Spampinato, A; Stacey, C; Mulholland, S; Robertson, B; Klein, H A; Huang, G; Barwood, G P; Gill, P (2924) An ion trap design for a space-deployable strontium-ion optical clock. Proceedings of the Royal Society A, 480 (2284). 20230593

Trigatzis, M; Knapp, M; Mulholland, S; Hockley, G; Barwood, G P; Huang, G; Klein, H A; Gill, P (2024) Progress towards a transportable laser-cooled Yb+ microwave clock. In: 2024 European Frequency and Time Forum (EFTF), 25-27 June 2024, Neuchatel, Switzerland.

Cole, G D; Koller, S; Greve, C; Barwood, G P; Deutsch, C; Gaynor, P; Ghulinyan, M; Gill, P; Hendricks, R; Hill, I; Kundermann, S; le Goff, R; Lecomte, S; Meier, C; Pepponi, G; Schitt, S; Stenzel, C; Sutterlin, R; Voss, K; Zhukov, A (2024) Towards space-deployable laser stabilization systems based on vibration-insensitive cubic cavities with crystalline coatings. Optics Express, 32 (4). pp. 5380-5396.

Curtis, E A; Nicholls, L; Black, N C G; Barwood, G P (2023) Frequency modulation laser spectroscopy method for methane isotopologue ratio and total concentration measurements at 1661 nm. Journal of the Optical Society of America B, 40 (6). pp. 1542-1549.

Spampinato, A; Stacey, J; Mulholland, S; Robertson, B I; Klein, H G; Huang, G; Barwood, G P; Gill, P (2023) Progress towards development of a trapped strontium-ion space optical clock. Proceedings of the SPIE, 12335. 1233502

Hill, I R; Hendricks, R J; Donnellan, S; Gaynor, P; Allen, B; Barwood, G P; Gill, P (2021) Dual-axis cubic cavity for drift-compensated multi-wavelength laser stabilisation. Optics Express, 29 (22). pp. 36758-36768.

Sanjuan, Josep; Abich, Klaus; Gohlke, Martin; Resch, Andreas; Schuldt, Thilo; Wegehaupt, Timm; Barwood, G P; Gill, P; Braxmaier, Claus (2020) Long-term stable optical cavity for special relativity tests in space: erratum (Optics Express, (2019), Vol. 27, Issue 25, p36206 - 36220). Optics Express, 28 (6). p. 7917. ISSN 1094-4087

Mulholland, S.; Klein, H. A; Barwood, G P; Donnellan, S.; Gentle, D.; Huang, G.; Walsh, G.; Baird, P. E. G.; Gill, P. (2019) Laser-cooled ytterbium-ion microwave frequency standard. Applied Physics B, 125 (11). 198 ISSN 0946-2171

Curtis, E A; Bradley, T; Barwood, G P; Edwards, C S; Wheeler, N V; Phelan, R; Richardson, D J; Petrovich, M N; Gill, P (2018) Laser frequency stabilization and spectroscopy at 2051 nm using a compact CO2-filled Kagome hollow core fiber gas-cell system. Optics Express, 26 (22). pp. 28621-28633. ISSN 1094-4087

Mulholland, S; Donnellan, S; Barwood, G P; Gentle, D; Huang, Guilong; Klein, H A; Patel, P; Walsh, G; Baird, P.E.G.; Gill, P (2018) A Portable Microwave Clock Using Laser-Cooled Trapped 171Yb+Ions. In: 2018 IEEE International Frequency Control Symposium (IFCS), 21-24 May 2018, Olympic Valley, CA, USA.

Barwood, G P; Gill, P; Klein, H A; Hosaka, K; Huang, G; Lea, S N; Margolis, H S; Szymaniec, K; Walton, B R (2017) Trapped strontium ion optical clocks. Proceedings of the SPIE, 10567. 105672U

Curtis, E A; Barwood, G P; Huang, G; Edwards, C S; Gieseking, B; Brewer, P J (2017) Ultra-high-finesse NICE-OHMS spectroscopy at 1532 nm for calibrated online ammonia detection. J. Opt. Soc. Am. B, 34 (5). pp. 950-958.

