 28, 2006 12:35 PM
> To: Wenbin Jiang; STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: RE: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Wenbin;
>
> I'm acually interested in both, but more for the 2nd case. What is
your opinion regarding LW VCSEL parallel link against a DFB based CWDM
link for datcenter reaches of <100m?
>
> Frank
>
> -----Original Message-----
> From: Wenbin Jiang [mailto:Wenbin.Jiang@xxxxxxxx]
> Sent: Wednesday, September 27, 2006 6:40 PM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation
> Considerations" by Roger Merel
>
> Frank,
>
> Do you mean to compare a LW VCSEL with a DFB for WDM or to compare
a LW VCSEL parallel link with a DFB based WDM link? In the 2nd case, it
is a matter of what the break-even distance is between the two links.
>
> Wenbin
>
> -----Original Message-----
> From: Frank Chang [mailto:ychang@xxxxxxxxxxx]
> Sent: Wednesday, September 27, 2006 5:41 PM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Jack et al.;
>
> The fibers.org article made a comment that "A VCSEL solution
is approximately five to 10 times cheaper than a WDM solution", I
guess it points to multiple 850nm VCSELs or array (if with monitoring??).
I amnot sure this statement still hold true for long wavelength (1310nm
or even 1550nm) VCSELs. Because of the disruptive nature in recipe or process,
the LW VCSEL may have cost structure totally different from its 850nm counterpart.
While LW VCSEL singlet could also be different from its array, just like
the article indicate its monitoring in an array still chalenging. My question
is can someone comment if LW VCSEL array can be potentially built cheaper
than a CWDM or WDM solution which is well available today?
>
> Thanks
> Frank
>
> -----Original Message-----
> From: Jack Jewell [mailto:Jack.Jewell@xxxxxxxxxxxxx]
> Sent: Wednesday, September 27, 2006 7:16 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation
> Considerations" by Roger Merel
>
> Marek,
> At OFC 2006, Picolight demonstrated a 1310nm VCSEL operating at 10.3Gbps
in an SFP+ module and transmitting over 20km of SMF (10GBASE-LR with an
extra 10km of fiber). This week at the European Conference on Optical Communications,
AMCC is demonstrating a 10.3Gbps link over 300m of 62.5um fiber (exceeding
the 10GBASE-LRM spec). It uses a similar Picolight SFP+ module with a 1310nm
VCSEL and a linear receiver. AMCC's EDC chip compensates for the limited
fiber modal bandwidth.
> http://www.lightreading.com/document.asp?doc_id=104440&WT.svl=wire1_6
> There have been other 10G demonstrations involving 1310nm and 1550nm
VCSELs by various companies.
> Regards,
> Jack
>
> -----Original Message-----
> From: Hajduczenia, Marek [mailto:marek.hajduczenia@xxxxxxxxxxx]
> Sent: Wednesday, September 27, 2006 12:51 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Dear Jack,
> I think that clarifies the situation to the point beyond any doubt.
> My questions were still though not answered - is there any valid demonstration
of long-wave VCSELs (1310nm, 1550nm) operating at data rate >= 3G that
You might be aware of ?
> Thanks for the answer
>
> Marek Hajduczenia (141238)
> (PhD Student - COM RD1)
> SIEMENS SA - IC
> Rua Irmãos Siemens, 1
> Ed. 1, Piso 1
> Alfragide
> 2720-093 Amadora
> Portugal
> * Marek.Hajduczenia@xxxxxxxxxxx
> *+351.21.416.7472 *+351.21.424.2082
>
> -----Original Message-----
> From: Jack Jewell [mailto:Jack.Jewell@xxxxxxxxxxxxx]
> Sent: terça-feira, 26 de Setembro de 2006 23:55
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Roger,
>
> My comments regarding the fibers.org article were not in any way meant
to slight the researchers whose work was reported, or their work, or to
disagree with any of Jack's (Cunningham's) quotes. I know Jack Cunningham
from way back and respect him greatly. The work they report only
adds to the technological feasibility of 12x10G VCSEL arrays. I apologize
for any possible misunderstanding.
