#include <ocsReduOptAmplifier.hh>

Public Member Functions
	ReduOptAmplifier (string InFileName, ReduOptSignal *oReduOptSignalTmp)
	Constructor.
	~ReduOptAmplifier ()
	Destructor, calls void ReleaseMemory(void).
void	SetFixedOutputPowerFromCurrentOptSignal (void)
	Used to initialize OutputPowerLinear.
void	SetFixedTotalOutputPowerFromCurrentOptSignal (void)
void	AmplifyOptSignal (void)
	Amplifies the reduced optical signal and adds PDG.
void	SetTypeAmplifier (typeAmplifier TypeAmplifier2)
typeAmplifier	GetTypeAmplifier (void)
void	SetTypeAmplifierNoise (typeAmplifierNoise TypeAmplifierNoise2)
void	SetPolDepGain (double PolDepGainOptAmplifier2)
void	SetGain (double dBGain2)
double	SteadyStateSaturatedGain (double InputPower)
void	SetGainCompressionSaturatedAmplifier (double GainTarget_dB, double GainCompression_dB, double OutputPowerTarget)
void	SyncNumChannels (void)
	Sets NumChannels = oReduOptSignal::NumChannels.
string	WriteTypeAmplifier (void)
string	WriteTypeAmplifierNoise (void)
void	WriteSteadyStateGainVersusPower (string OutFileName, double InputPowerMaxLinear, int NumPowerSteps)
	NOT USED by reduced model.
void	WriteSteadyInputPowerVersusOutputPower (string OutFileName, double InputPowerMaxLinear, int NumPowerSteps)
double	GetSaturatingPowerLinear (void)
	NOT USED by reduced model.
double	GetPolDepGain (void)
double	GetOutputPowerLinear (void)
double	GetLinearGainOptAmplif (void)
Private Member Functions
void	AllocateNoiseAmplitudeChannels (void)
void	ReleaseMemory (void)
	Releases memory allocated by void AllocateNoiseAmplitudeChannels(void).
void	AddPolDepGainEffect (void)
	Adds the PDG. Called by void AmplifyOptSignal(void).
double	GetGainFixedOutputPower (double InputPower)
	This method computes the linear gain of the amplifier.
Private Attributes
ReduOptSignal *	oReduOptSignal
	Pointer to the reduced optical signal object that is being amplified.
ReduPolDepAttenuator *	oReduPolDepAttenuator
double	StokesSignalTmp [4]
double	StokesNoiseTmp [4]
double	CenterFreq
double	ChannSpacing
int	NumChannels
double	dBGain
double	OutputPowerLinear
double	PolDepGainOptAmplifier
	The polarization dependend gain in dB, same as x_PDG in [WM 2001] p 489.
double	LinearGainOptAmplif
	The linear gain of the amplifier.
double	NoiseFigOptAmplifier
double	LinearNoiseFigOptAmplif
double	SpontaneousEmissionFactor
double	AmpLength
	NOT USED by reduced model.
int	NumZSteps
	NOT USED by reduced model.
double	SaturatingPower
	NOT USED by reduced model.
double	SaturatingPowerLinear
	NOT USED by reduced model.
double	SaturatingPowerdBm
	NOT USED by reduced model.
double	UnsaturatedGaindB
	NOT USED by reduced model.
double	UnsaturatedGainLinear
	NOT USED by reduced model.
double	UnsaturatedDifferentialGainLinear
	NOT USED by reduced model.
double *	NormalizedNoiseAmplitude
typeAmplifier	TypeAmplifier
	The type of amplifier.
typeAmplifierNoise	TypeAmplifierNoise
	The type of amplifier noise.
int	DebugLevel

Detailed Description

The reduced optical amplifier.
The model includes a simple model for gain saturated amplifiers as well as polarization dependent gain (PDG).

For a simple application you just need to call the constructor ReduOptAmplifier( string InFileName,ReduOptSignal *oReduOptSignalTmp) and the method void AmplifyOptSignal(void)

Constructor & Destructor Documentation

ReduOptAmplifier::ReduOptAmplifier	(	string	InFileName,
		ReduOptSignal *	oReduOptSignalTmp
	)

Constructor.

