1. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Examples of nanosecond pulses obtained by direct amplitude modulation of a ∼ 1030-nm-wavelength distributed feedback (DFB) diode laser. Inset: Detail of the ∼ 50-ps-long gain switch spike occurring at the leading edge of the pulses. All temporal profiles were recorded with an InGaAs photodector connected to a broadband real-time digital scope, yielding instrument temporal resolution ∼ 12 ps. (b) Spectra emitted by the amplitude modulated DFB diode laser [driven to generate ∼ 3-ns pulses at pulse repetition frequency (PRF)=100 kHz] for different diode temperatures, recorded with an optical spectral analyzer (0.01-nm resolution). At all temperatures, only two features, corresponding to longitudinal modes separated by ∼ 135 GHz in frequency and ∼ 27 dB in amplitude, are resolved. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

2. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic diagram and pulse sequence of composite seeder source consisting of single-frequency DFB or distributed-Bragg- reflector (DBR) laser seeding an semiconductor optical amplifier (SOA) used as a time-gated amplifier (see text for details). (b) Temporal profiles of typical nanosecond pulses emitted by the composite seeder, recorded with the same equipment described in the caption of Fig. 1. (c) Black trace: Output spectrum of a ∼ 3-ns-long pulse emitted by the SOA seeded by a DBR diode laser; red trace: Spectrum of DBR diode laser leakage through the SOA when the SOA is turned off. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

3. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic diagram of all-fiber master oscillator/power amplifier (MOPA) consisting of extended-cavity Fabry-Perot (ECFP) diode laser seeder (MO), phase modulator (FM), fiber-coupled Faraday isolator and 0.5-nm pass band filter (F/I), bidirectional tap coupler (BTC), and two-stage amplifier, featuring two pieces of ∼ 2.5-m long 10/125-μm core/cladding diameter Yb-doped fiber, each forward-pumped by 975-nm wavelength diodes through a pump/signal combiner (YDF1 and 2). (b) Spectrum of the seed light observed through the forward port of the BTC and recorded with a scanning confocal Fabry-Perot spectrometer: gray=phase modulator off; red=phase modulator on. (c) Spectrum of light propagating backward from YDF2, detected through the backward port of the BTC when the FM is “off” (gray trace) and “on” (red trace). Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

4. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Swept-PRF pulse pattern produced by master oscillator (ECFP diode laser) driven by arbitrary waveform generator. (b) Time- domain profile of the fiber-amplified pulse pattern; the vertical scale is calibrated to show the instantaneous pulse power (see text for details). (c) Average power of the amplified pulse pattern versus power pumping the final fiber amplifier (40-μm core Yb-doped PCF); inset: near-field profile of output beam, recorded at maximum power. (d) Peak-normalized spectrum of the amplified pulse pattern, recorded at maximum power. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

5. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic diagram of MOPA architecture featuring a Yb-doped longitudinally tapered fiber (YD-LTF) as last-stage amplifier; PD: pulse driver, MO: ECFP diode laser, F/I: PM fiber-coupled band-pass filter and optical isolator, YDF: Yb-doped fiber preamplifier, PD: pump diode lasers, PSC: all-fiber pump/signal combiner, DM: long-pass dichroic filter, P: free-space pump beam. (b) Pulse average power and corresponding pulse energy emitted by the YD-LTF amplifier versus pump power; inset: near-field image of output beam recorded at maximum power. (c) Time-domain profile of output pulses. (d) Peak-normalized spectrum of YD-LTF amplifier output recorded at maximum power. (e) Higher-resolution (0.01 nm) detail of pulse spectrum. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

6. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Pulse average power/energy versus power emitted by the diode lasers pumping the final, rod-type PCF amplifier in the case of 5-ns width/20-kHz PRF input pulse format; inset: intra-pulse power versus time, recorded when the MOPA emits 2.8-mJ/56 W pulse energy/average power. (b) Broadband OSA-recorded spectrum at the same pulse power. (c) Corresponding high-resolution spectrum of output pulses recorded with a scanning Fabry-Perot spectrometer. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

7. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic diagram of fiber-based MOPA architecture designed for high-peak power generation. PD: Electronic pulse driver; MO: master oscillator (amplitude-modulated DBR diode laser); FM: PM fiber-coupled phase modulator; SOA: PM fiber-coupled SOA; F/I: PM fiber-coupled band-pass filter and optical isolator; YDF: Yb-doped, PM fiber preamplifiers (10-μm core); YDTF: Yb-doped, PM, longitudinally tapered fiber having 25/40-μm input/output core diameter; RT-YDPCF: rod-type, Yb-doped, 100-μm-core PM photonic crystal fiber. (b) Output pulse energy and corresponding average power (obtained as pulse energy × PRF) versus power emitted by the diode lasers pumping the final, rod-type PCF amplifier; upper inset: pulse temporal profile recorded at maximum pulse energy (2.2 mJ); lower inset: near-field image of the output beam at maximum pulse energy. (c) Peak-normalized spectrum of the MOPA output at maximum pulse energy; inset: higher-resolution detail of the pulse spectrum. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105

8. Date of download: 5/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Cross-sectional photographs of 40-μm diameter core, single-polarization, single-transverse-mode Yb-doped photonic crystal fiber; (b) cross-sectional photograph of ∼ 100-μm diameter core, polarization maintaining (PM), few-moded Yb-doped rod-type photonic crystal fiber; (c) core diameter versus position along the fiber in a Yb-doped, longitudinally tapered fiber (25/40-μm input/output core diameter); (d) and (e) fusion-spliced beam expanding endcaps. Figure Legend: From: Development of pulsed fiber lasers for long-range remote sensing Opt. Eng. 2014;53(3):036105. doi:10.1117/1.OE.53.3.036105