Product Overview

The LT-25-M is a 25 GHz bandwidth lightwave transmitter module designed for RF over fiber, antenna remoting and broadband RF transmission applications using single mode optical fiber. This module uses a low noise, narrow linewidth, 1550nm distributed feedback (DFB) laser diode as Continuous Wave (CW) light source. A broadband Lithium Niobate (LiNbO3) optical modulator is employed to provide the linear modulation capability that has a modulation bandwidth of up to 30 GHz. This externally modulated transmitter design provides a high spur-free dynamic range and high input intercept point performances. The LT-25-M can also be used for digital transmission when driven by a wideband modulator driver.

Applications

• Optical Communication to 30 Gb/s
• Wideband RF Transmission over Fiber
• RF/IF Signal Distribution
• Antenna Remoting
• Optical Delay Lines
• Satellite Communication

Features

• Useful Bandwidth up to 30 GHz
• Highly Linear for Analog Transmission
• High Spur-Free Dynamic Range
• Low RIN, Narrow Linewidth DFB Laser
• Broadband LiNbO₃ Optional Modulator
• Status Monitoring: RS-232 (option)
• RS-232 interface for status monitoring

Feature Name	Description
General Specifications
Operating Wavelength	1550 nm ± 10 nm, ITU wavelength available
Optical Output Level	+4 dBm to +8 dBm
Optical Return Loss	50 dB min.
Linewidth (FWHM)	1 MHz max.
DFB Side Mode Suppression Ratio	50 dB typ.
Relative Intensity Noise (RIN)	-145 dB/Hz max.
Impedance	50 Ω
Frequency Response Flatness	±0.5 dB in any 1 GHz bandwidth
VSWR	2.0 : 1 max.
Input Damage Level	26 dBm max.
Analog Specification
Useful Bandwidth	0.01 to 30 GHz
1 dB comp. Level	+25 dBm typ.
Input IP3	26 dBm @ 10 GHz
Spurious Free Dynamic Range	105 dB/Hz typ.
2nd Harmonics Distortion	-70 dBc typ.
RF Link Gain @ 2 GHz**	-24 dB
RF Link Gain @ 20 GHz**	-28 dB
RF Link Gain @ 25 GHz**	-31 dB
IM3 Distortion	< -90 dBc max.
Digital Applications
Modulation Bandwidth	Up to 30 Gb/s
Data Format	NR, RZ
Drive Voltage Requirement	7.5 V p-p
Mechanical Specifications
Operating Temperature	-40° C to +70° C
Storage Temperature	-55° C to +85° C
Power Supply Requirements	+12 V DC, 2 A max.
Optical Connector	SC/APC, FC/APC Optional
RF Input Connector	K-Connector Female, 50 Ω
DC Connector	DB-15
Local Alarm	LED: Optional Input Power
Remote Alarms	RS-232 Interface (Optional)
Dimensions	208 mm x 108 mm x 30 mm
Accessories Included	110 V - 240 V AC Adaptor and RS-232 Cable
Housing	Precision Machined Aluminum, Anodized