Parameters:

	string	InFileName: The name of the input parameter file
	ReduOptSignal	*oReduOptSignalTmp: Pointer to the reduced optical signal object that is to be amplified.

The constructor does the following:

Initializes class parameters that it gets from the ReduOptSignal object
Reads input parameters from file and initializes internal class parameters.
Initializes a ReduPolDepAttenuator object that is used internally to do the PDG.
Calls void AllocateNoiseAmplitudeChannels(void)

The parameters that need to be set in the input parameter file are as follows.

(Note that in some of the example input files we also include many other parameters. These are for our full time and frequency domain amplifier and are NOT required by the reduced amplifier. Consequently this constructor could be cleaned up quite a bit...)

TypeAmplifier: Should be set to 6; See ReduOptAmplifier::TypeAmplifier
TypeAmplifierNoise: Should be set to 4; See ReduOptAmplifier::TypeAmplifierNoise
NoiseFigOptAmplifier: The noise figure of the amplifier in dB
SpontEmissionFactor: The spontaneous emission factor for the noise, n_sp, on a linear scale.
PolDepGainOptAmplifier: The PDG in dB.

We only need to set one of NoiseFigOptAmplifier and SpontEmissionFactor since SpontaneousEmissionFactor = LinearNoiseFigOptAmplif/2.0 where LinearNoiseFigOptAmplif = dB2Linear(NoiseFigOptAmplifier)

The code knows which of these two parameters to use provided that the user sets the other one to zero in the input file.

So exactly one of NoiseFigOptAmplifier and SpontEmissionFactor must be zero in the input file.

References AllocateNoiseAmplitudeChannels(), AmpLength, CenterFreq, ChannSpacing, dB2Linear(), dBGain, dBm2Linear(), DebugLevel, ReduOptSignal::GetCenterFreq(), ReduOptSignal::GetChannSpacing(), ReduOptSignal::GetNumChannels(), LinearGainOptAmplif, LinearNoiseFigOptAmplif, log(), LogFile, LogFileSeparator(), LOWER_AND_UPPER, LOWER_ONLY, MANDATORY, NO_BOUNDS, NOISE_ON_SEMI_ANALYTICAL, NoiseFigOptAmplifier, NumChannels, NumZSteps, OPTIONAL_NO_WARNING, OPTIONAL_WARNING, oReduOptSignal, oReduPolDepAttenuator, OutputPowerLinear, PolDepGainOptAmplifier, ReadDouble(), ReadInt(), SaturatingPowerdBm, SaturatingPowerLinear, ReduPolDepAttenuator::SetPolDepAttenuation(), SpontaneousEmissionFactor, TypeAmplifier, TypeAmplifierNoise, UnsaturatedDifferentialGainLinear, UnsaturatedGaindB, UnsaturatedGainLinear, VECTOR_FIXED_OUTPUT_POWER, VECTOR_FIXED_TOTAL_OUTPUT_POWER, WriteTypeAmplifier(), and WriteTypeAmplifierNoise().

ReduOptAmplifier::~ReduOptAmplifier ( )

Destructor, calls void ReleaseMemory(void).

References ReleaseMemory().

Member Function Documentation

void ReduOptAmplifier::AddPolDepGainEffect ( void ) [private]

Adds the PDG. Called by void AmplifyOptSignal(void).

The PDG is implemented somewhat differently from the formulae given on page 489 of [WM 2001] but the final result will be identical.

In this method the idea is that PDG can be modeled by a negative-loss (i.e. gain!) PDL element, provided that the signal is rotated so that the high loss axis of the (negative loss) PDL element is lined up with the high gain direction for the PDG. The high gain direction for the PDG is the direction that is orthogonal to the direction determined by the total Stokes parameters.

The amount of gain in the high gain direction is given by
PolDepGainOptAmplifier*GetDegreeOfPolarization(StokesTotal) in dB.

References GetDegreeOfPolarization(), NumChannels, oReduOptSignal, oReduPolDepAttenuator, ReduPolDepAttenuator::PolDepAttenuate(), PolDepGainOptAmplifier, RotatesAboutY(), RotatesAboutZ(), ReduPolDepAttenuator::SetPolDepAttenuationX(), ReduOptSignal::StokesNoise, ReduOptSignal::StokesSignal, and TransRzRyV3to_Xhat().