Origlia, S*; Schiller, S*; Pramod, M S*; Smith, L*; Singh, Y*; He, W*; Viswam, S*; Swierad, D*; Hughes, J*; Bongs, K*; Sterr, U*; Lisdat, C*; Vogt, S*; Bize, S*; Lodewyck, J*; Le Targat, R*; Holleville, D*; Venon, B*; Gill, P; Barwood, G P; Hill, I R; Ovchinnikov, Y B; Kulosa, A*; Ertmer, W*; Rasel, E M*; Stuhler, J*; Kaenders, W* (2016) Development of a strontium optical lattice clock for the SOC mission on the ISS. Proc. SPIE - Int. Soc. Opt. Eng., 9900. 990003

Barwood, G P; Huang, G; King, S A; Klein, H A; Gill, P (2016) Trapped-ion 88Sr+ optical clock systematic uncertainties - AC Stark shift determination. J. Phys.: Conf. Ser., 723. 012024

Barwood, G P; Huang, G; Klein, H A; Gill, P (2015) Automatic minimisation of micromotion in a 88Sr+ optical clock. Meas. Sci. Technol., 26 (7). 075203

Bongs, K*; Singh, Y*; Smith, L*; He, W*; Kock, O*; Swierad, D*; Hughes, J*; Schiller, S*; Alighanbari, S*; Origlia, S*; Vogt, S*; Sterr, O*; Lisdat, C*; Le Targat, R*; Lodewyck, J*; Holleville, D*; Venon, B*; Bize, S*; Barwood, G P; Gill, P; Hill, I R*; Ovchinnikov, Y B; Poli, N*; Tino, G M*; Stuhler, J*; Kaenders, W* (2015) Development of a strontium optical lattice clock for the SOC mission on the ISS. Comptes Rendus Physique, 16 (5). pp. 553-564.

Barwood, G P; Huang, G; King, S A; Klein, H A; Gill, P (2015) Frequency noise processes in a strontium ion optical clock. J. Phys. B, At. Mol. Opt. Phys., 48 (3). 035401

Fitzau, O*; Herper, M*; Giesberts, M*; Nicklaus, K*; Barwood, G P; Williams, R A; Gill, P; Koegel, H*; Hoffman, H D* (2015) High stability single-frequency Yb fiber amplifier for next generation gravity missions. Proc. SPIE - Int. Soc. Opt. Eng., 9344. 93440B

Barwood, G P; Huang, G; Klein, H A; Johnson, L A M; King, S A; Margolis, H S; Szymaniec, K; Gill, P (2014) Agreement between two 88Sr+ optical clocks to 4 parts in 10^17. Phys. Rev. A, 89 (5). 050501

Schiller, S*; Gorlitz, A*; Abou-Jaoudeh, C*; Mura, G*; Franzen, T*; Nevsky, A*; Alighanbari, S*; Chen, Q*; Ernsting, I*; Poli, N*; Schioppo, M*; Tino, G M*; Sterr, U*; Vogt, S*; Falke, S*; Lisdat, C*; Gill, P; Barwood, G P; Ovchinnikov, Y B; Rasel, E*; Kulosa, A*; Bongs, K*; Singh, Y*; Calonico, D*; Levi, F*; Stuhler, J*; Kaenders, W*; Bize, S*; Holtzwarth, R* (2013) Development of compact lattice optical clocks toward future space clocks. In: Lasers & Electro-Optics. Europe & International Quantum Electronics Conference (CLEO EUROPE/IQEC 2013), 12-16 May 2013, Munich, Germany.

Schiller, S*; Gorlitz, A*; Nevsky, A*; Alighanbari, S*; Vasilyev, S*; Abou-Jaoudeh, C*; Mura, G*; Franzen, T*; Sterr, U*; Falke, S*; Lisdat, C*; Rasel, E*; Kulosa, A*; Bize, S*; Lodewyck, J*; Tino, G M*; Poli, N*; Schioppo, M*; Bongs, K*; Singh, Y*; Gill, P; Barwood, G P; Ovchinnikov, Y B; Stuhler, J*; Kaenders, W*; Braxmaier, C*; Holzwarth, R*; Donati, A*; Lecomte, S*; Calonico, D*; Levi, F* (2013) The space optical clocks project: development of high-performance transportable and breadboard optical clocks and advanced subsystems. In: 2012 European Frequency and Time Forum (EFTF 2012), 23-27 April 2012, Gothenburg, Sweden.

