Glen,
You asked – “Can
we somehow translate the 60825 requirements into a maximum limit for launch
power at ONU?”
The answer is that to do this properly you
have to apply all of the rules found in IEC 60825-1 and 60825-2 and the maximum
power you get depends on wavelength. However, Table D.1 of IEC 60825-2
contains the limits for 11 um mode field diameter single mode fibre for the
following wavelengths:
1310 nm 15.6 mW (+12 dBm)
1420 nm 10 mW (+10 dBm)
1550 nm 10 mW (+10 dBm)
“is it reasonable
to anticipate that a customer sooner or later will decide to look directly into
the ONU connector?”
I think that the answer
to that is definitely “Yes”
“Is it reasonable that a customer will try to pry open a shutter
door that a connector may have.”
I think that this is much more difficult
to answer and may be affected by how difficult it is to do etc.
“Is the ONU’s
mode of operation when it shuts down its laser when it sees no incoming signal
a reasonable measure to classify higher-power optics as class 1?”
I think that the correct
terminology for equipment that operates at high power levels and automatically shuts
down in the event of loss of continuity of the link is that it is Hazard level
1.
The answer to whether an
ONU is Hazard level 1 because of a shutdown mechanism depends on things like
the time between the loss of continuity of the link and the power reduction (I think
that this must be < 1 second for unrestricted locations) and the reliability
of the shutdown mechanism (e.g. software based shutdown may not be reliable
enough).
This is a complex subject
– see IEC 60825-2 for details.
IEC 60825-2 also contains information specific
to PONs. For example clause D.4.6
Regards,
Nortel Networks UK Limited,
External +44 1279 402540 Fax +44
1279 405670 ESN 742 2540
Email: pja@nortel.com
From:
Glen Kramer [mailto:glen.kramer@teknovus.com]
Sent: 01 November 2006 20:51
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON] FW:
[8023-10GEPON] 10GEPON ad hoc on higher split ratio - Conference Call Minutes
> Class 4 lasers are of high power
… may have sufficient energy to ignite materials …
That’s what I need! Now we are talking business.
Seriously, our RAP stated that our project won’t
“result in any health, safety, security, or environmental guidance that
affects or applies to human health or safety”. For 1G EPON, clause
60 explicitly limits us to class I optics and it explicitly refers to IEC
60825:
60.8.2 Laser safety
1000BASE-PX10 and 1000BASE-PX20 optical transceivers shall
conform to Class 1 laser requirements as
defined in IEC 60825-1, under any condition of operation.
This includes single fault conditions whether
coupled into a fiber or out of an open bore. Conformance to
additional laser safety standards may be
required for operation within specific geographic regions.
I am not very clear how
to interpret the Class I rules below:
A class 1 laser
is safe for use under all reasonably-anticipated conditions of use; in other
words, it is not expected that the maximum permissible exposure (MPE) can be
exceeded. This class may include lasers of a higher class whose beams are
confined within a suitable enclosure so that access to laser radiation is
physically prevented.
What are all reasonably-anticipated conditions and
what is expected MPE? For
example, is it reasonable to anticipate that a customer sooner or later will
decide to look directly into the ONU connector? Is it reasonable that a
customer will try to pry open a shutter door that a connector may have.
Is the ONU’s mode
of operation when it shuts down its laser when it sees no incoming signal a
reasonable measure to classify higher-power optics as class 1? My point is that
this protection (a useful side-effect of MPCP, really) is done at a protocol
level, way above PMD.
Can we somehow translate
the 60825 requirements into a maximum limit for launch power at ONU?
Glen
Tom,
Good data. I am not sure why you were not able to post. I
am forwarding this to the reflector (phone and e-mail from you signature were
removed to curb spam).
Glen
Glen, I
tried posting to the listserv but I guess I’ve only got Lurking
permissions. I have some awareness of laser safety as our test products
use Lasers up to 20 mw or so:
As one
might expect Laser Safety is not a simple issue. Requirements are
generally concerned about optical power density (mw/cm^2). I would guess
that an EDFA output at +20 dB (100 mW) could fall under class IIIB.
Revised system
In 2002 the system of Laser Classes was
revised as part of a revision of the international laser safety standard, IEC 60825. The revision was based on the
greater knowledge of lasers that had accumulated since the original
classification system was devised, and was intended to permit certain types of
lasers to be recognized as having a lower hazard than was implied by their
placement in the original classification system. The revised system is expected
to be adopted for use in the
class I
A class 1 laser
is safe for use under all reasonably-anticipated conditions of use; in other
words, it is not expected that the maximum permissible exposure (MPE) can be
exceeded. This class may include lasers of a higher class whose beams are
confined within a suitable enclosure so that access to laser radiation is
physically prevented.
class IM
Class 1M lasers
produce large-diameter beams, or beams that are divergent. The MPE for a Class
1M laser cannot normally be exceeded unless focusing or imaging optics are used
to narrow down the beam. If the beam is refocused, the hazard of Class 1M
lasers may be increased and the product class may be changed.
class II
A class 2 laser
emits in the visible region. It is presumed that the human blink reflex will be
sufficient to prevent damaging exposure, although prolonged viewing may be
dangerous.
class IIM
A class IIM laser
emits in the visible region in the form of a large diameter or divergent beam.