Referenced by AmplifyOptSignal().

void ReduOptAmplifier::AllocateNoiseAmplitudeChannels ( void ) [private]

Allocates memory for double * ReduOptAmplifier::NormalizedNoiseAmplitude and initializes its values.

References ReduOptSignal::GetFrequency(), hPlanck, NormalizedNoiseAmplitude, NumChannels, oReduOptSignal, and SpontaneousEmissionFactor.

Referenced by ReduOptAmplifier(), and SyncNumChannels().

void ReduOptAmplifier::AmplifyOptSignal ( void )

Amplifies the reduced optical signal and adds PDG.

In the reduced model we use ReduOptAmplifier::TypeAmplifier = 6 = VECTOR_FIXED_TOTAL_OUTPUT_POWER

So you should ignore most the the options in the switch statement in this method.

The algorithm is as follows:

Compute LinearGainOptAmplifier = GetGainFixedOutputPower(oReduOptSignal->GetTotalPower())
The idea here is to chose the gain that will ensure that the total output power is given by the pre-specified value OutputPowerLinear
Amplify with gain given by LinearGainOptAmplifier. The amplification involves multiplying the Stokes parameters of the signal and noise in each channel as well as the oReduOptSignal->StokesExtraUnpolChannNoise by LinearGainOptAmplifier.
Add the noise in the oReduOptSignal->StokesExtraUnpolChannNoise where the noise figure is computed using the frequency of the central channel, which is assumed have index NumChannels/2 which it will if you use set the flag EvenlySpacedChannels = 1 in the reduced optical signal input parameter file.
Add the noise to the Noise Power in each of the channels.
Now that we have added noise the total power will be higher than the value we wnted it to be. So we decrease the power of the signal in each channel to end up with the required total output power. Note that we don't change the power of the noise in this step.
The consequence of the last step is that after many amplifications the noise power grows and the signal power drops. This is what happens in realistic gain saturated amplifiers.

See also:: void SetFixedOutputPowerFromCurrentOptSignal(void),
double GetGainFixedOutputPower(double InputPower),
double OutputPowerLinear,
void AddPolDepGainEffect(void)

References AddPolDepGainEffect(), ChannSpacing, dB2Linear(), dBGain, DebugLevel, GetGainFixedOutputPower(), ReduOptSignal::GetSignalPower(), ReduOptSignal::GetTotalPower(), Linear2dBm(), LinearGainOptAmplif, LogFile, LogFileSeparator(), NO_AMPLIFICATION, NOISE_ON_SEMI_ANALYTICAL, NormalizedNoiseAmplitude, NumChannels, oReduOptSignal, PolDepGainOptAmplifier, SCALAR_SATURATED, SCALAR_SIMPLE, SteadyStateSaturatedGain(), ReduOptSignal::StokesNoise, ReduOptSignal::StokesSignal, TypeAmplifier, TypeAmplifierNoise, VECTOR_FIXED_OUTPUT_POWER, VECTOR_FIXED_TOTAL_OUTPUT_POWER, VECTOR_SATURATED, and VECTOR_SIMPLE.

Referenced by OptAmplifier::AmplifyOptSignal().

double ReduOptAmplifier::GetGainFixedOutputPower ( double InputPower ) [private]

This method computes the linear gain of the amplifier.

The method returns the linear gain required to change the total power from an input value given by the parameter InputPower to the required TotalOutputPower = NumChannels*OutputPowerLinear. Note that the gain may actually be a loss in some circumstances.

See also:: OutputPowerLinear

NewNormalizedNoiseAmplitudePerChannel /= oReduOptSignal->GetNumChannels();

References ChannSpacing, LinearGainOptAmplif, NormalizedNoiseAmplitude, NumChannels, and OutputPowerLinear.

Referenced by AmplifyOptSignal().

double ReduOptAmplifier::GetLinearGainOptAmplif ( void ) [inline]

References LinearGainOptAmplif.

double ReduOptAmplifier::GetOutputPowerLinear ( void ) [inline]

References OutputPowerLinear.

double ReduOptAmplifier::GetPolDepGain ( void ) [inline]

References PolDepGainOptAmplifier.

double ReduOptAmplifier::GetSaturatingPowerLinear ( void ) [inline]

NOT USED by reduced model.