Nevsky, A*; Alighanbari, S*; Chen, Q F*; Ernstring, I*; Vasilyev, S*; Schiller, S*; Barwood, G P; Gill, P; Poli, N*; Tino, G M* (2013) Robust frequency stabilization of multiple spectroscopy lasers with large and tunable offset frequencies. Opt. Lett., 38 (22). pp. 4903-4906.

Barwood, G P; Gill, P; Huang, G; Klein, H A (2012) Automatic laser control for a 88Sr+ optical frequency standard. Meas. Sci. Technol., 23 (5). 055201

Barwood, G P; Gill, P; Huang, G; Klein, H A (2012) Characterization of a 88Sr+ optical frequency standard at 445 THz by two-trap comparison. In: 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012), 1-6 July 2012, Washington DC, USA.

Edwards, C S; Barwood, G P; Patel, P D; Gill, P; Benabid, F*; Wheeler, N V*; Tandoi, G*; Ironside, C N* (2012) Development and evaluation of compact acetylene frequency standards. In: 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012), 1-6 July 2012, Washington DC, USA.

Edwards, C S; Patel, P D; Barwood, G P; Gill, P (2009) Development of a compact 1.55 µm acetylene standard using a widely tunable DSDBR diode laser. In: 9th Optical Fibre Measurement Conference (OFMC) Digest, 16-18 September 2009, NPL, Teddington,UK.

Margolis, H S; Barwood, G P; Huang, G; Klein, H A; Lea, S N; Marra, G; Tsatourian, V; Walton, B R; Gill, P (2008) An optical clock based on a single trapped 88Sr+ ion. In: Proceedings of the 7th Symposium on Frequency Standards and Metrology., 5-11 October 2008, Pacific Grove, California, USA.

Barwood, G P; Gill, P; Huang, G; Klein, H A (2007) Observation of a sub-10-Hz linewidth 88Sr+ 2S1/2-2D5/2 clock transition at 674 nm. IEEE Trans. Instrum. Meas., 56 (2). pp. 226-229.

Lea, S N; Webster, S A; Barwood, G P (2007) Polarisabilities and blackbody shifts in Sr+ and Yb+. In: Proceedings of the 20th European Frequency and Time Forum, 27-30 March 2006, PTB, Germany.

Ma, L S*; Picard, S*; Zucco, M*; Chartier, J-M*; Robertsson, L*; Balling, P*; Krin, P*; Jin Qian*,; Zhongyou Liu*,; Chunying Shi*,; Alonso, M V*; Gan Xu*,; Siew Leng Tan*,; Nyholm, K*; Henningsen, J*; Hald, J*; Rowley, W R C; Barwood, G P; Windeler, R* (2006) Absolute frequency measurement of the R(12) 26-0 and R(106) 28-0 transitions in 127I2 at =543nm. IEEE Trans. Instrum. Meas., 55 (3). pp. 876-880.

Edwards, C S; Margolis, H S; Barwood, G P; Lea, S N; Gill, P; Rowley, W R C (2006) Development of a pair of 1.5 micron NICE ohms frequency standards. In: CPEM 2006 Conference on Precision Electromagnetic Measurements, 9-14 July 2006, Torino, Italy.

Barwood, G P; Gill, P; Klein, H A; Huang, G; Walton, B R (2006) An optical frequency standard based on a transition in a single trapped strontium ion. In: CPEM 2006 Conference on Precision Electromagnetic Measurements, 9-14 July 2006, Torino, Italy.

Barwood, G P; Gill, P; Klein, H A; Huang, G; Walton, B R (2006) An optical frequency standard based on a transition in a single trapped strontium ion. In: CPEM 2006 Conference on Precision Electromagnetic Measurements, 9-14 July 2006, Torino, Italy.

Barwood, G P; Huang, G; Klein, H A; Margolis, H S; Lea, S N; Szymaniec, K; Chalupczak, W; Gill, P (2006) An optical frequency standard based on a transition in a single trapped strontium ion. In: Optical Frequency Combs for Space International Workshop, 2-3 October 2006, NPL, UK.

Webster, S A; Blythe, P E; Hosaka, K; Barwood, G P; Gill, P (2004) Systematics shifts of the 467 nm electric octupole transition in 171 Yb+. NPL Report. CBTLM 31

Edwards, C S; Margolis, H S; Barwood, G P; Lea, S N; Gill, P; Huang, G; Rowley, W R C (2004) Absolute frequency measurement of a 1.5µm acetylene standard by use of a combined frequency chain and femtosecond comb. Opt. Lett., 29 (6). pp. 566-568.