It is presumed that the human blink reflex will be sufficient to prevent damaging
exposure, but if the beam is focused down, damaging levels of radiation may be
reached and may lead to a reclassification of the laser.
class IIIR
A class 3R laser
is a continuous wave laser which may produce up to five times the emission
limit for Class 1 or class 2 lasers. Although the MPE can be exceeded, the risk
of injury is low. The laser can produce no more than 5 mW in the visible
region.
class IIIB
A class 3B laser
produces light of an intensity such that the MPE for eye exposure may be
exceeded and direct viewing of the beam is potentially serious. Diffuse
radiation (i.e., that which is scattered from a diffusing surface) should not
be hazardous. CW emission from such lasers at wavelengths above 315 nm
must not exceed 0.5 watts.
class IV
Class 4 lasers
are of high power (typically more than 500 mW if cw, or 10 J/cm² if
pulsed). These are hazardous to view at all times, may cause devastating and
permanent eye damage, may have sufficient energy to ignite materials, and may
cause significant skin damage. Exposure of the eye or skin to both the direct
laser beam and to scattered beams, even those produced by reflection from
diffusing surfaces, must be avoided at all times. In addition, they may pose a
fire risk and may generate hazardous fumes.
(From The Physical and Theoretical
Tom Durston
Product Development
Manager
Greenlee /
Textron
From:
Glen Kramer [mailto:glen.kramer@TEKNOVUS.COM]
Sent: Wednesday, November 01, 2006
1:21 PM
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON]
10GEPON ad hoc on higher split ratio - Conference Call Minutes
David,
What about upstream
launch power? I am not sure, but I’d guess the safety rules would
be different for CO and for a household.
Are there any volunteers
to make a short overview presentation on the topic?
Glen
From:
David Piehler [mailto:dpiehler@ALPHION.COM]
Sent: Wednesday, November 01, 2006
6:55 AM
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON]
10GEPON ad hoc on higher split ratio - Conference Call Minutes
I don’t know the
exact safety issues involved, but I do know that carriers deploying the video
overlay do launch up to +20 dBm at 1550 nm into the OSP fiber. Also in
the CATV world, this type of launch power is not uncommon.
David Piehler
Alphion
mobile: +1 732 692 4581
From:
Glen Kramer [mailto:
Sent: Tuesday, October 31, 2006
11:49 AM
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON]
10GEPON ad hoc on higher split ratio - Conference Call Minutes
Mike,
This is a great point.
Could you provide some more info on class 1 safety? In general, what
regulations apply to CPE side and to CO side? It would be great to have a
presentation in November covering this topic. It definitely should be
part of the set of constraints that the high-split ad hoc considers.
Glen
From:
Sent: Tuesday, October 31, 2006
11:35 AM
To:
STDS-802-3-10GEPON@listserv.ieee.org
Subject: Re: [8023-10GEPON]
10GEPON ad hoc on higher split ratio - Conference Call Minutes
Dear
all,
One
question related to the higher split ratio that I haven't seen discussed is
related to laser eye safety. Is this a problem for
EPON? For other ethernet standards we've normally required class 1
eye safety. I think powers significantly higher than
this are being considered here.
Regards,
Director
Transceiver Engineering
Picolight Inc
CO 80027
Tel 303 530 3189 x7533.
mike.dudek@picolight.com
From:
Sent: Tuesday, October 31, 2006 1:06 AM
To: STDS-802-3-10GEPON@listserv.ieee.org
Subject: [8023-10GEPON] 10GEPON ad hoc on higher split ratio - Conference Call
Minutes
Dear
all,
below
please find the conference call minutes, taken down by Glen (thank You for the
job well done)
please
let me know if You find any irregularities in the minutes or if You have any
comments on those.
*******************************************************************************
Attendees:
Haim Ben-Amram
Russell Davey
Glen Kramer
Marek Hajduczenia
Frank Chang
Silvia Pato
David Piehler
Harold Kamisugi
Bin Yeong Yoon
Dong Soo Lee
Wael Diab
Task 1: estimation of
1x64 and 1x128 port splitter power loss values
---------------------------------------------------------------------
Discussed Marek's
presentation. Few questions about derivation of splitter loss. No objections.
Task 1 is considered completed.
Task 2: non-linear
effects in fiber channel
-------------------------------------------
Silvia gave brief
overview of the paper on non-liner effects in 10GEPON. SBS seems like major
impairment. Mentioned dithering technique for laser sources.
Questions that need
more research:
1) Can video-overlay
even be supported on 1x128 PON? What power budget will be required?
2) Can we use
high-power source for data wavelength and use video-overlay? Effects of Raman
crosstalk due to high-power source.
AR: Silvia will finish
sub-task 2.2 "estimate the maximum launch power into fiber which can be
achieved without introducing non-linear effects" by November 6th.
Task 3: TX/RX
technology
----------------------
Bin Yeong Yoon and
dong Soo Lee are in the process of compiling a survey of receivers,
transmitters, and amplifiers available on the market today.
AR: Bin Yeong Yoon is
to finish the first draft later this week. Then narrow down the viable
configurations based on input from task 2.
Task 4: power margins
in the EPON systems
-----------------------------------------
It seemed to be
difficult to get this data from carriers. It was decided that for now we will
reverse-calculate this data from insertion loss taken in 802.3ah. We later may
update it with more accurate numbers based on carriers' responses to a
wavelength/power survey.
AR: Marek is to
calculate allocation for penalties and outside plant aging and repair margins
later this week.
An additional
conference call may be scheduled to discuss final drafts of the presentations.
*******************************************************************************
Best
wishes
Marek
Hajduczenia (141238)
(PhD Student - COM RD1)
SIEMENS
Networks S.A. - IC
Rua Irmãos Siemens, 1
Ed. 1, Piso 1
Alfragide
2720-093 Amadora
Portugal
* Marek.Hajduczenia@siemens.com
http://marekhaj.easyisp.pl/index.php
(+351.21.416.7472 4+351.21.424.2082