References SaturatingPowerLinear.

typeAmplifier ReduOptAmplifier::GetTypeAmplifier ( void ) [inline]

References TypeAmplifier.

void ReduOptAmplifier::ReleaseMemory ( void ) [private]

Releases memory allocated by void AllocateNoiseAmplitudeChannels(void).

References NormalizedNoiseAmplitude, and oReduPolDepAttenuator.

Referenced by SyncNumChannels(), and ~ReduOptAmplifier().

void ReduOptAmplifier::SetFixedOutputPowerFromCurrentOptSignal ( void )

Used to initialize OutputPowerLinear.

Our simple amplifier gain saturation model keeps the total power in the optical signal constant. To determine the constant output power level per channel the user should call this method in an application once just after the (noiseless) signal has been generated. It sets OutputPowerLinear to be the average power per channel on a linear scale of the current signal.

See also:: OutputPowerLinear,
void AmplifyOptSignal(void)

References ReduOptSignal::GetTotalPower(), oReduOptSignal, and OutputPowerLinear.

Referenced by SetFixedTotalOutputPowerFromCurrentOptSignal().

void ReduOptAmplifier::SetFixedTotalOutputPowerFromCurrentOptSignal ( void ) [inline]

References SetFixedOutputPowerFromCurrentOptSignal().

void ReduOptAmplifier::SetGain ( double dBGain2 )

References dB2Linear(), dBGain, DebugLevel, LinearGainOptAmplif, and LogFile.

void ReduOptAmplifier::SetGainCompressionSaturatedAmplifier	(	double	GainTarget_dB,
		double	GainCompression_dB,
		double	OutputPowerTarget
	)

References AmpLength, dB2Linear(), log(), SaturatingPowerLinear, SetTypeAmplifier(), UnsaturatedDifferentialGainLinear, UnsaturatedGainLinear, and VECTOR_SATURATED.

void ReduOptAmplifier::SetPolDepGain ( double PolDepGainOptAmplifier2 ) [inline]

References PolDepGainOptAmplifier.

void ReduOptAmplifier::SetTypeAmplifier ( typeAmplifier TypeAmplifier2 )

References DebugLevel, LogFile, TypeAmplifier, and WriteTypeAmplifier().

Referenced by SetGainCompressionSaturatedAmplifier().

void ReduOptAmplifier::SetTypeAmplifierNoise ( typeAmplifierNoise TypeAmplifierNoise2 )

References DebugLevel, LogFile, TypeAmplifierNoise, and WriteTypeAmplifierNoise().

double ReduOptAmplifier::SteadyStateSaturatedGain ( double InputPower )

References AmpLength, NumZSteps, SaturatingPowerLinear, and UnsaturatedDifferentialGainLinear.

Referenced by AmplifyOptSignal(), WriteSteadyInputPowerVersusOutputPower(), and WriteSteadyStateGainVersusPower().

void ReduOptAmplifier::SyncNumChannels ( void )

Sets NumChannels = oReduOptSignal::NumChannels.

References AllocateNoiseAmplitudeChannels(), ReduOptSignal::GetNumChannels(), NumChannels, oReduOptSignal, oReduPolDepAttenuator, ReleaseMemory(), and ReduPolDepAttenuator::SyncNumChannels().

void ReduOptAmplifier::WriteSteadyInputPowerVersusOutputPower	(	string	OutFileName,
		double	InputPowerMaxLinear,
		int	NumPowerSteps
	)

References LogFile, LogFileSeparator(), and SteadyStateSaturatedGain().

void ReduOptAmplifier::WriteSteadyStateGainVersusPower	(	string	OutFileName,
		double	InputPowerMaxLinear,
		int	NumPowerSteps
	)

NOT USED by reduced model.