Edwards, C S; Margolis, H S; Barwood, G P; Lea, S N; Gill, P; Huang, G; Rowley, W R C (2004) Absolute frequency measurements of 1.5 micron acetylene-stabilized lasers. In: Conference on Precision Electromagnetic Measurements (CPEM) 2004, 27 June - 2 July 2004, London, UK.

Margolis, H S; Huang, G; Lea, S N; Barwood, G P; Klein, H A; Gill, P (2004) Comparison of two femtosecond optical frequency combs at NPL. In: Conference on Precision Electromagnetic Measurements (CPEM) 2004, 27 June - 2 July 2004, London, UK.

Barwood, G P; Margolis, H S; Huang, G; Gill, P; Klein, H A (2004) Determination of the quadrupole frequency shift of the 2S1/2 2D5/2 transition in 88Sr+ at 674 nm. In: Conference on Precision Electromagnetic Measurements (CPEM) 2004, 27 June - 2 July 2007, London, UK.

Edwards, C S; Margolis, H S; Barwood, G P; Gill, P; Rowley, W R C (2004) Frequency measurements of 778nm rubidium two photon diode laser diodes. In: Conference on Precision Electromagnetic Measurements (CPEM) 2004, 27 June - 2 July 2004, London, UK.

Margolis, H S; Barwood, G P; Huang, G; Klein, H A; Lea, S N; Szymaniec, K; Gill, P (2004) Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion. Science, 306 (5700). pp. 1355-1358.

Gill, P; Barwood, G P (2003) Ion trapping and laser applications to length and time metrology. In: Handbook of Laser Technology and Applications. IOP, Bristol, UK, pp. 2485-2506.

Barwood, G P; Gill, P (2003) Laser stabilisation for precision measurements. In: Handbook of Laser Technology and Applications. IOP, Bristol, UK, pp. 1393-1414.

Margolis, H S; Huang, G; Barwood, G P; Lea, S N; Klein, H A; Rowley, W R C; Gill, P; Windeler, R S* (2003) Absolute frequency measurement of the 674 nm 88Sr+ clock transition using a femtosecond optical frequency comb. Phys. Rev. A, At. Mol. Opt. Phys., 67. 032501

Lea, S N; Rowley, W R C; Margolis, H S; Barwood, G P; Huang, G; Gill, P; Chartier, J.-M*; Windeler, R S* (2003) Absolute frequency measurements of 633 nm iodine-stabilised helium-neon lasers. Metrologia, 40. pp. 84-88.

Barwood, G P; Gao, K*; Gill, P; Huang, G; Klein, H A (2003) Observation of the hyperfine structure of the 2S1/2 - 2D5/2 674 nm optical clock transition in 87Sr+. Phys. Rev. A, At. Mol. Opt. Phys., 67. 013402

Margolis, H S; Barwood, G P; Blythe, P J; Gill, P; Hosaka, K; Huang, G; Klein, H A; Lea, S N; Webster, S A (2003) Trapped ion optical Frequency standards and metrology. In: Digest of LEOS Summer Topical Meeting on Photonic Time/Frequency Measurement and Control, 14-16 July 2003, Vancouver, Canada.

Gill, P; Barwood, G P; Klein, H A; Huang, G; Webster, S A; Blythe, P J; Hosaka, K; Lea, S N; Margolis, H S (2003) Trapped ion optical frequency standards. Meas. Sci. Technol., 14 (8). pp. 1174-1186.

Edwards, C S; Barwood, G P; Gill, P; Rowley, W R C (2002) Development of a 778 nm rubidium two-photon diode laser frequency standard. In: Proceedings of the 6th Symposium on Frequency Standards and Metrology, 9-14 September 2001, University of St Andrews, Fife, Scotland, UK.

Lea, S N; Margolis, H S; Huang, G; Barwood, G P; Klein, H A; Blythe, P J; Webster, S A; Rowley, W R C; Gill, P; Windeler, R S* (2002) Femtosecond comb measurements of optical frequency standards at NPL. In: IEEE-LEOS 2002 15th Annual Meeting of the IEEE Lasers and Electo-Optics Society., 10-14 November 2002, Glasgow, UK.