>
> My discussion regarding the status of 12x3G and the technical feasibility
of 12x10G VCSEL arrays mostly comprises defensable facts, followed by a
reasonably-stated opinion. "Well on the way" indicates
that key capabilities have been demonstrated, in this case: 10G VCSEL speed,
significant commercial volume at 1x10G and 12x3G, reliability at 1x10G
and 12x3G, and operation at 12x10G. Of course challenges remain,
but not so fundamental as those already demonstrated. Yield and reliability
are sure to be concerns for any multi-laser approach, especially if very
high performance is required.
>
> You'll be hard-pressed to get any VCSEL vendors (or any other vendors!)
to divulge the technical details of their recipes. Instead I'll address
concerns about array reliability and yield in a general and nonproprietary
way. Unless VCSELs are explicitly mentioned, these properties apply
to ANY array of lasers, e.g. DFBs, FPs or VCSELs. WEAROUT RELIABILITY:
The wearout lifetime of a 12x array is usually NOT 12x shorter than that
of a singlet. It is only about 2x shorter in VCSEL experiments reported
by both Infineon and AOC. The fact that array wearout lifetime is
shorter at all (for any array) is only due to variation among the elements.
If all elements aged identically, the wearout lifetime for a 12x
array would be identical to that of a singlet. Better uniformity
results in better array lifetimes. NON-WEAROUT RELIABILITY: Worst-possible-case
early-failure rate is 12x higher for a 12x array compared to a singlet.
But again, the array penalty is often lessened by t!
he!
> nature of the root cause. For example, ESD is one culprit
for early, non-wearout, failure. If an ESD event kills a laser array
for a multi-laser product (parallel or WDM), the effect is the same as
if it kills a singlet in a serial product: it kills one module. In
this case there is no "array penalty," assuming the array is
equally susceptible to ESD as the singlet. VCSEL early-failure rates
are already extremely low. [Any numbers here would lead down a rathole
of definitions, conditions, exclusions, qualifications, etc.] YIELD:
Array yield behaves similarly to wearout reliability. The better
the uniformity, the closer the array yield approaches the singlet yield.
>
> Since nearly all concepts discussed at HSSG involve multiple-laser
sources of one kind or another, I hope the above is generally useful.
>
> Regards,
> Jack
>
> -----Original Message-----
> From: Roger Merel [mailto:roger@xxxxxxxxxxx]
> Sent: Tuesday, September 26, 2006 9:05 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> John (goes by "Jack") Cunningham is well versed in VCSELs.
The article is rather short and doesn't say very much. They are specifically
working on approaches for higher speed VCSELs. So I'm sure the "experimental"
is in the higher speeds.
>
> Jack Jewell below would suggest that single VCSEL products at 10G
+ arrays products at 2.5/3.125G, and a demonstration with IBM in 2003 are
together proof that 12x arrays at 10G not challenging... but by doing so
in such a way specifically raises the exact red flags we are all concerned
about... both yield and reliability for VCSELs scale inversely with direct
modulation speed (tied in part to current density)... such that unless
there is some new design and new material incorporated (rather than just
improved manufacturing process control), one would have to be suspect that
(10x or) 12x10G VCSEL arrays are and will continue to be "challenging".
>
> With that all said, I am NOT suggesting that a 10x or 12x VCSELs should
be precluded from a possible HS-Ethernet PMD. HS-Ethernet is going
to be challenging all-around. The VCSEL array solutions are a viable
avenue for some of the shorter distance applications.
>
> It would be beneficial if Jack or other VCSEL vendors would explain
what has changed in the technical basis of VCSELs to ameliorate the yield
and reliability concerns especially tied to modulation rate and current
density. This could provide the SG with comfort for moving from Demos
to Standards for (10x or) 12x 10G VCSELs.
>
> -Roger
>
> -----Original Message-----
> From: Jack Jewell [mailto:Jack.Jewell@xxxxxxxxxxxxx]
> Sent: Tuesday, September 26, 2006 7:19 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: Re: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> The tone of the fibers.org article misleadingly suggests that the
implementation of VCSEL arrays is "still at rather experimental stage."