References LogFile, LogFileSeparator(), and SteadyStateSaturatedGain().

string ReduOptAmplifier::WriteTypeAmplifier ( void )

References NO_AMPLIFICATION, SCALAR_SATURATED, SCALAR_SIMPLE, TypeAmplifier, VECTOR_FIXED_OUTPUT_POWER, VECTOR_FIXED_TOTAL_OUTPUT_POWER, VECTOR_SATURATED, and VECTOR_SIMPLE.

Referenced by ReduOptAmplifier(), and SetTypeAmplifier().

string ReduOptAmplifier::WriteTypeAmplifierNoise ( void )

References NOISE_OFF, NOISE_ON_BIASED, NOISE_ON_CONST_POWER_RANDOM_PHASE, NOISE_ON_GAUSSIAN_WHITE, NOISE_ON_NO_RNG, NOISE_ON_SEMI_ANALYTICAL, and TypeAmplifierNoise.

Referenced by ReduOptAmplifier(), and SetTypeAmplifierNoise().

Member Data Documentation

double ReduOptAmplifier::AmpLength [private]

NOT USED by reduced model.

Referenced by ReduOptAmplifier(), SetGainCompressionSaturatedAmplifier(), and SteadyStateSaturatedGain().

double ReduOptAmplifier::CenterFreq [private]

Referenced by ReduOptAmplifier().

double ReduOptAmplifier::ChannSpacing [private]

Referenced by AmplifyOptSignal(), GetGainFixedOutputPower(), and ReduOptAmplifier().

double ReduOptAmplifier::dBGain [private]

Referenced by AmplifyOptSignal(), ReduOptAmplifier(), and SetGain().

int ReduOptAmplifier::DebugLevel [private]

Referenced by AmplifyOptSignal(), ReduOptAmplifier(), SetGain(), SetTypeAmplifier(), and SetTypeAmplifierNoise().

double ReduOptAmplifier::LinearGainOptAmplif [private]

The linear gain of the amplifier.

Referenced by AmplifyOptSignal(), GetGainFixedOutputPower(), GetLinearGainOptAmplif(), ReduOptAmplifier(), and SetGain().

double ReduOptAmplifier::LinearNoiseFigOptAmplif [private]

Referenced by ReduOptAmplifier().

double ReduOptAmplifier::NoiseFigOptAmplifier [private]

Referenced by ReduOptAmplifier().

double* ReduOptAmplifier::NormalizedNoiseAmplitude [private]

This double array stores the NormalizedNoiseAmplitude factor for each channel.

This factor tells us how much noise is added by the amplifier and depends on the frequency of the channel. Note that we are using an amplifier with flat gain. The frequency dependence of the amount of noise that is added is explained in both of Agrawal's books.

Referenced by AllocateNoiseAmplitudeChannels(), AmplifyOptSignal(), GetGainFixedOutputPower(), and ReleaseMemory().

int ReduOptAmplifier::NumChannels [private]

Referenced by AddPolDepGainEffect(), AllocateNoiseAmplitudeChannels(), AmplifyOptSignal(), GetGainFixedOutputPower(), ReduOptAmplifier(), and SyncNumChannels().

int ReduOptAmplifier::NumZSteps [private]

NOT USED by reduced model.

Referenced by ReduOptAmplifier(), and SteadyStateSaturatedGain().

ReduOptSignal* ReduOptAmplifier::oReduOptSignal [private]

Pointer to the reduced optical signal object that is being amplified.

Referenced by AddPolDepGainEffect(), AllocateNoiseAmplitudeChannels(), AmplifyOptSignal(), ReduOptAmplifier(), SetFixedOutputPowerFromCurrentOptSignal(), and SyncNumChannels().

ReduPolDepAttenuator* ReduOptAmplifier::oReduPolDepAttenuator [private]

A ReduPolDepAttenuator object that is used internally to do the PDG

Referenced by AddPolDepGainEffect(), ReduOptAmplifier(), ReleaseMemory(), and SyncNumChannels().

double ReduOptAmplifier::OutputPowerLinear [private]

The output power per channel we want in the case of a noiseless amplifier.

CAUTION:
With ReduOptAmplifier::TypeAmplifier = VECTOR_FIXED_TOTAL_OUTPUT_POWER and when noise is added by the amplifier we keep the total power TotalPower = NumChannels*OutputPowerLinear constant.