Lea, S N; Margolis, H S; Huang, G; Rowley, W R C; Henderson, D; Barwood, G P; Klein, H A; Webster, S A; Blythe, P; Gill, P (2002) Femtosecond optical frequency comb measurements of lasers stabilised to transitions in 88Sr+, 171Yb+ and I2 at NPL. In: Proceedings of the 6th Symposium on Frequency Standards and Metrology, 9-14 September 2001, University of St Andrews, Fife, Scotland, UK.

Webster, S A; Taylor, P; Roberts, M; Barwood, G P; Gill, P (2002) Kilohertz resolution spectroscopy of the 2D1/2-2F7/2 electric octupole transition in a single 171Yb+ ion. Phys. Rev. A, At. Mol. Opt. Phys., 65 (5). 052501

Webster, S A; Taylor, P; Roberts, M; Barwood, G P; Gill, P (2002) Kilohertz resolution spectroscopy of the 2S1/2-1F7/2 electric octupole transition in a single 171Yb+ ion. Phys. Rev. A, At. Mol. Opt. Phys., 65 (5). 052501

Barwood, G P; Gill, P; Huang, G; Klein, H A (2002) Stability and reproducibility of an optical frequency standard based upon the 2S1/2 - 2D5/2 transition in 88Sr+. In: Proceedings of the 6th Symposium on Frequency Standards and Metrology, 9-14 September 2001, University of St Andrews, Fife, Scotland, UK.

Webster, S A; Taylor, P; Roberts, M; Barwood, G P; Blythe, P; Gill, P (2002) A frequency standard using the 2S1/2 - 2F5/2 octupole transition in 171Yb+. In: Proceedings of the 6th Symposium on Frequency Standards and Metrology, 9-14 September 2001, University of St Andrews, Fife, Scotland, UK.

Edwards, C S; Barwood, G P; Gill, P; Bell, S A; Stevens, M; Schirmer, B*; Melling, A*; Venzke, H*; Weber, H*; Benyon, R*; Mackrodt, P*; Nielsen, J*; de Groot, M J*; Pusterla, L* (2001) Development and evaluation of a tunable diode laser absorption spectrometer for trace humidity measurements. In: TEMPMEKO 01, June 2001, Berlin, Germany.

Barwood, G P; Gao, K; Gill, P; Huang, G; Klein, H A (2001) Development of an ultra-narrow diode laser for interrogating the 674 nm 2S1/2 - 2D5/2 'clock' transition in Sr+. Proc. SPIE - Int. Soc. Opt. Eng., 4269. pp. 134-142.

Barwood, G P; Gao, K*; Gill, P; Huang, G; Klein, H A (2001) Development of optical frequency standards based upon the 2S1/2-2D5/2 transition in 88Sr+ and 87Sr+. IEEE Trans. Instrum. Meas., 50 (2). pp. 543-547.

Bell, S A; Stevens, M; Barwood, G P; Edwards, C S; Gill, P (2001) Evaluation of a tuneable diode laser absorption spectrometer against the NPL low frost-point generator. In: TEMPMEKO 01, June 2001, Berlin, Germany.

Taylor, P; Webster, S A; Roberts, M; Rowley, W R C; Barwood, G P; Gill, P (2001) Progress towards a single ytterbium ion optical clock. Proc. SPIE - Int. Soc. Opt. Eng., 4269. pp. 155-169.

Edwards, C S; Barwood, G P; Bell, S A; Gill, P; Stevens, M (2001) A tunable diode laser absorption spectrometer for moisture measurements in the low ppbv range. Meas. Sci. Technol., 12. pp. 1214-8.

Barwood, G P; Gao, K; Gill, P; Huang, G; Klein, H A (2000) Development of optical frequency standards based upon the 2S1/2 - 2D5/2 transition in 88Sr+. In: Conference on Precision Electromagnetic Measurements (CPEM) 2000, 14-19 May 2000, Sydney, Australia.

Schirmer, B*; Venzke, H*; Melling, A*; Edwards, C S; Barwood, G P; Gill, P; Stevens, M; Benyon, R*; Mackrodt, P* (2000) High precision trace humidity measurements with a fibre-coupled diode laser absorption spectrometer at atmospheric pressure. Meas. Sci. Technol., 11. pp. 382-391.