Suffice it to say that there are well over 100,000 12-channel parallel
VCSEL-array link products operating in the field at present. Significant
volumes began several years ago and keep rising. Manufacturers and
users of these parallel optical interconnections are represented at 802.3
and the present HSSG. There is no need to discuss the technological
details of monitoring (the subject of the fibers.org article) here; it
is handled by various means. The parallel optical interconnect products
have undergone rigorous qualification by customers with the highest standards
of quality and reliability. VCSEL-array based parallel links are
real, and this email is surely traveling through some of them.
>
> The present links typically operate at a lane rate (channel rate)
of 2.7-3.3Gbps. Customer-driven initiatives are already underway to increase
the lane rate to 10Gbps. IBM (with Picolight) demonstrated a 12x10Gbps
link operating over 300m of MMF at OFC 2003. It used "SNAP-12"
modules, i.e. the same modules used today. Since then, 10Gbps VCSEL technology
has matured significantly, driven by 10GBASE-SR sales.
>
> Parallel optical links using VCSEL arrays, detector arrays, and MM
parallel fibers are well on the way to showing "technically feasible"
at speeds up to 120Gbps.
>
> Jack
>
> -----Original Message-----
> From: Hajduczenia, Marek [mailto:marek.hajduczenia@xxxxxxxxxxx]
> Sent: Tuesday, September 26, 2006 2:36 AM
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: [HSSG] Regarding presentation "Implementation Considerations"
by Roger Merel
>
> Dear all,
> If I recall it correctly, Roger expressed his concerns for the wavelength
selection plan on slide number 8 of his presentation and pointed out that
most likely the VCSEL arrays with 10 or more integrated sources can be
technologically challenging. I would only like to point out that perhaps
we should investigate his proposal to use integrated VCSEL arrays operating
at 10+ Gbit/s -> here is why: http://fibers.org/articles/news/8/8/10.
The arrays seems to be still at rather experimental stage though this is
not the first piece of evidence that such devices can be achieved and may
be a much cheaper solution than standard WDM systems ...
> Looking forward to receiving any feedback ...
> Best wishes
>
> Marek Hajduczenia
> (COM RD1)
> SIEMENS SA - IC
> Rua Irmãos Siemens, 1
> Ed. 1, Piso 1
> Alfragide
> 2720-093 Amadora
> Portugal
> * Marek.Hajduczenia@xxxxxxxxxxx
> *+351.21.416.7472 *+351.21.424.2082
>
> -----Original Message-----
> From: Andy Moorwood [mailto:amoorwood@xxxxxxxxxxxxxxxxxxx]
> Sent: segunda-feira, 25 de Setembro de 2006 18:36
> To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
> Subject: [HSSG] Reach Ad Hoc, call for participation and conference
call announce ment
>
> Dear HSSG Members,
> thank you to those who have already replied with their intent to join
this activity, let me echo John's request for participation. I want
to schedule a conference call for Thursday October 5th at 11 am to 12:30
Pacific with the following objectives:
> 1. Identify what media and reach information is already available
to the group for the nominated applications: "HPCC, Data Center, Metro,
others"
> 2. Identify what media reach questions are of particular interest
to the group. For example, the 10 gigabit LR specification has a
link budget capable of supporting a reach of 10km in many installations.
Are end users actually using this budget? considerably less ? or they could
use more ?
> 3. Define a schedule for future conference calls To facilitate data
sharing/viewing at the meeting we need to use some kind of collaborative
environment in addition to voice conferencing. Extreme uses "Conference
Place" by Intercall and I will host this kick off meeting (If other
members care to donate resources for future meetings this would be appreciated).
Live data sharing does however impose some restrictions in that a
member needs to be invited to the meeting place.
> Consequently I need a minimum of 24 hours notice prior to the meeting
if a member intends to participate.
> If a member wants to present at the meeting I need a minimum
of 48 hours notice and the slides (PDF or PPT) format Any requests
not meeting these timelines will be supported on a best efforts basis.
If it is possible to support audio only participation on a "drop
in basis" I will forward this to the reflector just prior to the meeting.
> Thanks for your support !
> Andy
>
--
Michael J. Bennett
Sr. Network Engineer
LBLnet Services Group
Lawrence Berkeley Laboratory
Tel. 510.486.7913