Edwards, C S; Barwood, G P; Gill, P; Stevens, M; Schirmer, B*; Benyon, R*; Mackrodt, P* (2000) An IR tunable diode laser absorption spectrometer for trace humidity measurements at atmospheric pressure. IEEE Lasers and Electro-Optics Society Newsletter, 14 (5). pp. 13-14.

Cornish, S L*; Lui, Yi-Wei*; Lane, I C*; Baird, P E G*; Barwood, G P; Taylor, P; Rowley, W R C (2000) Interferometric measurements of 127I2 reference frequencies for 1S-2S spectroscopy in muonium, hydrogen and deuterium. J. Opt. Soc. Am. B, 17 (1). pp. 6-10.

Roberts, M; Taylor, P; Barwood, G P; Rowley, W R C; Gill, P (2000) Observation of the 2S1/2-2F7/2 electric octupole transition in a single 171Yb+ ion. Phys. Rev. A, At. Mol. Opt. Phys., 62 (2). 020501(R)

Klein, H A; Barwood, G P; Gill, P; Huang, G (2000) Single trapped ions for optical frequency standards. Phys. Scr. Vol. T, 86. pp. 33-37.

Edwards, C S; Barwood, G P; Gill, P; Rowley, W R C (1999) A 633nm iodine-stabilised diode laser frequency standard. Metrologia, 36 (1). pp. 41-45.

Edwards, C S; Barwood, G P; Gill, P; Schirmer, B*; Venzke, H*; Melling, A* (1999) Development of an IR tunable diode laser absorption spectrometer for trace humidity measurements at atmospheric pressure. Appl. Opt., 38 (21). pp. 4699-4704.

Barwood, G P; Gill, P; Huang, G; Klein, H A (1999) Development of an optical frequency standard based upon the 2S1/2-2D5/2 transition in Sr+. In: 13th EFTF/ 1999 IEEE FCS Conference Proceedings, 1999.

Macfarlane, G M; Barwood, G P; Rowley, W R C; Gill, P (1999) Interfeometric frequency measurements of an iodine stabilised Nd:YAG laser. IEEE Trans. Instrum. Meas., 48 (2). pp. 600-603.

Taylor, P; Roberts, M; Macfarlane, G M; Barwood, G P; Rowley, W R C; Gill, P (1999) Measurement of the infrared 2F7/2-2D5/2 transition in a single 171Yb+ ion. Phys. Rev. A, At. Mol. Opt. Phys., 60 (4). pp. 2829-2833.

Barwood, G P; Huang, G; Klein, H A; Gill, P; Clarke, R B M* (1999) Sub-kHz comparison of the single-ion optical-clock 2S1/2 - 2D5/2 transition in two 88Sr+ traps. Phys. Rev. A, At. Mol. Opt. Phys., 59. R3178-81

Taylor, P; Roberts, M; Barwood, G P; Gill, P (1998) Combined optical infrared single ion frequency standard. Opt. Lett., 23 (4). pp. 298-300.

Taylor, P; Roberts, M; Barwood, G P; Gill, P (1998) Combined optical-infrared single ion frequency standard. In: Proc. 1998 CPEM Digest, July 1998, Washington, DC, USA.

Taylor, P; Roberts, M; Barwood, G P; Gill, P (1998) Combined optical-infrared single ion-frequency standard. In: CPEM '98 Conference on Precision Electromagnetic Measurements Conference Digest, 6-10 July 2003, Washington DC, USA.

Barwood, G P; Gill, P; Rowley, W R C (1998) High accuracy length metrology using multiple-stage swept-frequency interferometry with laser diodes. Meas. Sci. Technol., 9 (7). pp. 1036-41.

Macfarlane, G M; Barwood, G P; Rowley, W R C; Gill, P (1998) Interferometric frequency measurements of an iodine stabilised Nd:YAG laser. In: Proc. 1998 CPEM Digest, July 1998, Washington, DC, USA.

Macfarlane, G M; Barwood, G P; Rowley, W R C; Gill, P (1998) Interferometric frequency measurements of an iodine stabilised Nd:YAG laser. In: CPEM '98 Conference on Precision Electromagnetic Measurements Conference Digest, 6-10 July 2003, Washington DC, USA.

Barwood, G P; Gill, P; Klein, H A; Rowley, W R C (1998) Sub-kHz "clock" transition linewidths in a cold trapped 88Sr+ ion in low magnetic fields using 1092-nm polarisation switching. Opt. Commun., 151 (1-3). pp. 50-5.

Clarke, R B W*; Riis, E*; Barwood, G P; Gill, P; Huang, G; Klein, H A (1998) A sideband-injection locked extended cavity diode laser for interrogating cold trapped strontium ions. Opt. Commun., 158 (1-6). pp. 36-40.

Barwood, G P; Gill, P; Klein, H A; Rowley, W R C (1997) Clearly resolved secular sidebands on the 2S1/2-2D5/2 674nm clock transition in a single trapped Sr+ ion and prospects for trapped ion frequency standards. IEEE Trans. Instrum. Meas., 46 (2). pp. 133-136.

Taylor, P; Roberts, M; Gateva-Kostova, S V*; Clarke, R B W*; Barwood, G P; Rowley, W R C; Gill, P (1997) Investigation of the 2S1/2-2D5/2 clock transition in a single ytterbium ion. Phys. Rev. A, 56. p. 2699.

Roberts, M; Taylor, P; Barwood, G P; Gill, P; Klein, H A; Rowley, W R C (1997) Observation of an electric octupole transition in a single Ion. Phys. Rev. Lett., 78 (10). pp. 1876-1879.

Barwood, G P; Gill, P; Huang, G; Klein, H A; Rowley, W R C (1997) Single Sr+ Ion spectroscopy with a sub-kHz linewidth diode probe laser. In: 13th International Conference on Laser Spectroscopy, June 1997, Hangzhou, China.

Edwards, C S; Barwood, G P; Gill, P; Rodriguez-Llorente, F*; Rowley, W R C (1996) Frequency-stabilised diode lasers in the visible region using Doppler-free iodine spectra. Opt. Commun.,, 132. pp. 94-100.

Barwood, G P; Gill, P; Klein, H A; Rowley, W R C (1996) Observation of fluorescence from cold trapped Sr ions in a near-zero magnetic field and 674nm probe laser development. In: Proc. Fifth symposium of Frequency Standards and Metrology, 1996, Singapore.

Edwards, C S; Barwood, G P; Gill, P; Rodriguez-Llorente, F*; Rowley, W R C (1996) Stability measurement of 637nm extended cavity diode lasers stabilised to Doppler-free iodine spectra. In: Proc. Fifth symposium on Frequency Standards and Metrology, 1996, Singapore.

Edwards, C S; Barwood, G P; Gill, P; Rowley, W R C (1995) Absolute frequency stabilisation of a 637nm laser diode using Doppler-free I2 spectra. Electron. Lett., 31 (10). pp. 796-797.

Barwood, G P; Edwards, C S; Gill, P; Huang, G; Klein, H A; Rowley, W R C (1995) Precision interferometric frequency measurement of the 674nm 2S1/2 - 2D5/2 transition in a single cold Sr+ ion. IEEE Trans. Instrum. Meas., 44 (2). pp. 117-119.

Barwood, G P; Gill, P; Huang, G; Klein, H A (1995) Studies of trapped strontium ions in low magnetic fields. Appl. Phys. B, Laser Opt., 61 (4). p. 385.

Barwood, G P; Edwards, C S; Gill, P; Klein, H A; Rowley, W R C (1994) Laser cooling and probing of a trapped strontium ion using all-solid-state lasers. AIP Conf. Proc., 290. pp. 35-37.

Barwood, G P; Edwards, C S; Gill, P; Klein, H A; Rowley, W R C (1993) Development of diode and fibre laser sources for a Sr+ trapped ion optical frequency standard. Proc. SPIE - Int. Soc. Opt. Eng., 1837. pp. 271-7.

Barwood, G P; Gill, P; Rowley, W R C (1993) Laser diodes for length determination using swept-frequency interferometry. Meas. Sci. Technol., 4 (9). pp. 988-994.

Barwood, G P; Edwards, C S; Gill, P; Klein, H A; Rowley, W R C (1993) Observation of the 5s2S1/2-4d2D5/2 transition in a single laser-cooled trapped Sr+ ion using an all-solid-state system of lasers. Opt. Lett., 18 (9). pp. 732-734.

Barwood, G P; Gill, P; Rowley, W R C (1993) Optically narrowed Rb-stabilised GaAlAs diode laser frequency standards with 1.5x10-10 absolute accuracy. Proc. SPIE - Int. Soc. Opt. Eng., 1837. pp. 262-270.